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opm-simulators/opm/simulators/wells/WellBhpThpCalculator.cpp
Paul f9d82c6042 adressing several reviewers comments
2024-07-03 16:55:00 +02:00

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/*
Copyright 2017 SINTEF Digital, Mathematics and Cybernetics.
Copyright 2017 Statoil ASA.
Copyright 2018 IRIS
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/WellBhpThpCalculator.hpp>
#include <opm/common/utility/numeric/RootFinders.hpp>
#include <opm/input/eclipse/Schedule/VFPInjTable.hpp>
#include <opm/input/eclipse/Schedule/Well/Well.hpp>
#include <opm/input/eclipse/Units/Units.hpp>
#include <opm/input/eclipse/Schedule/Well/WVFPDP.hpp>
#include <opm/material/densead/Evaluation.hpp>
#include <opm/simulators/utils/BlackoilPhases.hpp>
#include <opm/simulators/utils/DeferredLoggingErrorHelpers.hpp>
#include <opm/simulators/wells/VFPProperties.hpp>
#include <opm/simulators/wells/WellHelpers.hpp>
#include <opm/simulators/wells/WellInterfaceGeneric.hpp>
#include <cassert>
#include <cmath>
#include <optional>
#include <fmt/format.h>
static constexpr bool extraBhpAtThpLimitOutput = false;
static constexpr bool extraThpFromBhpOutput = false;
namespace Opm {
template<class Scalar>
bool WellBhpThpCalculator<Scalar>::
wellHasTHPConstraints(const SummaryState& summaryState) const
{
const auto& well_ecl = well_.wellEcl();
if (well_ecl.isInjector()) {
const auto controls = well_ecl.injectionControls(summaryState);
if (controls.hasControl(Well::InjectorCMode::THP))
return true;
}
if (well_ecl.isProducer()) {
const auto controls = well_ecl.productionControls(summaryState);
if (controls.hasControl(Well::ProducerCMode::THP))
return true;
}
return false;
}
template<class Scalar>
Scalar WellBhpThpCalculator<Scalar>::
getTHPConstraint(const SummaryState& summaryState) const
{
const auto& well_ecl = well_.wellEcl();
if (well_ecl.isInjector()) {
const auto& controls = well_ecl.injectionControls(summaryState);
return controls.thp_limit;
}
if (well_ecl.isProducer( )) {
const auto& controls = well_ecl.productionControls(summaryState);
return controls.thp_limit;
}
return 0.0;
}
template<class Scalar>
Scalar WellBhpThpCalculator<Scalar>::
mostStrictBhpFromBhpLimits(const SummaryState& summaryState) const
{
const auto& well_ecl = well_.wellEcl();
if (well_ecl.isInjector()) {
const auto& controls = well_ecl.injectionControls(summaryState);
return controls.bhp_limit;
}
if (well_ecl.isProducer( )) {
const auto& controls = well_ecl.productionControls(summaryState);
return controls.bhp_limit;
}
return 0.0;
}
template<class Scalar>
Scalar WellBhpThpCalculator<Scalar>::
calculateThpFromBhp(const std::vector<Scalar>& rates,
const Scalar bhp,
const Scalar rho,
const std::optional<Scalar>& alq,
const Scalar thp_limit,
DeferredLogger& deferred_logger) const
{
assert(int(rates.size()) == 3); // the vfp related only supports three phases now.
