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837f33e679
opm-simulators/opm/simulators/wells/GasLiftSingleWellGeneric.cpp
Håkon Hægland 837f33e679 Refactor some methods in GasLiftSingleWellGeneric. 
Refactor getOilRateWithGroupLimit_(), getGasRateWithGroupLimit_(),
getWaterRateWithGroupLimit_(), and getLiquidRateWithGroupLimit_() into
a single generic method called getRateWithGroupLimit_().
2021-12-20 23:08:31 +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/parser/eclipse/EclipseState/Schedule/GasLiftOpt.hpp>
#include <opm/parser/eclipse/EclipseState/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 Schedule& schedule,
const int report_step_idx,
GLiftSyncGroups &sync_groups
) :
deferred_logger_{deferred_logger}
, well_state_{well_state}
, group_state_{group_state}
, ecl_well_{ecl_well}
, summary_state_{summary_state}
, group_info_{group_info}
, sync_groups_{sync_groups}
, controls_{ecl_well_.productionControls(summary_state_)}
, num_phases_{well_state_.numPhases()}
, debug_{false} // extra debugging output
, 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 = getBhpWithLimit_(*bhp);
// TODO: What to do if BHP is limited?
std::vector<double> potentials(this->num_phases_, 0.0);
computeWellRates_(new_bhp.first, potentials);
auto [new_oil_rate, oil_is_limited] = getOilRateWithLimit_(potentials);
auto [new_gas_rate, gas_is_limited] = getGasRateWithLimit_(potentials);
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_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);
}
}
}
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(double delta_oil, double delta_gas, double delta_water) const
{
const auto &pairs =
this->group_info_.getWellGroups(this->well_name_);
for (const auto &[group_name, efficiency] : pairs) {
auto oil_target_opt = this->group_info_.oilTarget(group_name);
if (oil_target_opt) {
double oil_rate =
this->group_info_.oilRate(group_name) + efficiency * delta_oil;
if (oil_rate > *oil_target_opt) {
if (this->debug_) {
const std::string msg = fmt::format(
"Group {} : oil rate {} exceeds oil target {}. Stopping iteration",
group_name, oil_rate, *oil_target_opt);
displayDebugMessage_(msg);
}
return true;
}
}
auto gas_target_opt = this->group_info_.gasTarget(group_name);
if (gas_target_opt) {
double gas_rate =
this->group_info_.gasRate(group_name) + efficiency * delta_gas;
if (gas_rate > *gas_target_opt) {
if (this->debug_) {
const std::string msg = fmt::format(
"Group {} : gas rate {} exceeds gas target {}. Stopping iteration",
group_name, gas_rate, *gas_target_opt);
displayDebugMessage_(msg);
}
return true;
}
}
auto liquid_target_opt = this->group_info_.liquidTarget(group_name);
if (liquid_target_opt) {
double oil_rate =
this->group_info_.oilRate(group_name) + efficiency * delta_oil;
double water_rate =
this->group_info_.waterRate(group_name) + efficiency * delta_water;
double liquid_rate = oil_rate + water_rate;
if (liquid_rate > *liquid_target_opt) {
if (this->debug_) {
const std::string msg = fmt::format(
"Group {} : liquid rate {} exceeds liquid target {}. Stopping iteration",
group_name, liquid_rate, *liquid_target_opt);
this->displayDebugMessage_(msg);
}
return true;
}
}
auto water_target_opt = this->group_info_.waterTarget(group_name);
if (water_target_opt) {
double water_rate =
this->group_info_.waterRate(group_name) + efficiency * delta_water;
if (water_rate > *water_target_opt) {
if (this->debug_) {
const std::string msg = fmt::format(
"Group {} : water rate {} exceeds water target {}. Stopping iteration",
group_name, water_rate, *water_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::
checkWellRatesViolated_(
std::vector<double>& potentials,
const std::function<bool(double, double, const std::string &)>& callback,
bool increase)
{
if (!increase) {
auto oil_rate = -potentials[this->oil_pos_];
if (oil_rate < 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.
