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opm-simulators/opm/simulators/wells/GasLiftSingleWellGeneric.cpp
Håkon Hægland 438a712e54 Gas lift optimization for two-phase oil-water. 
Add gas lift optimization support for two-phase oil-water flow.
2022-03-07 15:19:43 +01:00

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/*
Copyright 2020 Equinor ASA.
This file is part of the Open Porous Media project (OPM).
OPM is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
OPM is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with OPM. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <opm/simulators/wells/GasLiftSingleWellGeneric.hpp>
#include <opm/input/eclipse/Schedule/GasLiftOpt.hpp>
#include <opm/input/eclipse/Schedule/Schedule.hpp>
#include <opm/simulators/utils/DeferredLogger.hpp>
#include <opm/simulators/wells/GasLiftWellState.hpp>
#include <opm/simulators/wells/WellState.hpp>
#include <opm/simulators/wells/GroupState.hpp>
#include <fmt/format.h>
#include <cassert>
#include <sstream>
namespace Opm
{
GasLiftSingleWellGeneric::GasLiftSingleWellGeneric(
DeferredLogger& deferred_logger,
WellState& well_state,
const GroupState& group_state,
const Well& ecl_well,
const SummaryState& summary_state,
GasLiftGroupInfo& group_info,
const PhaseUsage& phase_usage,
const Schedule& schedule,
const int report_step_idx,
GLiftSyncGroups& sync_groups,
bool glift_debug
) :
GasLiftCommon(well_state, deferred_logger, glift_debug)
, group_state_{group_state}
, ecl_well_{ecl_well}
, summary_state_{summary_state}
, group_info_{group_info}
, phase_usage_{phase_usage}
, sync_groups_{sync_groups}
, controls_{ecl_well_.productionControls(summary_state_)}
, debug_limit_increase_decrease_{false}
{
this->well_name_ = ecl_well_.name();
const GasLiftOpt& glo = schedule.glo(report_step_idx);
// NOTE: According to LIFTOPT, item 1:
// "Increment size for lift gas injection rate. Lift gas is
// allocated to individual wells in whole numbers of the increment
// size. If gas lift optimization is no longer required, it can be
// turned off by entering a zero or negative number."
// NOTE: This condition was checked in doGasLiftOptimize() in StandardWell
// so it can be assumed that increment_ > 0
this->increment_ = glo.gaslift_increment();
assert( this->increment_ > 0);
// NOTE: The manual (see LIFTOPT, item 2) does not mention
// any default value or restrictions on the economic gradient.
// TODO: The value of the gradient would most likely be a positive
// number. Should we warn or fail on a negative value?
// A negative value for the economic gradient would mean that
// the oil production is decreasing with increased liftgas
// injection (which seems strange)
this->eco_grad_ = glo.min_eco_gradient();
gl_well_ = &glo.well(this->well_name_);
}
/****************************************
* Public methods in alphabetical order
****************************************/
// NOTE: Used from GasLiftStage2
std::optional<GasLiftSingleWellGeneric::GradInfo>
GasLiftSingleWellGeneric::
calcIncOrDecGradient(double oil_rate, double gas_rate, double alq, bool increase) const
{
auto [new_alq_opt, alq_is_limited] = addOrSubtractAlqIncrement_(alq, increase);
// TODO: What to do if ALQ is limited and new_alq != alq?
if (!new_alq_opt)
return std::nullopt;
double new_alq = *new_alq_opt;
if (auto bhp = computeBhpAtThpLimit_(new_alq)) {
auto [new_bhp, bhp_is_limited] = getBhpWithLimit_(*bhp);
// TODO: What to do if BHP is limited?
auto rates = computeWellRates_(new_bhp, bhp_is_limited);
double new_oil_rate, new_gas_rate, new_water_rate;
bool oil_is_limited, gas_is_limited, water_is_limited;
std::tie(new_oil_rate, oil_is_limited) = getOilRateWithLimit_(rates);
std::tie(new_gas_rate, gas_is_limited) = getGasRateWithLimit_(rates);
std::tie(new_water_rate, water_is_limited) = getWaterRateWithLimit_(rates);
if (!increase && new_oil_rate < 0 ) {
return std::nullopt;
}
auto grad = calcEcoGradient_(
oil_rate, new_oil_rate, gas_rate, new_gas_rate, increase);
return GradInfo(grad, new_oil_rate, oil_is_limited,
new_gas_rate, gas_is_limited, new_water_rate, water_is_limited,
new_alq, alq_is_limited);
}
else {
return std::nullopt;
}
}
std::unique_ptr<GasLiftWellState>
GasLiftSingleWellGeneric::
runOptimize(const int iteration_idx)
{
std::unique_ptr<GasLiftWellState> state;
if (this->optimize_) {
if (this->debug_limit_increase_decrease_) {
state = runOptimize1_();
}
else {
state = runOptimize2_();
}
if (state) {
// NOTE: that state->increase() returns a std::optional<bool>, if
// this is std::nullopt it means that we was not able to change ALQ
// (either increase or decrease)
if (state->increase()) { // ALQ changed..
double alq = state->alq();
if (this->debug)
logSuccess_(alq, iteration_idx);
this->well_state_.setALQ(this->well_name_, alq);
const auto& pu = this->phase_usage_;
std::vector<double> well_pot(pu.num_phases, 0.0);
if(pu.phase_used[BlackoilPhases::PhaseIndex::Liquid])
well_pot[pu.phase_pos[BlackoilPhases::PhaseIndex::Liquid]] = state->oilRate();
if(pu.phase_used[BlackoilPhases::PhaseIndex::Aqua])
well_pot[pu.phase_pos[BlackoilPhases::PhaseIndex::Aqua]] = state->waterRate();
if(pu.phase_used[BlackoilPhases::PhaseIndex::Vapour])
well_pot[pu.phase_pos[BlackoilPhases::PhaseIndex::Vapour]] = state->gasRate();
this->well_state_[this->well_name_].well_potentials = well_pot;
}
}
}
return state;
}
/****************************************
* Protected methods in alphabetical order
****************************************/
std::pair<std::optional<double>, bool>
GasLiftSingleWellGeneric::
addOrSubtractAlqIncrement_(double alq, bool increase) const
{
bool limited = false;
double orig_alq = alq;
if (increase) {
alq += this->increment_;
// NOTE: if max_alq_ was defaulted in WLIFTOPT, item 3, it has
// already been set to the largest value in the VFP table in
// the contructor of GasLiftSingleWell
if (alq > this->max_alq_) {
alq = this->max_alq_;
limited = true;
}
}
else { // we are decreasing ALQ
alq -= this->increment_;
if (this->min_alq_ > 0) {
// According to WLIFTOPT item 5: If a positive value is
// specified (min_alq_), the well is allocated at least that amount
// of lift gas, unless the well is unable to flow with
// that rate of lift gas injection, or unless the well can
// already meet one of its own rate limits before
// receiving its minimum lift gas rate.
if (alq < this->min_alq_) {
alq = this->min_alq_;
limited = true;
}
}
else {
if (alq < 0) {
alq = 0.0;
limited = true;
}
}
}
std::optional<double> alq_opt {alq};
// If we were not able to change ALQ (to within rounding error), we
// return std::nullopt
if (limited && checkALQequal_(orig_alq,alq))
alq_opt = std::nullopt;
return {alq_opt, limited};
}
double
GasLiftSingleWellGeneric::
calcEcoGradient_(double oil_rate, double new_oil_rate, double gas_rate,
double new_gas_rate, bool increase) const
{
auto dqo = new_oil_rate - oil_rate;
auto dqg = new_gas_rate - gas_rate;
// TODO: Should the gas rate term in the denominator be subject to the constraint:
//
// alpha_g_ * dqg >= 0.0
//
// ?