static constexpr int Water = BlackoilPhases::Aqua;
static constexpr int Oil = BlackoilPhases::Liquid;
static constexpr int Gas = BlackoilPhases::Vapour;
const Scalar aqua = rates[Water];
const Scalar liquid = rates[Oil];
const Scalar vapour = rates[Gas];
// pick the density in the top layer
Scalar thp = 0.0;
const int table_id = well_.wellEcl().vfp_table_number();
if (well_.isInjector()) {
assert(!alq.has_value());
const Scalar vfp_ref_depth = well_.vfpProperties()->getInj()->getTable(table_id).getDatumDepth();
const Scalar dp = wellhelpers::computeHydrostaticCorrection(well_.refDepth(), vfp_ref_depth, rho, well_.gravity());
auto thp_func =
[this, table_id, aqua, liquid, vapour, dp](
const Scalar bhp_value, const Scalar pressure_loss) {
return this->well_.vfpProperties()->getInj()->thp(
table_id, aqua, liquid, vapour, bhp_value + dp - pressure_loss);
};
thp = findThpFromBhpIteratively(thp_func, bhp, thp_limit, dp, deferred_logger);
}
else if (well_.isProducer()) {
const Scalar vfp_ref_depth = well_.vfpProperties()->getProd()->getTable(table_id).getDatumDepth();
const Scalar dp = wellhelpers::computeHydrostaticCorrection(well_.refDepth(), vfp_ref_depth, rho, well_.gravity());
const bool use_vfpexp = well_.useVfpExplicit();
const Scalar wfr = well_.vfpProperties()->getExplicitWFR(table_id, well_.indexOfWell());
const Scalar gfr = well_.vfpProperties()->getExplicitGFR(table_id, well_.indexOfWell());
auto thp_func =
[this, table_id, aqua, liquid, vapour, dp, &alq, wfr, gfr, use_vfpexp]
(const Scalar bhp_value, const Scalar pressure_loss) {
return this->well_.vfpProperties()->getProd()->thp(
table_id, aqua, liquid, vapour, bhp_value + dp - pressure_loss, alq.value(), wfr, gfr, use_vfpexp);
};
thp = findThpFromBhpIteratively(thp_func, bhp, thp_limit, dp, deferred_logger);
}
else {
OPM_DEFLOG_THROW(std::logic_error, "Expected INJECTOR or PRODUCER well", deferred_logger);
}
return thp;
}
template<class Scalar>
Scalar WellBhpThpCalculator<Scalar>::
findThpFromBhpIteratively(const std::function<Scalar(const Scalar, const Scalar)>& thp_func,
const Scalar bhp,
const Scalar thp_limit,
const Scalar dp,
DeferredLogger& deferred_logger) const
{
auto pressure_loss = getVfpBhpAdjustment(bhp + dp, thp_limit);
auto thp = thp_func(bhp, pressure_loss);
const Scalar tolerance = 1e-5 * unit::barsa;
bool do_iterate = true;
int it = 1;
int max_iterations = 50;
while (do_iterate) {
if (it > max_iterations) {
break;
}
Scalar thp_prev = thp;
pressure_loss = getVfpBhpAdjustment(bhp + dp - pressure_loss, thp_prev);
thp = thp_func(bhp, pressure_loss);
auto error = std::fabs(thp - thp_prev);
if (extraThpFromBhpOutput) {
const std::string msg = fmt::format(
"findThpFromBhpIteratively(): iteration {}, thp = {}, bhp = {}, "
"pressure_loss = {}, error = {}", it, thp, bhp+dp-pressure_loss, pressure_loss, error);
deferred_logger.debug(msg);
}
if (std::fabs(thp - thp_prev) < tolerance) {
break;
}
it++;
}
return thp;
}
template<class Scalar>
std::optional<Scalar>
WellBhpThpCalculator<Scalar>::
computeBhpAtThpLimitProd(const std::function<std::vector<Scalar>(const Scalar)>& frates,
const SummaryState& summary_state,
const Scalar maxPerfPress,
const Scalar rho,
const Scalar alq_value,
const Scalar thp_limit,
DeferredLogger& deferred_logger) const
{
// Given a VFP function returning bhp as a function of phase
// rates and thp:
// fbhp(rates, thp),
// a function extracting the particular flow rate used for VFP
// lookups:
// flo(rates)
// and the inflow function (assuming the reservoir is fixed):
// frates(bhp)
// we want to solve the equation:
// fbhp(frates(bhp, thplimit)) - bhp = 0
// for bhp.