displayDebugMessage_("Negative oil rate detected while descreasing "
"lift gas. Stopping iteration.");
return true;
}
}
// TODO: the below checks could probably be skipped if we are decreasing
// lift gas (provided we can assume that rates declines monotonically with
// decreasing lift gas).
if (this->controls_.hasControl(Well::ProducerCMode::ORAT)) {
auto oil_rate = -potentials[this->oil_pos_];
if (callback(oil_rate, this->controls_.oil_rate, "oil"))
return true;
}
if (this->controls_.hasControl(Well::ProducerCMode::WRAT)) {
auto water_rate = -potentials[this->water_pos_];
if (callback(water_rate, this->controls_.water_rate, "water"))
return true;
}
if (this->controls_.hasControl(Well::ProducerCMode::GRAT)) {
auto gas_rate = -potentials[this->gas_pos_];
if (callback(gas_rate, this->controls_.gas_rate, "gas"))
return true;
}
if (this->controls_.hasControl(Well::ProducerCMode::LRAT)) {
auto oil_rate = -potentials[this->oil_pos_];
auto water_rate = -potentials[this->water_pos_];
auto liq_rate = oil_rate + water_rate;
if (callback(liq_rate, this->controls_.liquid_rate, "liquid"))
return true;
}
// TODO: Also check RESV, see checkIndividualContraints() in
// WellInterface_impl.hpp
// TODO: Check group contraints?
return false;
}
bool
GasLiftSingleWellGeneric::
computeInitialWellRates_(std::vector<double>& potentials)
{
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);
}
computeWellRates_(*bhp, potentials);
{
const std::string msg = fmt::format(
"computed initial well potentials given bhp, "
"oil: {}, gas: {}, water: {}",
-potentials[this->oil_pos_],
-potentials[this->gas_pos_],
-potentials[this->water_pos_]);
displayDebugMessage_(msg);
}
return true;
}
else {
displayDebugMessage_("Aborting optimization.");
return false;
}
}
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);
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 {
std::vector<double> potentials(this->num_phases_, 0.0);
computeWellRates_(*bhp_at_thp_limit, potentials, /*debug_out=*/false);
auto oil_rate = -potentials[this->oil_pos_];
auto gas_rate = -potentials[this->gas_pos_];
const std::string msg = fmt::format(
fmt_fmt2, alq, *bhp_at_thp_limit, oil_rate, gas_rate);
displayDebugMessage_(msg);
}
alq += this->increment_;
}
}
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 std::vector<double>& potentials) const
{
double new_rate = -potentials[this->gas_pos_];
bool limit = false;
if (this->controls_.hasControl(Well::ProducerCMode::GRAT)) {
auto target = this->controls_.gas_rate;
if (new_rate > target) {
new_rate = target;
limit = true;
}
}
return { new_rate, limit};
}
std::pair<double, bool>
GasLiftSingleWellGeneric::
getWaterRateWithLimit_(const std::vector<double>& potentials) const
{
double new_rate = -potentials[this->water_pos_];
bool limit = false;
if (this->controls_.hasControl(Well::ProducerCMode::WRAT)) {
auto target = this->controls_.water_rate;
if (new_rate > target) {
new_rate = target;
limit = true;
}
}
return { new_rate, limit};
}
// 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 std::vector<double>& potentials) const
{
double oil_rate = -potentials[this->oil_pos_];
double new_rate = oil_rate;
bool limited = false;
if (this->controls_.hasControl(Well::ProducerCMode::ORAT)) {
auto target = this->controls_.oil_rate;
if (oil_rate > target) {
const std::string msg = fmt::format("limiting oil rate to target: "
"computed rate: {}, target: {}", new_rate, target);
displayDebugMessage_(msg);
new_rate = target;
limited = true;
}
}
if (this->controls_.hasControl(Well::ProducerCMode::LRAT)) {
auto target = this->controls_.liquid_rate;
double water_rate = -potentials[this->water_pos_];
double liq_rate = oil_rate + water_rate;
if (liq_rate > target) {
double oil_fraction = oil_rate / liq_rate;
new_rate = std::min(new_rate, oil_fraction * target);
limited = true;
const std::string msg = fmt::format(
"limiting oil rate due to LRAT target: "