auto gradient = (this->alpha_w_ * dqo) / (this->increment_ + this->alpha_g_*dqg);
// TODO: Should we do any error checks on the calculation of the
// gradient?
if (!increase) gradient = -gradient;
return gradient;
}
bool
GasLiftSingleWellGeneric::
checkALQequal_(double alq1, double alq2) const
{
return std::fabs(alq1-alq2) < (this->increment_*ALQ_EPSILON);
}
bool
GasLiftSingleWellGeneric::
checkGroupTargetsViolated(
const BasicRates& rates, const BasicRates& new_rates) const
{
const auto &pairs =
this->group_info_.getWellGroups(this->well_name_);
for (const auto &[group_name, efficiency] : pairs) {
for (const auto rate_type : {Rate::oil, Rate::gas, Rate::water, Rate::liquid}) {
auto target_opt = this->group_info_.getTarget(rate_type, group_name);
if (target_opt) {
auto delta_rate = new_rates[rate_type] - rates[rate_type];
auto new_group_rate = this->group_info_.getRate(rate_type, group_name)
+ efficiency * delta_rate;
if (new_group_rate > *target_opt) {
if (this->debug) {
const std::string msg = fmt::format(
"Group {} : {} rate {} exceeds target {}. Stopping iteration",
group_name, GasLiftGroupInfo::rateToString(rate_type),
new_group_rate, *target_opt);
displayDebugMessage_(msg);
}
return true;
}
}
}
}
return false;
}
bool
GasLiftSingleWellGeneric::
checkInitialALQmodified_(double alq, double initial_alq) const
{
if (checkALQequal_(alq,initial_alq)) {
return false;
}
else {
const std::string msg = fmt::format("initial ALQ changed from {} "
"to {} before iteration starts..", initial_alq, alq);
displayDebugMessage_(msg);
return true;
}
}
bool
GasLiftSingleWellGeneric::
checkThpControl_() const
{
const int well_index = this->well_state_.index(this->well_name_).value();
const Well::ProducerCMode& control_mode =
this->well_state_.well(well_index).production_cmode;
bool thp_control = control_mode == Well::ProducerCMode::THP;
if (this->debug) {
if (!thp_control) {
displayDebugMessage_("Well is not under THP control, skipping iteration..");
}
}
return thp_control;
}
std::optional<GasLiftSingleWellGeneric::BasicRates>
GasLiftSingleWellGeneric::
computeInitialWellRates_() const
{
std::optional<BasicRates> rates;
if (auto bhp = computeBhpAtThpLimit_(this->orig_alq_); bhp) {
{
const std::string msg = fmt::format(
"computed initial bhp {} given thp limit and given alq {}",
*bhp, this->orig_alq_);
displayDebugMessage_(msg);
}
auto [new_bhp, bhp_is_limited] = getBhpWithLimit_(*bhp);
rates = computeWellRates_(new_bhp, bhp_is_limited);
if (rates) {
const std::string msg = fmt::format(
"computed initial well potentials given bhp, "
"oil: {}, gas: {}, water: {}",
rates->oil, rates->gas, rates->water);
displayDebugMessage_(msg);
}
}
else {
displayDebugMessage_("Aborting optimization.");
}
return rates;
}
std::optional<GasLiftSingleWellGeneric::LimitedRates>
GasLiftSingleWellGeneric::
computeLimitedWellRatesWithALQ_(double alq) const
{
std::optional<LimitedRates> limited_rates;
if (auto rates = computeWellRatesWithALQ_(alq); rates) {
limited_rates = getLimitedRatesFromRates_(*rates);
}
return limited_rates;
}
std::optional<GasLiftSingleWellGeneric::BasicRates>
GasLiftSingleWellGeneric::
computeWellRatesWithALQ_(double alq) const
{
std::optional<BasicRates> rates;
auto bhp_opt = computeBhpAtThpLimit_(alq);
if (bhp_opt) {
auto [bhp, bhp_is_limited] = getBhpWithLimit_(*bhp_opt);
rates = computeWellRates_(bhp, bhp_is_limited);
}
return rates;
}
void
GasLiftSingleWellGeneric::
debugCheckNegativeGradient_(double grad, double alq, double new_alq,
double oil_rate, double new_oil_rate,
double gas_rate, double new_gas_rate, bool increase) const
{
{
const std::string msg = fmt::format("calculating gradient: "
"new_oil_rate = {}, oil_rate = {}, grad = {}", new_oil_rate, oil_rate, grad);
displayDebugMessage_(msg);
}
if (grad < 0 ) {
const std::string msg = fmt::format("negative {} gradient detected ({}) : "
"alq: {}, new_alq: {}, "
"oil_rate: {}, new_oil_rate: {}, gas_rate: {}, new_gas_rate: {}",
(increase ? "incremental" : "decremental"),
grad, alq, new_alq, oil_rate, new_oil_rate, gas_rate, new_gas_rate);
displayDebugMessage_(msg);
}
}
void
GasLiftSingleWellGeneric::
debugShowAlqIncreaseDecreaseCounts_()
{
auto inc_count = this->well_state_.gliftGetAlqIncreaseCount(this->well_name_);
auto dec_count = this->well_state_.gliftGetAlqDecreaseCount(this->well_name_);
const std::string msg =
fmt::format("ALQ increase/decrease count : {}/{}", inc_count, dec_count);
displayDebugMessage_(msg);
}
void
GasLiftSingleWellGeneric::
debugShowBhpAlqTable_()
{
double alq = 0.0;
const std::string fmt_fmt1 {"{:^12s} {:^12s} {:^12s} {:^12s}"};
const std::string fmt_fmt2 {"{:>12.5g} {:>12.5g} {:>12.5g} {:>12.5g}"};
const std::string header = fmt::format(fmt_fmt1, "ALQ", "BHP", "oil", "gas");
displayDebugMessage_(header);
auto max_it = 50;
auto it = 1;
while (alq <= (this->max_alq_+this->increment_)) {
auto bhp_at_thp_limit = computeBhpAtThpLimit_(alq);
if (!bhp_at_thp_limit) {
const std::string msg = fmt::format("Failed to get converged potentials "
"for ALQ = {}. Skipping.", alq );
displayDebugMessage_(msg);
}
else {
auto [bhp, bhp_is_limited] = getBhpWithLimit_(*bhp_at_thp_limit);
auto rates = computeWellRates_(bhp, bhp_is_limited, /*debug_out=*/false);
const std::string msg = fmt::format(
fmt_fmt2, alq, bhp, rates.oil, rates.gas);
displayDebugMessage_(msg);
}
alq += this->increment_;
if (it > max_it) {
const std::string msg = fmt::format(
"ALQ table : max iterations {} reached. Stopping iteration.", max_it);
displayDebugMessage_(msg);
break;
}
it++;
}
}
void
GasLiftSingleWellGeneric::
debugShowLimitingTargets_(const LimitedRates& rates) const
{
if (rates.limited()) {
if (rates.oil_is_limited) {
const std::string msg = fmt::format(
"oil rate {} is limited by {} target",
rates.oil,
GasLiftGroupInfo::rateToString(*(rates.oil_limiting_target)));
displayDebugMessage_(msg);
}
if (rates.gas_is_limited) {
const std::string msg = fmt::format(
"gas rate {} is limited by GRAT target",
rates.gas);
displayDebugMessage_(msg);
}
if (rates.water_is_limited) {
const std::string msg = fmt::format(
"water rate {} is limited by {} target",
rates.water,
GasLiftGroupInfo::rateToString(*(rates.water_limiting_target)));
displayDebugMessage_(msg);
}
}
else {
displayDebugMessage_("no rates are currently limited by a target");
}
}
void
GasLiftSingleWellGeneric::
debugShowProducerControlMode() const
{
const int well_index = this->well_state_.index(this->well_name_).value();
const Well::ProducerCMode& control_mode =
this->well_state_.well(well_index).production_cmode;
const std::string msg = fmt::format("Current control mode is: {}",
Well::ProducerCMode2String(control_mode));
displayDebugMessage_(msg);
}
void
GasLiftSingleWellGeneric::