//
// This may result in 0, 1 or 2 solutions. If two solutions,
// the one corresponding to the lowest bhp (and therefore
// highest rate) should be returned.
static constexpr int Water = BlackoilPhases::Aqua;
static constexpr int Oil = BlackoilPhases::Liquid;
static constexpr int Gas = BlackoilPhases::Vapour;
// Make the fbhp() function.
const auto& controls = well_.wellEcl().productionControls(summary_state);
const auto& table = well_.vfpProperties()->getProd()->getTable(controls.vfp_table_number);
const Scalar vfp_ref_depth = table.getDatumDepth();
const Scalar dp = wellhelpers::computeHydrostaticCorrection(well_.refDepth(),
vfp_ref_depth,
rho,
well_.gravity());
auto fbhp = [this, &controls, thp_limit, dp, alq_value](const std::vector<Scalar>& rates) {
assert(rates.size() == 3);
const auto& wfr = well_.vfpProperties()->getExplicitWFR(controls.vfp_table_number,
well_.indexOfWell());
const auto& gfr = well_.vfpProperties()->getExplicitGFR(controls.vfp_table_number,
well_.indexOfWell());
const bool use_vfpexp = well_.useVfpExplicit();
const Scalar bhp = well_.vfpProperties()->getProd()->bhp(controls.vfp_table_number,
rates[Water],
rates[Oil],
rates[Gas],
thp_limit,
alq_value,
wfr,
gfr,
use_vfpexp);
return bhp - dp + getVfpBhpAdjustment(bhp, thp_limit);
};
// Make the flo() function.
auto flo = [&table](const std::vector<Scalar>& rates) {
return detail::getFlo(table, rates[Water], rates[Oil], rates[Gas]);
};
// Find the bhp-point where production becomes nonzero.
auto fflo = [&flo, &frates](Scalar bhp) { return flo(frates(bhp)); };
auto bhp_max = this->bhpMax(fflo,
controls.bhp_limit,
maxPerfPress,
table.getFloAxis().front(),
deferred_logger);
// could not solve for the bhp-point, we could not continue to find the bhp
if (!bhp_max.has_value()) {
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE_INOPERABLE",
"Robust bhp(thp) solve failed due to not being able to "
"find bhp-point where production becomes non-zero for well " + well_.name());
return std::nullopt;
}
const std::array<Scalar, 2> range {static_cast<Scalar>(controls.bhp_limit), *bhp_max};
return this->computeBhpAtThpLimit(frates, fbhp, range, deferred_logger);
}
template<class Scalar>
std::optional<Scalar>
WellBhpThpCalculator<Scalar>::
computeBhpAtThpLimitInj(const std::function<std::vector<Scalar>(const Scalar)>& frates,
const SummaryState& summary_state,
const Scalar rho,
const Scalar flo_rel_tol,
const int max_iteration,
const bool throwOnError,
DeferredLogger& deferred_logger) const
{
if (throwOnError) {
return computeBhpAtThpLimitInjImpl<ThrowOnError>(frates, summary_state,
rho, flo_rel_tol,
max_iteration, deferred_logger);
} else {
return computeBhpAtThpLimitInjImpl<WarnAndContinueOnError>(frates, summary_state,
rho, flo_rel_tol,
max_iteration, deferred_logger);
}
}
template<class Scalar>
void WellBhpThpCalculator<Scalar>::
updateThp(const Scalar rho,
const bool stop_or_zero_rate_target,
const std::function<Scalar()>& alq_value,
const std::array<unsigned,3>& active,
WellState<Scalar>& well_state,
const SummaryState& summary_state,
DeferredLogger& deferred_logger) const
{
static constexpr int Gas = BlackoilPhases::Vapour;
static constexpr int Oil = BlackoilPhases::Liquid;
static constexpr int Water = BlackoilPhases::Aqua;
auto& ws = well_state.well(well_.indexOfWell());
// When there is no vaild VFP table provided, we set the thp to be zero.