"computed rate: {}, target: {}", oil_rate, new_rate);
displayDebugMessage_(msg);
}
}
return { new_rate, limited};
}
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_(double new_oil_rate, double oil_rate,
double new_water_rate, 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;
new_oil_rate = oil_rate + oil_fraction * delta_liquid;
new_water_rate = water_rate + (1.0 - oil_fraction) * delta_liquid;
}
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);
assert(gr_rate_temp <= gr_target_temp);
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 (this->debug_ && group_name) {
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::tuple<double,double,double, bool, bool,bool>
GasLiftSingleWellGeneric::
getInitialRatesWithLimit_(const std::vector<double>& potentials)
{
auto [oil_rate, oil_is_limited] = getOilRateWithLimit_(potentials);
auto [gas_rate, gas_is_limited] = getGasRateWithLimit_(potentials);
auto [water_rate, water_is_limited] = getWaterRateWithLimit_(potentials);
if (oil_is_limited) {
const std::string msg = fmt::format(
"initial oil rate was limited to: {}", oil_rate);
displayDebugMessage_(msg);
}
if (gas_is_limited) {
const std::string msg = fmt::format(
"initial gas rate was limited to: {}", gas_rate);
displayDebugMessage_(msg);
}
if (water_is_limited) {
const std::string msg = fmt::format(
"initial water rate was limited to: {}", water_rate);
displayDebugMessage_(msg);
}
return std::make_tuple(oil_rate, gas_rate, water_rate, oil_is_limited, gas_is_limited, water_is_limited);
}
std::tuple<double,double,bool,bool,double>
GasLiftSingleWellGeneric::
increaseALQtoPositiveOilRate_(double alq,
double oil_rate,
double gas_rate,
bool oil_is_limited,
bool gas_is_limited,
std::vector<double>& potentials)
{
bool stop_iteration = false;
double temp_alq = alq;
while(!stop_iteration) {
temp_alq += this->increment_;
if (temp_alq > this->max_alq_) break;
auto bhp_opt = computeBhpAtThpLimit_(temp_alq);
if (!bhp_opt) break;
alq = temp_alq;
auto bhp_this = getBhpWithLimit_(*bhp_opt);
computeWellRates_(bhp_this.first, potentials);
oil_rate = -potentials[this->oil_pos_];
if (oil_rate > 0) break;
}
std::tie(oil_rate, oil_is_limited) = getOilRateWithLimit_(potentials);
std::tie(gas_rate, gas_is_limited) = getGasRateWithLimit_(potentials);
return std::make_tuple(oil_rate, gas_rate, oil_is_limited, gas_is_limited, alq);
}
std::tuple<double,double,bool,bool,double>
GasLiftSingleWellGeneric::
increaseALQtoMinALQ_(double alq,
double oil_rate,
double gas_rate,
bool oil_is_limited,
bool gas_is_limited,
std::vector<double>& potentials)
{
auto min_alq = this->min_alq_;
assert(min_alq >= 0);
assert(alq < min_alq);
assert(min_alq < this->max_alq_);
bool stop_iteration = false;
double temp_alq = alq;
while(!stop_iteration) {
temp_alq += this->increment_;
if (temp_alq >= min_alq) break;
auto bhp_opt = computeBhpAtThpLimit_(temp_alq);
if (!bhp_opt) break;
alq = temp_alq;
auto bhp_this = getBhpWithLimit_(*bhp_opt);
computeWellRates_(bhp_this.first, potentials);
std::tie(oil_rate, oil_is_limited) = getOilRateWithLimit_(potentials);
std::tie(gas_rate, gas_is_limited) = getGasRateWithLimit_(potentials);
if (oil_is_limited || gas_is_limited) break;
}
return std::make_tuple(oil_rate, gas_rate, oil_is_limited, gas_is_limited, 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::tuple<double,double,double,double,bool,bool,bool>
GasLiftSingleWellGeneric::
maybeAdjustALQbeforeOptimizeLoop_(
bool increase, double alq, double oil_rate, double gas_rate, double water_rate,
bool oil_is_limited, bool gas_is_limited,bool water_is_limited,
std::vector<double> &potentials)
{
double orig_alq = alq;
if (this->debug_) {
const std::string msg = fmt::format("initial ALQ: {}", alq);
displayDebugMessage_(msg);
}
if (!increase && ( oil_is_limited || water_is_limited || gas_is_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.