debugShowStartIteration_(double alq, bool increase, double oil_rate)
{
const std::string msg =
fmt::format("starting {} iteration, ALQ = {}, oilrate = {}",
(increase ? "increase" : "decrease"),
alq, oil_rate);
displayDebugMessage_(msg);
}
void
GasLiftSingleWellGeneric::
debugShowTargets_()
{
if (this->controls_.hasControl(Well::ProducerCMode::ORAT)) {
auto target = this->controls_.oil_rate;
const std::string msg = fmt::format("has ORAT control with target {}", target);
displayDebugMessage_(msg);
}
if (this->controls_.hasControl(Well::ProducerCMode::GRAT)) {
auto target = this->controls_.gas_rate;
const std::string msg = fmt::format("has GRAT control with target {}", target);
displayDebugMessage_(msg);
}
if (this->controls_.hasControl(Well::ProducerCMode::LRAT)) {
auto target = this->controls_.liquid_rate;
const std::string msg = fmt::format("has LRAT control with target {}", target);
displayDebugMessage_(msg);
}
}
void
GasLiftSingleWellGeneric::
displayDebugMessage_(const std::string& msg) const
{
if (this->debug) {
const std::string message = fmt::format(
" GLIFT (DEBUG) : Well {} : {}", this->well_name_, msg);
this->deferred_logger_.info(message);
}
}
void
GasLiftSingleWellGeneric::
displayWarning_(const std::string& msg)
{
const std::string message = fmt::format(
"GAS LIFT OPTIMIZATION, WELL {} : {}", this->well_name_, msg);
this->deferred_logger_.warning("WARNING", message);
}
std::pair<double, bool>
GasLiftSingleWellGeneric::
getBhpWithLimit_(double bhp) const
{
bool limited = false;
if (this->controls_.hasControl(Well::ProducerCMode::BHP)) {
auto limit = this->controls_.bhp_limit;
if (bhp < limit) {
bhp = limit;
limited = true;
}
}
return {bhp, limited};
}
// TODO: what if the gas_rate_target_ has been defaulted
// (i.e. value == 0, meaning: "No limit") but the
// oil_rate_target_ has not been defaulted ?
// If the new_oil_rate exceeds the oil_rate_target_ it is cut back,
// but the same cut-back will not happen for the new_gas_rate
// Seems like an inconsistency, since alq should in this
// case also be adjusted (to the smaller value that would
// give oil target rate) but then the gas rate would also be smaller?
// The effect of not reducing the gas rate (if it should be
// reduced?) is that a too large value is used in the
// computation of the economic gradient making the gradient
// smaller than it should be since the term appears in the denominator.
std::pair<double, bool>
GasLiftSingleWellGeneric::
getGasRateWithLimit_(const BasicRates& rates) const
{
auto [rate, target_type] = getRateWithLimit_(Rate::gas, rates);
bool limited = target_type.has_value();
return {rate, limited};
}
// NOTE: If the computed oil rate is larger than the target
// rate of the well, we reduce it to the target rate. This
// will make the economic gradient smaller than it would be
// if we did not reduce the rate, and it is less
// likely that the current gas lift increment will be
// accepted.
// TODO: If it still is accepted, we should ideally reduce the alq
// also since we also reduced the rate. This might involve
// some sort of iteration though..
std::pair<double, bool>
GasLiftSingleWellGeneric::
getOilRateWithLimit_(const BasicRates& rates) const
{
auto [rate, target_type] = getRateWithLimit_(Rate::oil, rates);
bool limited = target_type.has_value();
return {rate, limited};
}
std::pair<double, std::optional<GasLiftSingleWellGeneric::Rate>>
GasLiftSingleWellGeneric::
getOilRateWithLimit2_(const BasicRates& rates) const
{
return getRateWithLimit_(Rate::oil, rates);
}
std::pair<double, bool>
GasLiftSingleWellGeneric::
getWaterRateWithLimit_(const BasicRates& rates) const
{
auto [rate, target_type] = getRateWithLimit_(Rate::water, rates);
bool limited = target_type.has_value();
return {rate, limited};
}
std::pair<double, std::optional<GasLiftSingleWellGeneric::Rate>>
GasLiftSingleWellGeneric::
getWaterRateWithLimit2_(const BasicRates& rates) const
{
return getRateWithLimit_(Rate::water, rates);
}
double
GasLiftSingleWellGeneric::
getRate_(Rate rate, const BasicRates& rates) const
{
switch (rate) {
case Rate::oil:
return rates.oil;
case Rate::gas:
return rates.gas;
case Rate::water:
return rates.water;
case Rate::liquid:
return rates.oil + rates.water;
default:
// Need this to avoid compiler warning : control reaches end of non-void function
throw std::runtime_error("This should not happen");
}
}
double
GasLiftSingleWellGeneric::
getProductionTarget_(Rate rate) const
{
switch (rate) {
case Rate::oil:
return this->controls_.oil_rate;
case Rate::gas:
return this->controls_.gas_rate;
case Rate::water:
return this->controls_.water_rate;
case Rate::liquid:
return this->controls_.liquid_rate;
default:
// Need this to avoid compiler warning : control reaches end of non-void function
throw std::runtime_error("This should not happen");
}
}
std::pair<double, std::optional<GasLiftSingleWellGeneric::Rate>>
GasLiftSingleWellGeneric::
getRateWithLimit_(Rate rate_type, const BasicRates &rates) const
{
double new_rate = getRate_(rate_type, rates);
// If "target_type" is empty at the end of this method, it means the rate
// was not limited. Otherwise, target_type gives the reason (the type of target)
// for why the rate was limited.
std::optional<Rate> target_type;
if (hasProductionControl_(rate_type)) {
auto target = getProductionTarget_(rate_type);
if (new_rate > target) {
const std::string msg = fmt::format("limiting {} rate to target: "
"computed rate: {}, target: {}",
GasLiftGroupInfo::rateToString(rate_type), new_rate, target);
displayDebugMessage_(msg);
new_rate = target;
target_type = rate_type;
}
}
if (((rate_type == Rate::oil) || (rate_type == Rate::water))
&& hasProductionControl_(Rate::liquid))
{
double rate2;
if (rate_type == Rate::oil) {
rate2 = getRate_(Rate::water, rates);
}
else {
rate2 = getRate_(Rate::oil, rates);
}
// Note: Since "new_rate" was first updated for ORAT or WRAT, see first "if"
// statement in the method, the rate is limited due to LRAT only if
// it becomes less than the rate limited by a WRAT or ORAT target..
double liq_rate = new_rate + rate2;
auto liq_target = getProductionTarget_(Rate::liquid);
if (liq_rate > liq_target) {
double fraction = new_rate / liq_rate;
// NOTE: since
// fraction * liq_rate = new_rate,
// we must have
// fraction * liq_target < new_rate
// since
// liq_target < liq_rate
// therefore new_rate will become less than it original was and
// limited = true.
new_rate = fraction * liq_target;
target_type = Rate::liquid;
const std::string msg = fmt::format(
"limiting {} rate to {} due to LRAT target: "
"computed LRAT: {}, target LRAT: {}",
GasLiftGroupInfo::rateToString(rate_type), new_rate,
liq_rate, liq_target);
displayDebugMessage_(msg);
}
}
// TODO: Also check RESV target?