if (!well_.isVFPActive(deferred_logger) || stop_or_zero_rate_target) {
ws.thp = 0;
return;
}
// For THP controlled wells, we know the thp value
bool thp_controlled = well_.isInjector() ? ws.injection_cmode == Well::InjectorCMode::THP:
ws.production_cmode == Well::ProducerCMode::THP;
if (thp_controlled) {
return;
}
// the well is under other control types, we calculate the thp based on bhp and rates
std::vector<Scalar> rates(3, 0.0);
const PhaseUsage& pu = well_.phaseUsage();
if (active[Water]) {
rates[ Water ] = ws.surface_rates[pu.phase_pos[ Water ] ];
}
if (active[Oil]) {
rates[ Oil ] = ws.surface_rates[pu.phase_pos[ Oil ] ];
}
if (active[Gas]) {
rates[ Gas ] = ws.surface_rates[pu.phase_pos[ Gas ] ];
}
const std::optional<Scalar> alq = this->well_.isProducer() ? std::optional<Scalar>(alq_value()) : std::nullopt;
const Scalar thp_limit = well_.getTHPConstraint(summary_state);
ws.thp = this->calculateThpFromBhp(rates, ws.bhp, rho, alq, thp_limit, deferred_logger);
}
template<class Scalar>
template<class EvalWell>
EvalWell WellBhpThpCalculator<Scalar>::
calculateBhpFromThp(const WellState<Scalar>& well_state,
const std::vector<EvalWell>& rates,
const Well& well,
const SummaryState& summaryState,
const Scalar rho,
DeferredLogger& deferred_logger) const
{
// TODO: when well is under THP control, the BHP is dependent on the rates,
// the well rates is also dependent on the BHP, so it might need to do some iteration.
// However, when group control is involved, change of the rates might impacts other wells
// so iterations on a higher level will be required. Some investigation might be needed when
// we face problems under THP control.
assert(int(rates.size()) == 3); // the vfp related only supports three phases now.
static constexpr int Gas = BlackoilPhases::Vapour;
static constexpr int Oil = BlackoilPhases::Liquid;
static constexpr int Water = BlackoilPhases::Aqua;
const EvalWell aqua = rates[Water];
const EvalWell liquid = rates[Oil];
const EvalWell vapour = rates[Gas];
const Scalar thp_limit = well_.getTHPConstraint(summaryState);
Scalar vfp_ref_depth;
EvalWell bhp_tab;
if (well_.isInjector() )
{
const auto& controls = well.injectionControls(summaryState);
vfp_ref_depth = well_.vfpProperties()->getInj()->getTable(controls.vfp_table_number).getDatumDepth();
bhp_tab = well_.vfpProperties()->getInj()->bhp(
controls.vfp_table_number, aqua, liquid, vapour, thp_limit);
}
else if (well_.isProducer()) {
const auto& controls = well.productionControls(summaryState);
vfp_ref_depth = well_.vfpProperties()->getProd()->getTable(controls.vfp_table_number).getDatumDepth();
const auto& wfr = well_.vfpProperties()->getExplicitWFR(controls.vfp_table_number, well_.indexOfWell());
const auto& gfr = well_.vfpProperties()->getExplicitGFR(controls.vfp_table_number, well_.indexOfWell());
const bool use_vfpexplicit = well_.useVfpExplicit();
bhp_tab = well_.vfpProperties()->getProd()->bhp(controls.vfp_table_number,
aqua, liquid, vapour,
thp_limit,
well_.getALQ(well_state),
wfr, gfr, use_vfpexplicit);
}
else {
OPM_DEFLOG_THROW(std::logic_error, "Expected INJECTOR or PRODUCER for well " + well_.name(), deferred_logger);
}
Scalar bhp_tab_double_value;
if constexpr (std::is_same_v<EvalWell, Scalar>) {
bhp_tab_double_value = bhp_tab;