double reduced_oil_rate, reduced_gas_rate, reduced_water_rate, reduced_alq;
std::tie(reduced_oil_rate, reduced_gas_rate, reduced_water_rate, oil_is_limited, gas_is_limited, water_is_limited, reduced_alq) =
reduceALQtoWellTarget_(alq, oil_rate, gas_rate, water_rate,
oil_is_limited, gas_is_limited, water_is_limited, potentials);
// potentially reduce alq if group control is violated
double reduced2_oil_rate, reduced2_gas_rate, reduced2_water_rate, reduced2_alq;
std::tie(reduced2_oil_rate, reduced2_gas_rate,
reduced2_water_rate, reduced2_alq)
= reduceALQtoGroupTarget(
alq, oil_rate, gas_rate, water_rate, potentials);
oil_rate = std::min(reduced_oil_rate, reduced2_oil_rate);
gas_rate = std::min(reduced_gas_rate, reduced2_gas_rate);
water_rate = std::min(reduced_water_rate, reduced2_water_rate);
alq = std::min(reduced_alq, reduced2_alq);
} else {
if (increase && oil_rate < 0) {
// NOTE: Try to increase ALQ up to a value where oil_rate is positive
std::tie(oil_rate, gas_rate, oil_is_limited, gas_is_limited, alq) =
increaseALQtoPositiveOilRate_(alq, oil_rate,
gas_rate, oil_is_limited, gas_is_limited, potentials);
}
if (increase && (this->min_alq_> 0) && (alq < this->min_alq_)) {
// NOTE: Try to increase ALQ up to the minimum limit without checking
// the economic gradient..
std::tie(oil_rate, gas_rate, oil_is_limited, gas_is_limited, alq) =
increaseALQtoMinALQ_(alq, oil_rate, gas_rate,
oil_is_limited, gas_is_limited, potentials);
}
}
if (this->debug_ && (orig_alq != alq)) {
const std::string msg = fmt::format("adjusted ALQ to: {}", alq);
displayDebugMessage_(msg);
}
return std::make_tuple(oil_rate, gas_rate, water_rate, alq, oil_is_limited, gas_is_limited, water_is_limited);
}
std::tuple<double,double,double,double>
GasLiftSingleWellGeneric::
reduceALQtoGroupTarget(double alq,
double oil_rate,
double gas_rate,
double water_rate,
std::vector<double>& potentials) const
{
bool stop_this_iteration = true;
const auto &pairs =
this->group_info_.getWellGroups(this->well_name_);
for (const auto &groups : pairs) {
if (!this->group_state_.has_production_control(groups.first))
continue;
const auto& current_control = this->group_state_.production_control(groups.first);
if(current_control == Group::ProductionCMode::ORAT
|| current_control == Group::ProductionCMode::LRAT
|| current_control == Group::ProductionCMode::WRAT
|| current_control == Group::ProductionCMode::GRAT){
stop_this_iteration = false;
displayDebugMessage_("Reducing ALQ to meet groups target before iteration starts.");
break;
}
}
double temp_alq = alq;
double oil_rate_orig = oil_rate;
double gas_rate_orig = gas_rate;
double water_rate_orig = water_rate;
while(!stop_this_iteration) {
temp_alq -= this->increment_;
if (temp_alq <= 0) break;
auto bhp_opt = computeBhpAtThpLimit_(temp_alq);
if (!bhp_opt) break;
auto bhp_this = getBhpWithLimit_(*bhp_opt);
computeWellRates_(bhp_this.first, potentials);
oil_rate = -potentials[this->oil_pos_];
gas_rate = -potentials[this->gas_pos_];
water_rate = -potentials[this->water_pos_];
double delta_oil = oil_rate - oil_rate_orig;
double delta_gas = gas_rate - gas_rate_orig;
double delta_water = water_rate - water_rate_orig;
if (!checkGroupTargetsViolated(delta_oil, delta_gas, delta_water)) {
break;
}
alq = temp_alq;
}
return std::make_tuple(oil_rate, gas_rate, water_rate, alq);
}
std::tuple<double,double,double, bool, bool,bool,double>
GasLiftSingleWellGeneric::
reduceALQtoWellTarget_(double alq,