return { new_rate, target_type};
}
std::pair<double, bool>
GasLiftSingleWellGeneric::
getOilRateWithGroupLimit_(double new_oil_rate, double oil_rate) const
{
[[maybe_unused]] auto [rate, gr_name, efficiency]
= getRateWithGroupLimit_(Rate::oil, new_oil_rate, oil_rate);
bool limited = gr_name != nullptr;
return {rate, limited};
}
std::pair<double, bool>
GasLiftSingleWellGeneric::
getGasRateWithGroupLimit_(double new_gas_rate, double gas_rate) const
{
[[maybe_unused]] auto [rate, gr_name, efficiency]
= getRateWithGroupLimit_(Rate::gas, new_gas_rate, gas_rate);
bool limited = gr_name != nullptr;
return {rate, limited};
}
std::pair<double, bool>
GasLiftSingleWellGeneric::
getWaterRateWithGroupLimit_(double new_water_rate, double water_rate) const
{
[[maybe_unused]] auto [rate, gr_name, efficiency] = getRateWithGroupLimit_(
Rate::water, new_water_rate, water_rate);
bool limited = gr_name != nullptr;
return {rate, limited};
}
std::tuple<double, double, bool, bool>
GasLiftSingleWellGeneric::
getLiquidRateWithGroupLimit_(const double new_oil_rate, const double oil_rate,
const double new_water_rate, const double water_rate) const
{
auto liquid_rate = oil_rate + water_rate;
auto new_liquid_rate = new_oil_rate + new_water_rate;
auto [liquid_rate_limited, group_name, efficiency]
= getRateWithGroupLimit_(Rate::liquid, new_liquid_rate, liquid_rate);
bool limited = group_name != nullptr;
if (limited) {
// the oil, gas, and water cases can be handled directly by
// getRateWithGroupLimit_() above. However, for the liquid case
// we must do some postprocessing. I chose to include it here
// instead of cluttering up getRateWithGroupLimit_() with this
// special case.
double delta_water = new_water_rate - water_rate;
double delta_oil = new_oil_rate - oil_rate;
double gr_water_rate = this->group_info_.waterRate(*group_name);
double gr_oil_rate = this->group_info_.oilRate(*group_name);
// NOTE: these rates are too large according to the limited liquid rate
// but it does not matter since we are only using them to calculate
// the fraction of the liquid corresponding to the oil phase
double new_gr_water_rate = gr_water_rate + efficiency * delta_water;
double new_gr_oil_rate = gr_oil_rate + efficiency * delta_oil;
double new_gr_liquid_rate = new_gr_water_rate + new_gr_oil_rate;
double oil_fraction = new_gr_oil_rate / new_gr_liquid_rate;
double delta_liquid = liquid_rate_limited - liquid_rate;
auto limited_oil_rate = oil_rate + oil_fraction * delta_liquid;
auto limited_water_rate = water_rate + (1.0 - oil_fraction) * delta_liquid;
return {limited_oil_rate, limited_water_rate, limited, limited};
}
return {new_oil_rate, new_water_rate, limited, limited};
}
std::tuple<double, const std::string*, double>
GasLiftSingleWellGeneric::
getRateWithGroupLimit_(
Rate rate_type, const double new_rate, const double old_rate) const
{
const double delta_rate = new_rate - old_rate;
if (delta_rate > 0) {
// It is required that the production rate for a given group is
// is less than or equal to its target rate, see assert() below.
// Then it only makes sense to check if the group target is exceeded
// if delta_rate > 0
const auto &pairs =
this->group_info_.getWellGroups(this->well_name_);
double limited_rate = new_rate;
double gr_target, new_gr_rate, efficiency;
const std::string *group_name = nullptr;
for (const auto& [group_name_temp, efficiency_temp] : pairs) {
auto gr_target_opt = this->group_info_.getTarget(rate_type, group_name_temp);
if (gr_target_opt) {
double gr_target_temp = *gr_target_opt;
double gr_rate_temp =
this->group_info_.getRate(rate_type, group_name_temp);
if (gr_rate_temp > gr_target_temp) {
if (this->debug) {
debugInfoGroupRatesExceedTarget(
rate_type, group_name_temp, gr_rate_temp, gr_target_temp);
}
group_name = &group_name_temp;
efficiency = efficiency_temp;
limited_rate = old_rate;
gr_target = gr_target_temp;
new_gr_rate = gr_rate_temp;
break;
}
double new_gr_rate_temp = gr_rate_temp + efficiency_temp * delta_rate;
if (new_gr_rate_temp > gr_target_temp) {
double limited_rate_temp =
old_rate + (gr_target_temp - gr_rate_temp) / efficiency_temp;
if (limited_rate_temp < limited_rate) {
group_name = &group_name_temp;
efficiency = efficiency_temp;
limited_rate = limited_rate_temp;
gr_target = gr_target_temp;
new_gr_rate = new_gr_rate_temp;
}
}
}
}
if (group_name) {
if (this->debug) {
const std::string msg = fmt::format(
"limiting {} rate from {} to {} to meet group target {} "
"for group {}. Computed group rate was: {}",
GasLiftGroupInfo::rateToString(rate_type),
new_rate, limited_rate, gr_target,
*group_name, new_gr_rate);
displayDebugMessage_(msg);
}
return { limited_rate, group_name, efficiency };
}
}
return { new_rate, /*group_name =*/nullptr, /*efficiency dummy value*/0.0 };
}
std::optional<GasLiftSingleWellGeneric::LimitedRates>
GasLiftSingleWellGeneric::
getInitialRatesWithLimit_() const
{
std::optional<LimitedRates> limited_rates;
if (auto rates = computeInitialWellRates_(); rates) {
if (this->debug) {
displayDebugMessage_(
"Maybe limiting initial rates before optimize loop..");
}
auto temp_rates = getLimitedRatesFromRates_(*rates);
BasicRates old_rates = getWellStateRates_();
limited_rates = updateRatesToGroupLimits_(old_rates, temp_rates);
}
return limited_rates;
}
GasLiftSingleWellGeneric::LimitedRates
GasLiftSingleWellGeneric::
getLimitedRatesFromRates_(const BasicRates& rates) const
{
auto [oil_rate, oil_limiting_target] = getOilRateWithLimit2_(rates);
auto [gas_rate, gas_is_limited] = getGasRateWithLimit_(rates);
auto [water_rate, water_limiting_target] = getWaterRateWithLimit2_(rates);
bool oil_is_limited = oil_limiting_target.has_value();
bool water_is_limited = water_limiting_target.has_value();
return LimitedRates{
oil_rate, gas_rate, water_rate,
oil_is_limited, gas_is_limited, water_is_limited, rates.bhp_is_limited,
oil_limiting_target, water_limiting_target};
}
GasLiftSingleWellGeneric::BasicRates
GasLiftSingleWellGeneric::
getWellStateRates_() const
{
const int well_index = this->well_state_.index(this->well_name_).value();
const auto& pu = this->phase_usage_;
const auto& ws= this->well_state_.well(well_index);
const auto& wrate = ws.well_potentials;
const auto oil_rate = pu.phase_used[Oil]
? wrate[pu.phase_pos[Oil]]
: 0.0;
const auto gas_rate = pu.phase_used[Gas]
? wrate[pu.phase_pos[Gas]]
: 0.0;
const auto water_rate = pu.phase_used[Water]
? wrate[pu.phase_pos[Water]]
: 0.0;
if (this->debug) {
const std::string msg = fmt::format("Initial surface rates: oil : {}, "
"gas : {}, water : {}", oil_rate, gas_rate, water_rate);
displayDebugMessage_(msg);
}
return BasicRates{oil_rate, water_rate, gas_rate, /*bhp_is_limited=*/false};
}
bool
GasLiftSingleWellGeneric::
hasProductionControl_(Rate rate) const
{
switch (rate) {
case Rate::oil:
return this->controls_.hasControl(Well::ProducerCMode::ORAT);
case Rate::gas:
return this->controls_.hasControl(Well::ProducerCMode::GRAT);
case Rate::water:
return this->controls_.hasControl(Well::ProducerCMode::WRAT);
case Rate::liquid:
return this->controls_.hasControl(Well::ProducerCMode::LRAT);
default:
// Need this to avoid compiler warning : control reaches end of non-void function
throw std::runtime_error("This should not happen");
}
}
std::pair<GasLiftSingleWellGeneric::LimitedRates, double>
GasLiftSingleWellGeneric::
increaseALQtoPositiveOilRate_(double alq, const LimitedRates& orig_rates) const
{
bool stop_iteration = false;
double temp_alq = alq;
// use the copy constructor to only copy the rates
BasicRates rates = orig_rates;
while(!stop_iteration) {
temp_alq += this->increment_;
if (temp_alq > this->max_alq_) break;
auto temp_rates = computeWellRatesWithALQ_(temp_alq);
if (!temp_rates) break;
alq = temp_alq;
rates = *temp_rates;
if (rates.oil > 0) break;
}
// TODO: what about group limits?