}
else { // EvalWell and bhp_tab is of type DenseAd::Evaluation<double,...,...>
bhp_tab_double_value = bhp_tab.value();
}
const auto bhp_adjustment = getVfpBhpAdjustment(bhp_tab_double_value, thp_limit);
const Scalar dp_hydro = wellhelpers::computeHydrostaticCorrection(well_.refDepth(),
vfp_ref_depth,
rho,
well_.gravity());
return bhp_tab - dp_hydro + bhp_adjustment;
}
template<class Scalar>
Scalar WellBhpThpCalculator<Scalar>::
calculateMinimumBhpFromThp(const WellState<Scalar>& well_state,
const Well& well,
const SummaryState& summaryState,
const Scalar rho) const
{
assert(well_.isProducer()); // only producers can go here for now
const Scalar thp_limit = well_.getTHPConstraint(summaryState);
const auto& controls = well.productionControls(summaryState);
const auto& wfr = well_.vfpProperties()->getExplicitWFR(controls.vfp_table_number, well_.indexOfWell());
const auto& gfr = well_.vfpProperties()->getExplicitGFR(controls.vfp_table_number, well_.indexOfWell());
const Scalar bhp_min = well_.vfpProperties()->getProd()->minimumBHP(controls.vfp_table_number,
thp_limit, wfr, gfr,
well_.getALQ(well_state));
const Scalar vfp_ref_depth = well_.vfpProperties()->getProd()->getTable(controls.vfp_table_number).getDatumDepth();
const auto bhp_adjustment = getVfpBhpAdjustment(bhp_min, thp_limit);
const Scalar dp_hydro = wellhelpers::computeHydrostaticCorrection(well_.refDepth(), vfp_ref_depth,
rho, well_.gravity());
return bhp_min - dp_hydro + bhp_adjustment;
}
template<class Scalar>
Scalar WellBhpThpCalculator<Scalar>::
getVfpBhpAdjustment(const Scalar bhp_tab, const Scalar thp_limit) const
{
return well_.wellEcl().getWVFPDP().getPressureLoss(bhp_tab, thp_limit);
}
template<class Scalar>
template<class ErrorPolicy>
std::optional<Scalar>
WellBhpThpCalculator<Scalar>::
computeBhpAtThpLimitInjImpl(const std::function<std::vector<Scalar>(const Scalar)>& frates,
const SummaryState& summary_state,
const Scalar rho,
const Scalar flo_rel_tol,
const int max_iteration,
DeferredLogger& deferred_logger) const
{
// Given a VFP function returning bhp as a function of phase
// rates and thp:
// fbhp(rates, thp),
// a function extracting the particular flow rate used for VFP
// lookups:
// flo(rates)
// and the inflow function (assuming the reservoir is fixed):
// frates(bhp)
// we want to solve the equation:
// fbhp(frates(bhp, thplimit)) - bhp = 0
// for bhp.
//
// This may result in 0, 1 or 2 solutions. If two solutions,
// the one corresponding to the lowest bhp (and therefore
// highest rate) is returned.
//
// In order to detect these situations, we will find piecewise
// linear approximations both to the inverse of the frates
// function and to the fbhp function.
//
// We first take the FLO sample points of the VFP curve, and
// find the corresponding bhp values by solving the equation:
// flo(frates(bhp)) - flo_sample = 0
// for bhp, for each flo_sample. The resulting (flo_sample,
// bhp_sample) values give a piecewise linear approximation to
// the true inverse inflow function, at the same flo values as
// the VFP data.
//
// Then we extract a piecewise linear approximation from the
// multilinear fbhp() by evaluating it at the flo_sample
// points, with fractions given by the frates(bhp_sample)
// values.