double oil_rate,
double gas_rate,
double water_rate,
bool oil_is_limited,
bool gas_is_limited,
bool water_is_limited,
std::vector<double>& potentials)
{
displayDebugMessage_("Reducing ALQ to meet well target before iteration starts..");
double orig_oil_rate = oil_rate;
double orig_alq = alq;
// check well targets
bool stop_iteration = false;
auto limiting_control = Well::ProducerCMode::NONE;
double temp_alq = alq;
while(!stop_iteration) {
temp_alq -= this->increment_;
if (temp_alq <= 0) break;
auto bhp_opt = computeBhpAtThpLimit_(temp_alq);
if (!bhp_opt) break;
auto bhp_this = getBhpWithLimit_(*bhp_opt);
computeWellRates_(bhp_this.first, potentials);
oil_rate = -potentials[this->oil_pos_];
water_rate = -potentials[this->water_pos_];
gas_rate = -potentials[this->gas_pos_];
if (oil_is_limited && this->controls_.hasControl(Well::ProducerCMode::ORAT) && oil_rate < this->controls_.oil_rate) {
limiting_control = Well::ProducerCMode::ORAT;
break;
}
if (oil_is_limited && this->controls_.hasControl(Well::ProducerCMode::LRAT) && (oil_rate + water_rate) < this->controls_.liquid_rate) {
limiting_control = Well::ProducerCMode::LRAT;
break;
}
if (gas_is_limited && gas_rate < this->controls_.gas_rate) {
limiting_control = Well::ProducerCMode::GRAT;
break;
}
if (water_is_limited && water_rate < this->controls_.water_rate) {
limiting_control = Well::ProducerCMode::WRAT;
break;
}
alq = temp_alq;
}
std::tie(oil_rate, oil_is_limited) = getOilRateWithLimit_(potentials);
std::tie(gas_rate, gas_is_limited) = getGasRateWithLimit_(potentials);
std::tie(water_rate, water_is_limited) = getWaterRateWithLimit_(potentials);
if (this->debug_) {
assert( alq <= orig_alq );
std::string type;
double target = 0.0;
double rate = 0.0;
if (limiting_control == Well::ProducerCMode::ORAT) {
rate = oil_rate;
target = this->controls_.oil_rate;
type = "ORAT";
} else if(limiting_control == Well::ProducerCMode::LRAT) {
rate = oil_rate + water_rate;
target = this->controls_.liquid_rate;
type = "LRAT";
} else if (limiting_control == Well::ProducerCMode::WRAT) {
rate = water_rate;
target = this->controls_.water_rate;
type = "WRAT";
} else if (limiting_control == Well::ProducerCMode::GRAT) {
rate = gas_rate;
target = this->controls_.gas_rate;
type = "GRAT";
}
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 (rate, alq) from ({}, {}) to ({}, {}) to meet {} target "
"at {}. ", orig_oil_rate, orig_alq, rate, alq, type, target);
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. "
" {} is {} and target is {}", orig_alq, type, rate, target);
displayDebugMessage_(msg);
}
}
return std::make_tuple(oil_rate, gas_rate, water_rate,
oil_is_limited, gas_is_limited, water_is_limited, 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)
{
std::vector<double> potentials(this->num_phases_, 0.0);
std::unique_ptr<GasLiftWellState> ret_value; // nullptr initially
if (!computeInitialWellRates_(potentials)) return ret_value;
bool alq_is_limited = false;
bool oil_is_limited = false;
bool gas_is_limited = false;
bool water_is_limited = false;
double oil_rate, gas_rate, water_rate;
std::tie(oil_rate, gas_rate, water_rate, oil_is_limited, gas_is_limited, water_is_limited) =
getInitialRatesWithLimit_(potentials);
//if (this->debug_) debugShowBhpAlqTable_();
if (this->debug_) debugShowAlqIncreaseDecreaseCounts_();
if (this->debug_) debugShowTargets_();
bool success = false; // did we succeed to increase alq?