return {getLimitedRatesFromRates_(rates), alq};
}
std::pair<GasLiftSingleWellGeneric::LimitedRates, double>
GasLiftSingleWellGeneric::
increaseALQtoMinALQ_(const double orig_alq, const LimitedRates& orig_rates) const
{
auto min_alq = this->min_alq_;
assert(min_alq >= 0);
assert(orig_alq < min_alq);
assert(min_alq < this->max_alq_);
bool stop_iteration = false;
double alq = orig_alq;
LimitedRates rates = orig_rates;
while(!stop_iteration) {
double temp_alq = alq + this->increment_;
if (temp_alq >= min_alq) break;
auto temp_rates = computeLimitedWellRatesWithALQ_(temp_alq);
if (!temp_rates) break;
alq = temp_alq;
rates = *temp_rates;
if (rates.limited()) break;
}
return std::make_pair(rates, alq);
}
void
GasLiftSingleWellGeneric::
logSuccess_(double alq, const int iteration_idx)
{
const std::string message = fmt::format(
"GLIFT, IT={}, WELL {} : {} ALQ from {} to {}",
iteration_idx,
this->well_name_,
((alq > this->orig_alq_) ? "increased" : "decreased"),
this->orig_alq_, alq);
this->deferred_logger_.info(message);
}
std::pair<GasLiftSingleWellGeneric::LimitedRates, double>
GasLiftSingleWellGeneric::
maybeAdjustALQbeforeOptimizeLoop_(
const LimitedRates& orig_rates, const double orig_alq, const bool increase) const
{
double alq = orig_alq;
LimitedRates rates = orig_rates;
if (this->debug) {
const std::string msg = fmt::format("initial ALQ: {}", alq);
displayDebugMessage_(msg);
}
if (!increase) {
// NOTE: Try to decrease ALQ down to a value where the groups
// maximum alq target and the total gas + alq target is not violated
std::tie(rates, alq) = reduceALQtoGroupAlqLimits_(alq, orig_rates);
if(orig_rates.limited()) {
// NOTE: Try to decrease ALQ down to a value where the well target is
// not exceeded.
// NOTE: This may reduce ALQ below the minimum value set in WLIFTOPT
// item 5. However, this is OK since the rate target is met and there
// is no point in using a higher ALQ value then.
auto [rates1, alq1] = reduceALQtoWellTarget_(alq, orig_rates);
auto [rates2, alq2] = reduceALQtoGroupTarget(alq, orig_rates);
if (alq1 < alq2) {
alq = alq1;
rates = rates1;
}
else {
alq = alq2;
rates = rates2;
}
}
} else {
if (orig_rates.oil < 0) {
// Try to increase ALQ up to a value where oil_rate is positive
std::tie(rates, alq) = increaseALQtoPositiveOilRate_(alq, rates);
}
if ((this->min_alq_> 0) && (alq < this->min_alq_)) {
// Try to increase ALQ up to the minimum limit without checking
// the economic gradient..
std::tie(rates, alq) = increaseALQtoMinALQ_(alq, rates);
}
}
if (orig_alq != alq) {
if (this->debug) {
const std::string msg = fmt::format("adjusted ALQ to: {}", alq);
displayDebugMessage_(msg);
}
double delta_alq = alq - orig_alq;
updateGroupRates_(orig_rates, rates, delta_alq);
}
return {rates, alq};
}
bool has_control(int controls, Group::InjectionCMode cmode) {
return ((controls & static_cast<int>(cmode)) != 0);
}
// Reduce ALQ to the lowest value greater than zero that still makes at
// least one rate limited w.r.t. group targets, or reduce ALQ to zero if
// such positive ALQ value cannot be found.
std::pair<GasLiftSingleWellGeneric::LimitedRates, double>
GasLiftSingleWellGeneric::
reduceALQtoGroupAlqLimits_(const double orig_alq, const LimitedRates& orig_rates) const
{
bool stop_this_iteration = false;
double alq = orig_alq;
BasicRates rates{ orig_rates };
double temp_alq = orig_alq;
while(!stop_this_iteration) {
if (temp_alq == 0) break;
temp_alq -= this->increment_;
if (temp_alq < 0) temp_alq = 0;
auto new_rates = computeWellRatesWithALQ_(temp_alq);
if (!new_rates) break;
auto delta_alq = temp_alq - orig_alq;
auto delta_gas_rate = new_rates->gas - orig_rates.gas;
if (!checkGroupTotalRateExceeded(delta_alq, delta_gas_rate)) {
break;
}
rates = *new_rates;
alq = temp_alq;
}
if (alq == orig_alq) {
return {orig_rates, orig_alq};
}
else {
LimitedRates limited_rates = getLimitedRatesFromRates_(rates);
return {limited_rates, alq};
}
}
// Reduce ALQ to the lowest value greater than zero that still makes at
// least one rate limited w.r.t. group targets, or reduce ALQ to zero if
// such positive ALQ value cannot be found.
std::pair<GasLiftSingleWellGeneric::LimitedRates, double>
GasLiftSingleWellGeneric::
reduceALQtoGroupTarget(const double orig_alq, const LimitedRates& orig_rates) const
{
bool stop_this_iteration = true;
const std::vector<std::pair<std::string,double>>& pairs =
this->group_info_.getWellGroups(this->well_name_);
for (const auto &pair /*<group_name, efficiency>*/ : pairs) {
const auto& group_name = pair.first;
if (!this->group_state_.has_production_control(group_name))
continue;
if (this->group_info_.hasAnyTarget(group_name)) {
stop_this_iteration = false;
displayDebugMessage_(
"Reducing ALQ to meet group target(s) before iteration starts.");
break;
}
}
double alq = orig_alq;
BasicRates rates{ orig_rates };
double temp_alq = orig_alq;
while(!stop_this_iteration) {
if (temp_alq == 0) break;
temp_alq -= this->increment_;
if (temp_alq < 0) temp_alq = 0;
auto new_rates = computeWellRatesWithALQ_(temp_alq);
if (!new_rates) break;
if (!checkGroupTargetsViolated(rates, *new_rates)) {
break;
}
rates = *new_rates;
alq = temp_alq;
}
if (alq == orig_alq) {
return {orig_rates, orig_alq};
}
else {
LimitedRates limited_rates = getLimitedRatesFromRates_(rates);
return {limited_rates, alq};
}
}
// Reduce ALQ to the lowest value greater than zero that still makes at
// least one rate limited w.r.t. well targets, or reduce ALQ to zero if
// such positive ALQ value cannot be found.