//
// When we have both piecewise linear curves defined on the
// same flo_sample points, it is easy to distinguish between
// the 0, 1 or 2 solution cases, and obtain the right interval
// in which to solve for the solution we want (with highest
// flow in case of 2 solutions).
static constexpr int Water = BlackoilPhases::Aqua;
static constexpr int Oil = BlackoilPhases::Liquid;
static constexpr int Gas = BlackoilPhases::Vapour;
// Make the fbhp() function.
const auto& controls = well_.wellEcl().injectionControls(summary_state);
const auto& table = well_.vfpProperties()->getInj()->getTable(controls.vfp_table_number);
const Scalar vfp_ref_depth = table.getDatumDepth();
const Scalar thp_limit = this->getTHPConstraint(summary_state);
const Scalar dp = wellhelpers::computeHydrostaticCorrection(well_.refDepth(),
vfp_ref_depth,
rho, well_.gravity());
auto fbhp = [this, &controls, thp_limit, dp](const std::vector<Scalar>& rates) {
assert(rates.size() == 3);
const auto bhp = well_.vfpProperties()->getInj()
->bhp(controls.vfp_table_number, rates[Water], rates[Oil], rates[Gas], thp_limit);
return bhp - dp + getVfpBhpAdjustment(bhp, thp_limit);
};
// Make the flo() function.
auto flo = [&table](const std::vector<Scalar>& rates) {
return detail::getFlo(table, rates[Water], rates[Oil], rates[Gas]);
};
// Get the flo samples, add extra samples at low rates and bhp
// limit point if necessary.
std::vector<double> flo_samples = table.getFloAxis();
if (flo_samples[0] > 0.0) {
const double f0 = flo_samples[0];
flo_samples.insert(flo_samples.begin(), { f0/20.0, f0/10.0, f0/5.0, f0/2.0 });
}
const Scalar flo_bhp_limit = flo(frates(controls.bhp_limit));
if (flo_samples.back() < flo_bhp_limit) {
flo_samples.push_back(flo_bhp_limit);
}
// Find bhp values for inflow relation corresponding to flo samples.
std::vector<Scalar> bhp_samples;
for (Scalar flo_sample : flo_samples) {
if (flo_sample > flo_bhp_limit) {
// We would have to go over the bhp limit to obtain a
// flow of this magnitude. We associate all such flows
// with simply the bhp limit. The first one
// encountered is considered valid, the rest not. They
// are therefore skipped.
bhp_samples.push_back(controls.bhp_limit);
break;
}
auto eq = [&flo, &frates, flo_sample](Scalar bhp) {
return flo(frates(bhp)) - flo_sample;
};
// TODO: replace hardcoded low/high limits.
const Scalar low = 10.0 * unit::barsa;
const Scalar high = 800.0 * unit::barsa;
const Scalar flo_tolerance = flo_rel_tol * std::fabs(flo_samples.back());
int iteration = 0;
try {
const Scalar solved_bhp = RegulaFalsiBisection<ErrorPolicy>::
solve(eq, low, high, max_iteration, flo_tolerance, iteration);
bhp_samples.push_back(solved_bhp);
}
catch (...) {
// Use previous value (or max value if at start) if we failed.
bhp_samples.push_back(bhp_samples.empty() ? low : bhp_samples.back());
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE_EXTRACT_SAMPLES",
"Robust bhp(thp) solve failed extracting bhp values at flo samples for well " + well_.name());
}
}
// Find bhp values for VFP relation corresponding to flo samples.
const int num_samples = bhp_samples.size(); // Note that this can be smaller than flo_samples.size()
std::vector<Scalar> fbhp_samples(num_samples);
for (int ii = 0; ii < num_samples; ++ii) {
fbhp_samples[ii] = fbhp(frates(bhp_samples[ii]));
}
if constexpr (extraBhpAtThpLimitOutput) {
std::string dbgmsg;
dbgmsg += "flo: ";
for (int ii = 0; ii < num_samples; ++ii) {
dbgmsg += " " + std::to_string(flo_samples[ii]);
}
dbgmsg += "\nbhp: ";
for (int ii = 0; ii < num_samples; ++ii) {
dbgmsg += " " + std::to_string(bhp_samples[ii]);
}
dbgmsg += "\nfbhp: ";
for (int ii = 0; ii < num_samples; ++ii) {
dbgmsg += " " + std::to_string(fbhp_samples[ii]);
}
OpmLog::debug(dbgmsg);
}
// Look for sign changes for the (fbhp_samples - bhp_samples) piecewise linear curve.