auto cur_alq = this->orig_alq_;
double new_oil_rate, new_gas_rate, new_water_rate, new_alq;
bool new_oil_is_limited, new_gas_is_limited, new_water_is_limited;
std::tie(new_oil_rate, new_gas_rate, new_water_rate, new_alq,
new_oil_is_limited, new_gas_is_limited, new_water_is_limited)
= maybeAdjustALQbeforeOptimizeLoop_(
increase, cur_alq, oil_rate, gas_rate, water_rate,
oil_is_limited, gas_is_limited, water_is_limited, potentials);
double delta_oil = 0.0;
double delta_gas = 0.0;
double delta_alq = 0.0;
double delta_water = 0.0;
OptimizeState state {*this, increase};
if (checkInitialALQmodified_(new_alq, cur_alq)) {
delta_oil = new_oil_rate - oil_rate;
delta_gas = new_gas_rate - gas_rate;
delta_water = new_water_rate - water_rate;
delta_alq = new_alq - cur_alq;
if (!(checkGroupTargetsViolated(delta_oil, delta_gas, delta_water)) &&
!(state.checkGroupALQrateExceeded(delta_alq)))
{
oil_rate = new_oil_rate;
gas_rate = new_gas_rate;
water_rate = new_water_rate;
oil_is_limited = new_oil_is_limited;
gas_is_limited = new_gas_is_limited;
water_is_limited = new_water_is_limited;
cur_alq = new_alq;
success = true;
}
else {
state.stop_iteration = true;
}
}
// we only iterate if well is under thp control
if (!state.checkThpControl()) {
state.stop_iteration = true;
}
auto temp_alq = cur_alq;
if (this->debug_) debugShowStartIteration_(temp_alq, increase, oil_rate);
while (!state.stop_iteration && (++state.it <= this->max_iterations_)) {
if (!increase && state.checkNegativeOilRate(oil_rate)) break;
if (state.checkWellRatesViolated(potentials)) break;
if (checkGroupTargetsViolated(delta_oil, delta_gas, delta_water)) break;
if (state.checkAlqOutsideLimits(temp_alq, oil_rate)) break;
std::optional<double> alq_opt;
std::tie(alq_opt, alq_is_limited)
= state.addOrSubtractAlqIncrement(temp_alq);
if (!alq_opt) break;
delta_alq = *alq_opt - temp_alq;
if (state.checkGroupALQrateExceeded(delta_alq)) break;
temp_alq = *alq_opt;
if (this->debug_) state.debugShowIterationInfo(temp_alq);
if (!state.computeBhpAtThpLimit(temp_alq)) break;
// NOTE: if BHP is below limit, we set state.stop_iteration = true
auto bhp = state.getBhpWithLimit();
computeWellRates_(bhp, potentials);
std::tie(new_oil_rate, new_oil_is_limited) = getOilRateWithLimit_(potentials);
std::tie(new_oil_rate, new_oil_is_limited) = getOilRateWithGroupLimit_(new_oil_rate, oil_rate);
/* if (this->debug_abort_if_decrease_and_oil_is_limited_) {
if (oil_is_limited && !increase) {
// if oil is limited we do not want to decrease
displayDebugMessage_(
"decreasing ALQ and oil is limited -> aborting iteration");
break;
}
}
*/
std::tie(new_gas_rate, new_gas_is_limited) = getGasRateWithLimit_(potentials);
std::tie(new_gas_rate, new_gas_is_limited) = getGasRateWithGroupLimit_(new_gas_rate, gas_rate);
std::tie(new_water_rate, new_water_is_limited) = getWaterRateWithLimit_(potentials);
std::tie(new_water_rate, new_water_is_limited) = getWaterRateWithGroupLimit_(new_water_rate, water_rate);
std::tie(new_oil_rate, new_water_rate, new_oil_is_limited, new_water_is_limited)
= getLiquidRateWithGroupLimit_(new_oil_rate, oil_rate, new_water_rate, water_rate);
/* 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(
oil_rate, new_oil_rate, gas_rate, new_gas_rate);
if (this->debug_)
debugCheckNegativeGradient_(
gradient, cur_alq, temp_alq, oil_rate, new_oil_rate,
gas_rate, new_gas_rate, increase);
if (state.checkEcoGradient(gradient)) break;
cur_alq = temp_alq;
success = true;
delta_oil = new_oil_rate - oil_rate;
delta_gas = new_gas_rate - gas_rate;
delta_water = new_water_rate - water_rate;
oil_rate = new_oil_rate;
gas_rate = new_gas_rate;
water_rate = new_water_rate;
oil_is_limited = new_oil_is_limited;
gas_is_limited = new_gas_is_limited;
water_is_limited = new_water_is_limited;
state.updateGroupRates(delta_oil, delta_gas, delta_water, 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>(oil_rate, oil_is_limited,
gas_rate, gas_is_limited, cur_alq, alq_is_limited, 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.");
}
}
}
// 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 {
// 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::
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.";
return true;
}
else if ( alq < 0 ) {
ss << "Negative ALQ: " << alq << ". Stopping iteration.";
return 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
// checkNegativeOilRate().