std::pair<GasLiftSingleWellGeneric::LimitedRates, double>
GasLiftSingleWellGeneric::
reduceALQtoWellTarget_(const double orig_alq, const LimitedRates& rates) const
{
// this method should only be called if "rates" is limited
assert(rates.limited());
if (this->debug) {
displayDebugMessage_(
"Reducing ALQ to meet well targets before iteration starts..");
debugShowLimitingTargets_(rates);
}
double alq = orig_alq;
double temp_alq = alq;
std::optional<LimitedRates> new_rates;
bool stop_iteration = false;
while(!stop_iteration) {
if (temp_alq == 0) break;
temp_alq -= this->increment_;
if (temp_alq < 0) temp_alq = 0;
auto temp_rates = computeLimitedWellRatesWithALQ_(temp_alq);
if (!temp_rates) break; // failed to compute BHP given THP limit and ALQ
// keep iterating until no rate is limited
if (!temp_rates->limited()) break;
alq = temp_alq;
new_rates = temp_rates;
}
assert( alq <= orig_alq );
if (this->debug) {
if (alq < orig_alq) {
// NOTE: ALQ may drop below zero before we are able to meet the target
const std::string msg = fmt::format(
"Reduced ALQ from {} to {} to meet rate targets. Rates (new, old) : "
"oil(({}, {}), gas({}, {}), water({}, {})",
orig_alq, alq,
new_rates->oil, rates.oil,
new_rates->gas, rates.gas,
new_rates->water, rates.water);
displayDebugMessage_(msg);
}
else if (alq == orig_alq) {
// We might not be able to reduce ALQ, for example if ALQ starts out at zero.
const std::string msg = fmt::format(
"Not able to reduce ALQ {} further. ", orig_alq);
displayDebugMessage_(msg);
}
}
if (new_rates) {
return {*new_rates, alq};
}
else {
return {rates, orig_alq};
}
}
// INPUT:
// - increase (boolean) :
// - true : try increase the lift gas supply,
// - false : try decrease lift gas supply.
//
// OUTPUT:
//
// - return value: a new GasLiftWellState or nullptr
//
std::unique_ptr<GasLiftWellState>
GasLiftSingleWellGeneric::
runOptimizeLoop_(bool increase)
{
if (this->debug) debugShowProducerControlMode();
std::unique_ptr<GasLiftWellState> ret_value; // nullptr initially
auto rates = getInitialRatesWithLimit_();
if (!rates) return ret_value;
// if (this->debug) debugShowBhpAlqTable_();
if (this->debug) debugShowAlqIncreaseDecreaseCounts_();
if (this->debug) debugShowTargets_();
bool success = false; // did we succeed to increase alq?
bool alq_is_limited = false;
auto cur_alq = this->orig_alq_;
LimitedRates new_rates = *rates;
auto [temp_rates2, new_alq] = maybeAdjustALQbeforeOptimizeLoop_(
*rates, cur_alq, increase);
if (checkInitialALQmodified_(new_alq, cur_alq)) {
auto delta_alq = new_alq - cur_alq;
new_rates = temp_rates2;
cur_alq = new_alq;
success = true;
updateGroupRates_(*rates, new_rates, delta_alq);
}
OptimizeState state {*this, increase};
auto temp_alq = cur_alq;
if (checkThpControl_()) {
if (this->debug) debugShowStartIteration_(temp_alq, increase, new_rates.oil);
}
else {
// If the well is not under THP control, we can still use the previous
// initial adjustment of ALQ by using the well's THP limit to calculate
// BHP and then well rates from that.
// This is useful for example for wells under group control to reduce
// their gaslift. A typical case for this could be that a new well opens up.
// Then gaslift can be reduced while still keeping the group target.
state.stop_iteration = true;
}
while (!state.stop_iteration && (++state.it <= this->max_iterations_)) {
if (state.checkRatesViolated(new_rates)) break;
if (state.checkAlqOutsideLimits(temp_alq, new_rates.oil)) break;
std::optional<double> alq_opt;
std::tie(alq_opt, alq_is_limited) = state.addOrSubtractAlqIncrement(temp_alq);
if (!alq_opt) break;
auto delta_alq = *alq_opt - temp_alq;
if (checkGroupALQrateExceeded(delta_alq)) break;
temp_alq = *alq_opt;
if (this->debug) state.debugShowIterationInfo(temp_alq);
rates = new_rates;
auto temp_rates = computeLimitedWellRatesWithALQ_(temp_alq);
if (!temp_rates) break;
if (temp_rates->bhp_is_limited)
state.stop_iteration = true;
temp_rates = updateRatesToGroupLimits_(*rates, *temp_rates);
auto delta_gas_rate = temp_rates->gas - rates->gas;
if (checkGroupTotalRateExceeded(delta_alq, delta_gas_rate)) break;
/* if (this->debug_abort_if_increase_and_gas_is_limited_) {
if (gas_is_limited && increase) {
// if gas is limited we do not want to increase
displayDebugMessage_(
"increasing ALQ and gas is limited -> aborting iteration");
break;
}
}
*/
auto gradient = state.calcEcoGradient(
rates->oil, temp_rates->oil, rates->gas, temp_rates->gas);
if (this->debug)
debugCheckNegativeGradient_(
gradient, cur_alq, temp_alq, rates->oil, temp_rates->oil,
rates->gas, temp_rates->gas, increase);
if (state.checkEcoGradient(gradient)) break;
cur_alq = temp_alq;
success = true;
new_rates = *temp_rates;
updateGroupRates_(*rates, new_rates, delta_alq);
}
if (state.it > this->max_iterations_) {
warnMaxIterationsExceeded_();
}
std::optional<bool> increase_opt;
if (success) {
this->well_state_.gliftUpdateAlqIncreaseCount(this->well_name_, increase);
increase_opt = increase;
}
else {
increase_opt = std::nullopt;
}
ret_value = std::make_unique<GasLiftWellState>(
new_rates.oil, new_rates.oil_is_limited,
new_rates.gas, new_rates.gas_is_limited,
cur_alq, alq_is_limited, new_rates.water, increase_opt);
return ret_value;
}
std::unique_ptr<GasLiftWellState>
GasLiftSingleWellGeneric::
runOptimize1_()
{
std::unique_ptr<GasLiftWellState> state;
int inc_count = this->well_state_.gliftGetAlqIncreaseCount(this->well_name_);
int dec_count = this->well_state_.gliftGetAlqDecreaseCount(this->well_name_);
if (dec_count == 0 && inc_count == 0) {
state = tryIncreaseLiftGas_();
if (!state || !(state->alqChanged())) {
state = tryDecreaseLiftGas_();
}
}
else if (dec_count == 0) {
assert(inc_count > 0);
state = tryIncreaseLiftGas_();
}
else if (inc_count == 0) {
assert(dec_count > 0);
state = tryDecreaseLiftGas_();
}
return state;
}
std::unique_ptr<GasLiftWellState>
GasLiftSingleWellGeneric::
runOptimize2_()
{
std::unique_ptr<GasLiftWellState> state;
state = tryIncreaseLiftGas_();
if (!state || !(state->alqChanged())) {
state = tryDecreaseLiftGas_();
}
return state;
}
std::unique_ptr<GasLiftWellState>
GasLiftSingleWellGeneric::
tryDecreaseLiftGas_()
{
return runOptimizeLoop_(/*increase=*/ false);
}
std::unique_ptr<GasLiftWellState>
GasLiftSingleWellGeneric::
tryIncreaseLiftGas_()
{
return runOptimizeLoop_(/*increase=*/ true);
}
void
GasLiftSingleWellGeneric::
setAlqMinRate_(const GasLiftOpt::Well& well)
{
// NOTE: According to WLIFTOPT item 5 :
// if min_rate() is negative, it means: allocate at least enough lift gas
// to enable the well to flow
// NOTE: "to enable the well to flow" : How to interpret this?
// We choose to interpret it to mean a positive oil rate as returned from
//
// computeWellRates_(bhp, cur_potentials);
//
// So even if the well is producing gas, if the oil rate is zero
// we say that the "well is not flowing".