// We only look at the valid
int sign_change_index = -1;
for (int ii = 0; ii < num_samples - 1; ++ii) {
const Scalar curr = fbhp_samples[ii] - bhp_samples[ii];
const Scalar next = fbhp_samples[ii + 1] - bhp_samples[ii + 1];
if (curr * next < 0.0) {
// Sign change in the [ii, ii + 1] interval.
sign_change_index = ii; // May overwrite, thereby choosing the highest-flo solution.
}
}
// Handle the no solution case.
if (sign_change_index == -1) {
return std::nullopt;
}
// Solve for the proper solution in the given interval.
auto eq = [&fbhp, &frates](Scalar bhp) {
return fbhp(frates(bhp)) - bhp;
};
// TODO: replace hardcoded low/high limits.
const Scalar low = bhp_samples[sign_change_index + 1];
const Scalar high = bhp_samples[sign_change_index];
const Scalar bhp_tolerance = 0.01 * unit::barsa;
int iteration = 0;
if (low == high) {
// We are in the high flow regime where the bhp_samples
// are all equal to the bhp_limit.
assert(low == controls.bhp_limit);
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE",
"Robust bhp(thp) solve failed for well " + well_.name());
return std::nullopt;
}
try {
const Scalar solved_bhp = RegulaFalsiBisection<ErrorPolicy>::
solve(eq, low, high, max_iteration, bhp_tolerance, iteration);
if constexpr (extraBhpAtThpLimitOutput) {
OpmLog::debug("***** " + well_.name() + " solved_bhp = " + std::to_string(solved_bhp)
+ " flo_bhp_limit = " + std::to_string(flo_bhp_limit));
}
return solved_bhp;
}
catch (...) {
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE",
"Robust bhp(thp) solve failed for well " + well_.name());
return std::nullopt;
}
}
template<class Scalar>
std::optional<Scalar>
WellBhpThpCalculator<Scalar>::
bhpMax(const std::function<Scalar(const Scalar)>& fflo,
const Scalar bhp_limit,
const Scalar maxPerfPress,
const Scalar vfp_flo_front,
DeferredLogger& deferred_logger) const
{
// Find the bhp-point where production becomes nonzero.
Scalar bhp_max = 0.0;
Scalar low = bhp_limit;
Scalar high = maxPerfPress + 1.0 * unit::barsa;
Scalar f_low = fflo(low);
Scalar f_high = fflo(high);
if constexpr (extraBhpAtThpLimitOutput) {
deferred_logger.debug("computeBhpAtThpLimitProd(): well = " + well_.name() +
" low = " + std::to_string(low) +
" high = " + std::to_string(high) +
" f(low) = " + std::to_string(f_low) +
" f(high) = " + std::to_string(f_high));
}
int adjustments = 0;
const int max_adjustments = 10;
const Scalar adjust_amount = 5.0 * unit::barsa;
while (f_low * f_high > 0.0 && adjustments < max_adjustments) {
// Same sign, adjust high to see if we can flip it.
high += adjust_amount;
f_high = fflo(high);
++adjustments;
}
if (f_low * f_high > 0.0) {
if (f_low > 0.0) {
// Even at the BHP limit, we are injecting.
// There will be no solution here, return an
// empty optional.