// - We also know that the rate limit was not exceeded since that was
// checked by checkWellRatesViolated()
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::OptimizeState::
checkGroupALQrateExceeded(double delta_alq)
{
const auto &pairs =
this->parent.group_info_.getWellGroups(this->parent.well_name_);
for (const auto &[group_name, efficiency] : pairs) {
auto max_alq_opt = this->parent.group_info_.maxAlq(group_name);
if (max_alq_opt) {
double alq =
this->parent.group_info_.alqRate(group_name) + efficiency * delta_alq;
if (alq > *max_alq_opt) {
if (this->parent.debug_) {
const std::string msg = fmt::format(
"Group {} : alq {} exceeds max_alq {}. Stopping iteration",
group_name, alq, *max_alq_opt);
this->parent.displayDebugMessage_(msg);
}
return true;
}
}
}
return false;
}
bool
GasLiftSingleWellGeneric::OptimizeState::
checkNegativeOilRate(double oil_rate)
{
if (oil_rate < 0) {
const std::string msg = fmt::format(
"Negative oil rate {}. Stopping iteration", oil_rate);
this->parent.displayDebugMessage_(msg);
return true;
}
return false;
}
bool
GasLiftSingleWellGeneric::OptimizeState::
checkThpControl()
{
const int well_index = this->parent.well_state_.index(this->parent.well_name_).value();
const Well::ProducerCMode& control_mode = this->parent.well_state_.well(well_index).production_cmode;
return control_mode == Well::ProducerCMode::THP;
}
//
// 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::
checkRate(double rate, double limit, const std::string& rate_str) const
{
if (limit < rate) {
if (this->parent.debug_) {
const std::string msg = fmt::format(
"iteration {} : {} rate {} exceeds target {}. Stopping iteration",
this->it, rate_str, rate, limit);
this->parent.displayDebugMessage_(msg);
}
return true;
}
return false;
}
bool
GasLiftSingleWellGeneric::OptimizeState::
checkWellRatesViolated(std::vector<double>& potentials)
{
auto callback = [*this](double rate, double limit, const std::string& rate_str)
-> bool
{ return this->checkRate(rate, limit, rate_str); };
return this->parent.checkWellRatesViolated_(potentials, callback, this->increase);
}
bool
GasLiftSingleWellGeneric::OptimizeState::
computeBhpAtThpLimit(double alq)
{
auto bhp_opt = this->parent.computeBhpAtThpLimit_(alq);
if (bhp_opt) {
this->bhp = *bhp_opt;
return true;
}
else {
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;
}
void
GasLiftSingleWellGeneric::OptimizeState::
updateGroupRates(double delta_oil, double delta_gas, double delta_water, double delta_alq)
{
const auto &pairs =
this->parent.group_info_.getWellGroups(this->parent.well_name_);
for (const auto &[group_name, efficiency] : pairs) {
int idx = this->parent.group_info_.getGroupIdx(group_name);
this->parent.sync_groups_.insert(idx);
this->parent.group_info_.update(group_name,
efficiency * delta_oil, efficiency * delta_gas, efficiency * delta_water, efficiency * delta_alq);
}
}
} // namespace Opm
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