//
// Note that if WECON item 2 is set, the well can be shut off
// before the flow rate reaches zero. Also,
// if bhp drops below the bhp lower limit, the well might switch to bhp
// control before the oil rate becomes zero.
this->min_alq_ = well.min_rate();
if (this->min_alq_ > 0) {
if (this->min_alq_ >= this->max_alq_) {
// NOTE: We reset the value to a negative value.
// negative value means: Allocate at least enough lift gas
// to allow the well to flow.
// TODO: Consider other options for resetting the value..
this->min_alq_ = -1;
displayWarning_("Minimum ALQ value is larger than maximum ALQ value!"
" Resetting value.");
}
}
}
void
GasLiftSingleWellGeneric::
updateGroupRates_(
const LimitedRates& rates, const LimitedRates& new_rates, double delta_alq) const
{
double delta_oil = new_rates.oil - rates.oil;
double delta_gas = new_rates.gas - rates.gas;
double delta_water = new_rates.water - rates.water;
const auto &pairs =
this->group_info_.getWellGroups(this->well_name_);
for (const auto &[group_name, efficiency] : pairs) {
int idx = this->group_info_.getGroupIdx(group_name);
// This will notify the optimize loop in BlackoilWellModel, see
// gasLiftOptimizationStage1() in BlackoilWellModel_impl.hpp
// that this group_info needs to be synchronized to the other MPI ranks
this->sync_groups_.insert(idx);
this->group_info_.update(group_name,
efficiency * delta_oil,
efficiency * delta_gas,
efficiency * delta_water,
efficiency * delta_alq);
}
}
GasLiftSingleWellGeneric::LimitedRates
GasLiftSingleWellGeneric::
updateRatesToGroupLimits_(
const BasicRates& old_rates, const LimitedRates& rates) const
{
LimitedRates new_rates = rates;
auto [new_oil_rate, oil_is_limited] = getOilRateWithGroupLimit_(
new_rates.oil, old_rates.oil);
if (oil_is_limited) {
new_rates.oil_limiting_target = Rate::oil;
}
auto [new_gas_rate, gas_is_limited] = getGasRateWithGroupLimit_(
new_rates.gas, old_rates.gas);
auto [new_water_rate, water_is_limited] = getWaterRateWithGroupLimit_(
new_rates.water, old_rates.water);
if (water_is_limited) {
new_rates.water_limiting_target = Rate::water;
}
auto [new_oil_rate2, new_water_rate2, oil_is_limited2, water_is_limited2]
= getLiquidRateWithGroupLimit_(
new_oil_rate, old_rates.oil, new_water_rate, old_rates.water);
if (oil_is_limited2) {
new_rates.oil_limiting_target = Rate::liquid;
}
if (water_is_limited2) {
new_rates.water_limiting_target = Rate::liquid;
}
new_rates.oil = new_oil_rate2;
new_rates.gas = new_gas_rate;
new_rates.water = new_water_rate2;
new_rates.oil_is_limited = rates.oil_is_limited || oil_is_limited || oil_is_limited2;
new_rates.gas_is_limited = rates.gas_is_limited || gas_is_limited;
new_rates.water_is_limited =
rates.water_is_limited || water_is_limited || water_is_limited2;
if (oil_is_limited || oil_is_limited2 || gas_is_limited
|| water_is_limited || water_is_limited2) {
new_rates.limit_type = LimitedRates::LimitType::group;
}
return new_rates;
}
// Called when we should use a fixed ALQ value
void
GasLiftSingleWellGeneric::
updateWellStateAlqFixedValue_(const GasLiftOpt::Well& well)
{
auto& max_alq_optional = well.max_rate();
if (max_alq_optional) {
// According to WLIFTOPT, item 3:
// If item 2 is NO, then item 3 is regarded as the fixed
// lift gas injection rate for the well.
auto new_alq = *max_alq_optional;
this->well_state_.setALQ(this->well_name_, new_alq);
}
// else {
// // If item 3 is defaulted, the lift gas rate remains
// // unchanged at its current value.
//}
}
// Determine if we should use a fixed ALQ value.
//
// From the manual for WLIFTOPT, item 2:
// Is the well's lift gas injection rate to be calculated by the
// optimization facility?
// - YES : The well's lift gas injection rate is calculated by the
// optimization facility.
// - NO : The well's lift gas injection rate remains fixed at a
// value that can be set either in Item 3 of this keyword, or in
// Item 12 of keyword WCONPROD, or with keyword WELTARG.
bool
GasLiftSingleWellGeneric::
useFixedAlq_(const GasLiftOpt::Well& well)
{
auto wliftopt_item2 = well.use_glo();
if (wliftopt_item2) {
return false;
}
else {
displayDebugMessage_("WLIFTOPT item2 = NO. Skipping optimization.");
// auto& max_alq_optional = well.max_rate();
// if (max_alq_optional) {
// According to WLIFTOPT, item 3:
// If item 2 is NO, then item 3 is regarded as the fixed
// lift gas injection rate for the well.
// }
// else {
// If item 3 is defaulted, the lift gas rate remains
// unchanged at its current value.
// }
return true;
}
}
void
GasLiftSingleWellGeneric::
debugInfoGroupRatesExceedTarget(
Rate rate_type, const std::string& gr_name, double rate, double target) const
{
const std::string msg = fmt::format("{} rate for group {} exceeds target: "
"rate = {}, target = {}, the old rate is kept.",
GasLiftGroupInfo::rateToString(rate_type),
gr_name, rate, target);
displayDebugMessage_(msg);
}
void
GasLiftSingleWellGeneric::
warnMaxIterationsExceeded_()
{
const std::string msg = fmt::format(
"Max iterations ({}) exceeded", this->max_iterations_);
displayWarning_(msg);
}
/****************************************
* Methods declared in OptimizeState
****************************************/
std::pair<std::optional<double>, bool>
GasLiftSingleWellGeneric::OptimizeState::
addOrSubtractAlqIncrement(double alq)
{
auto [alq_opt, limited]
= this->parent.addOrSubtractAlqIncrement_(alq, this->increase);
if (!alq_opt) {
const std::string msg = fmt::format(
"iteration {}, alq = {} : not able to {} ALQ increment",
this->it, alq, (this->increase ? "add" : "subtract"));
}
return {alq_opt, limited};
}
double
GasLiftSingleWellGeneric::OptimizeState::
calcEcoGradient(double oil_rate, double new_oil_rate,
double gas_rate, double new_gas_rate)
{
return this->parent.calcEcoGradient_(oil_rate, new_oil_rate,
gas_rate, new_gas_rate, this->increase);
}
// NOTE: According to WLIFTOPT item 5 :
// if min_rate() is negative, it means: allocate at least enough lift gas
// to enable the well to flow
// We will interpret this as (see discussion above GasLiftSingleWell()
// in this file): Allocate at least the amount of lift gas needed to
// get a positive oil production rate.
bool
GasLiftSingleWellGeneric::OptimizeState::
checkAlqOutsideLimits(double alq, [[maybe_unused]] double oil_rate)
{
std::ostringstream ss;
bool result = false;
if (this->increase) {
if (alq >= this->parent.max_alq_) {
ss << "ALQ >= " << this->parent.max_alq_ << " (max limit), "
<< "stopping iteration";
result = true;
}
else { // checking the minimum limit...
// NOTE: A negative min_alq_ means: allocate at least enough lift gas
// to enable the well to flow, see WLIFTOPT item 5.
if (this->parent.min_alq_ < 0) {
// - if oil rate is negative (i.e. the well is not flowing), continue to
// increase ALQ (according WLIFTOPT item 5) and try make the well
// flow.
// - else if oil rate is already positive, there is no minimum
// limit for ALQ in this case
result = false;
}
else {
// NOTE: checking for a lower limit is not necessary
// when increasing alq. If ALQ was smaller than the minimum when
// we entered the runOptimizeLoop_() method,
// increaseALQtoMinALQ_() will ensure that ALQ >= min_alq
assert(alq >= this->parent.min_alq_ );
result = false;
}
}
}
else { // we are decreasing lift gas
if ( alq == 0 ) {
ss << "ALQ is zero, cannot decrease further. Stopping iteration.";
result = true;
}
else if ( alq < 0 ) {
ss << "Negative ALQ: " << alq << ". Stopping iteration.";
result = true;
}
// NOTE: A negative min_alq_ means: allocate at least enough lift gas
// to enable the well to flow, see WLIFTOPT item 5.
if (this->parent.min_alq_ < 0) {
// We know that the well is flowing (oil_rate > 0) since that was
// already checked in runOptimizeLoop_() by calling checkNegativeOilRate()
assert(oil_rate >= 0);
result = false;
}
else {
if (alq <= this->parent.min_alq_ ) {
// According to WLIFTOPT item 5:
// "If a positive value is specified, the well is
// allocated at least that amount of lift gas,
// unless the well is unable to flow with that rate
// of lift gas injection, or unless the well can
// already meet one of its own rate limits before
// receiving its minimum lift gas rate."
//
// - We already know that the well is flowing, (oil_rate > 0),
// since that was already checked in runOptimizeLoop_() by calling
// checkRatesViolated().
// - We also know that the rate limit was not exceeded since that was
// checked by checkRatesViolated()
assert( oil_rate >= 0);
ss << "ALQ <= " << this->parent.min_alq_ << " (min limit), "
<< "stopping iteration";
result = true;
}
else {
// NOTE: checking for an upper limit should not be necessary
// when decreasing alq.. so this is just to catch an
// illegal state at an early point.
if (alq >= this->parent.max_alq_) {
warn_( "unexpected: alq above upper limit when trying to "
"decrease lift gas. aborting iteration.");
result = true;
}
else {
result = false;
}
}
}
}
if (this->parent.debug) {
const std::string msg = ss.str();
if (!msg.empty())
this->parent.displayDebugMessage_(msg);
}
return result;
}
bool
GasLiftSingleWellGeneric::
checkGroupALQrateExceeded(double delta_alq) const
{
const auto &pairs =
group_info_.getWellGroups(well_name_);
for (const auto &[group_name, efficiency] : pairs) {
auto max_alq_opt = group_info_.maxAlq(group_name);
if (max_alq_opt) {
double alq =
group_info_.alqRate(group_name) + efficiency * delta_alq;
if (alq > *max_alq_opt) {
if (debug) {
const std::string msg = fmt::format(
"Group {} : alq {} exceeds max_alq {}. Stopping iteration",
group_name, alq, *max_alq_opt);
displayDebugMessage_(msg);
}
return true;
}
}
}
return false;
}
bool
GasLiftSingleWellGeneric::
checkGroupTotalRateExceeded(double delta_alq, double delta_gas_rate) const
{
const auto &pairs =
group_info_.getWellGroups(well_name_);
for (const auto &[group_name, efficiency] : pairs) {
auto max_total_rate_opt = group_info_.maxTotalGasRate(group_name);
if (max_total_rate_opt) {
double alq =
group_info_.alqRate(group_name) + efficiency * delta_alq;
double gas_rate =
group_info_.gasRate(group_name) + efficiency * delta_gas_rate;
if ( (alq + gas_rate) > *max_total_rate_opt) {
if (debug) {
const std::string msg = fmt::format(
"Group {} : total gas rate {} exceeds max_total_gas_rate {}. Stopping iteration",
group_name, alq + gas_rate, *max_total_rate_opt);
displayDebugMessage_(msg);
}
return true;
}
}
}
return false;
}
//
// bool checkEcoGradient(double gradient)
//
// - Determine if the gradient has reached the limit of the economic gradient.
//
// - If we are increasing lift gas, returns true if the gradient is smaller
// than or equal to the economic gradient,
//
// - If we are decreasing lift gas, returns true if the gradient is greater
// than or equal to the economic gradient. (I.e., we assume too much lift gas
// is being used and the gradient has become too small. We try to decrease
// lift gas until the gradient increases and reaches the economic gradient..)
//
bool
GasLiftSingleWellGeneric::OptimizeState::
checkEcoGradient(double gradient)
{
std::ostringstream ss;
bool result = false;
if (this->parent.debug) {
ss << "checking gradient: " << gradient;
}
if (this->increase) {
if (this->parent.debug) ss << " <= " << this->parent.eco_grad_ << " --> ";
if (gradient <= this->parent.eco_grad_) {
if (this->parent.debug) ss << "yes, stopping";
result = true;
}
else {
if (this->parent.debug) ss << "no, continue";
}
}
else { // decreasing lift gas
if (this->parent.debug) ss << " >= " << this->parent.eco_grad_ << " --> ";
if (gradient >= this->parent.eco_grad_) {
if (this->parent.debug) ss << "yes, stopping";
result = true;
}
else {
if (this->parent.debug) ss << "no, continue";
}
}
if (this->parent.debug) this->parent.displayDebugMessage_(ss.str());
return result;
}
bool
GasLiftSingleWellGeneric::OptimizeState::
checkRatesViolated(const LimitedRates& rates) const
{
if (!this->increase) {
if (rates.oil < 0) {
// The well is not flowing, and it will(?) not help to reduce lift
// gas further. Note that this assumes that the oil rates drops with
// decreasing lift gas.
this->parent.displayDebugMessage_(
"Negative oil rate detected while descreasing "
"lift gas. Stopping iteration.");
return true;
}
}
if (rates.limited()) {
if (this->parent.debug) {
const std::string well_or_group
= rates.limit_type == LimitedRates::LimitType::well ? "well" : "group";
std::string target_type;
std::string rate_type;
if (rates.oil_is_limited) {
target_type = GasLiftGroupInfo::rateToString(
*(rates.oil_limiting_target));
rate_type = "oil";
}
else if (rates.gas_is_limited) {
target_type = "gas";
rate_type = "gas";
}
else if (rates.water_is_limited) {
target_type = GasLiftGroupInfo::rateToString(
*(rates.water_limiting_target));
rate_type = "water";
}
const std::string msg = fmt::format(
"iteration {} : {} rate was limited due to {} {} target. "
"Stopping iteration",
this->it, rate_type, well_or_group, target_type);
this->parent.displayDebugMessage_(msg);
}
return true;
}
return false;
}
void
GasLiftSingleWellGeneric::OptimizeState::
debugShowIterationInfo(double alq)
{
const std::string msg = fmt::format("iteration {}, ALQ = {}", this->it, alq);
this->parent.displayDebugMessage_(msg);
}
// NOTE: When calculating the gradient, determine what the well would produce if
// the lift gas injection rate were increased by one increment. The
// production rates are adjusted if necessary to obey
// any rate or BHP limits that the well may be subject to. From this
// information, calculate the well's "weighted incremental
// gradient"
//
// TODO: What does it mean to "adjust the production rates" given a
// BHP limit?
//
double
GasLiftSingleWellGeneric::OptimizeState::
getBhpWithLimit()
{
auto [new_bhp, limited] = this->parent.getBhpWithLimit_(this->bhp);
if (limited) {
// TODO: is it possible that bhp falls below the limit when
// adding lift gas? I.e. if this->increase == true..
// TODO: we keep the current alq, but it should probably
// be adjusted since we changed computed bhp. But how?
// Stop iteration, but first check the economic gradient
// with the bhp_update. If the gradient looks OK (see the
// main optimize loop) we keep the current ALQ value.
this->stop_iteration = true;
}
return new_bhp;
}
/****************************************
* Methods declared in BasicRates
****************************************/
GasLiftSingleWellGeneric::BasicRates::
BasicRates(const LimitedRates& rates)
{
oil = rates.oil;
gas = rates.gas;
water = rates.water;
bhp_is_limited = rates.bhp_is_limited;
}
} // namespace Opm
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