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE_INOPERABLE",
"Robust bhp(thp) solve failed due to inoperability for well " + well_.name());
return std::nullopt;
} else {
// Still producing, even at high bhp.
assert(f_high < 0.0);
bhp_max = high;
}
} else {
// Bisect to find a bhp point where we produce, but
// not a large amount ('eps' below).
const Scalar eps = 0.1 * std::fabs(vfp_flo_front);
const int maxit = 50;
int it = 0;
while (std::fabs(f_low) > eps && it < maxit) {
const Scalar curr = 0.5*(low + high);
const Scalar f_curr = fflo(curr);
if (f_curr * f_low > 0.0) {
low = curr;
f_low = f_curr;
} else {
high = curr;
f_high = f_curr;
}
++it;
}
if (it < maxit) {
bhp_max = low;
} else {
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE_INOPERABLE",
"Bisect did not find the bhp-point where we produce for well " + well_.name());
return std::nullopt;
}
}
if constexpr (extraBhpAtThpLimitOutput) {
deferred_logger.debug("computeBhpAtThpLimitProd(): well = " + well_.name() +
" low = " + std::to_string(low) +
" high = " + std::to_string(high) +
" f(low) = " + std::to_string(f_low) +
" f(high) = " + std::to_string(f_high) +
" bhp_max = " + std::to_string(bhp_max));
}
return bhp_max;
}
template<class Scalar>
std::optional<Scalar>
WellBhpThpCalculator<Scalar>::
computeBhpAtThpLimit(const std::function<std::vector<Scalar>(const Scalar)>& frates,
const std::function<Scalar(const std::vector<Scalar>)>& fbhp,
const std::array<Scalar, 2>& range,
DeferredLogger& deferred_logger) const
{
// Given a VFP function returning bhp as a function of phase
// rates and thp:
// fbhp(rates, thp),
// a function extracting the particular flow rate used for VFP
// lookups:
// flo(rates)
// and the inflow function (assuming the reservoir is fixed):
// frates(bhp)
// we want to solve the equation:
// fbhp(frates(bhp, thplimit)) - bhp = 0
// for bhp.
//
// This may result in 0, 1 or 2 solutions. If two solutions,
// the one corresponding to the lowest bhp (and therefore
// highest rate) should be returned.
// Define the equation we want to solve.
auto eq = [&fbhp, &frates](Scalar bhp) {
return fbhp(frates(bhp)) - bhp;
};
// Find appropriate brackets for the solution.
std::optional<Scalar> approximate_solution;
Scalar low, high;
// trying to use bisect way to locate a bracket
bool finding_bracket = this->bisectBracket(eq, range, low, high,
approximate_solution, deferred_logger);
// based on the origional design, if an approximate solution is suggested, we use this value directly
// in the long run, we might change it
if (approximate_solution.has_value()) {
return *approximate_solution;
}
if (!finding_bracket) {
deferred_logger.debug(" Trying the brute force search to bracket the bhp for last attempt ");
finding_bracket = this->bruteForceBracket(eq, range, low, high, deferred_logger);
}
if (!finding_bracket) {
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE_INOPERABLE",
"Robust bhp(thp) solve failed due to not being able to "
"bracket the bhp solution with the brute force search for " + well_.name());
return std::nullopt;
}
// Solve for the proper solution in the given interval.
const int max_iteration = 100;
const Scalar bhp_tolerance = 0.01 * unit::barsa;
int iteration = 0;
try {
const Scalar solved_bhp = RegulaFalsiBisection<ThrowOnError>::
solve(eq, low, high, max_iteration, bhp_tolerance, iteration);
return solved_bhp;
}
catch (...) {
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE",
"Robust bhp(thp) solve failed for well " + well_.name());
return std::nullopt;
}
}
template<class Scalar>
bool WellBhpThpCalculator<Scalar>::
bisectBracket(const std::function<Scalar(const Scalar)>& eq,
const std::array<Scalar, 2>& range,
Scalar& low, Scalar& high,
std::optional<Scalar>& approximate_solution,
DeferredLogger& deferred_logger) const
{
bool finding_bracket = false;
low = range[0];
high = range[1];
Scalar eq_high = eq(high);
Scalar eq_low = eq(low);
const Scalar eq_bhplimit = eq_low;
if constexpr (extraBhpAtThpLimitOutput) {
deferred_logger.debug("computeBhpAtThpLimitProd(): well = " + well_.name() +
" low = " + std::to_string(low) +
" high = " + std::to_string(high) +
" eq(low) = " + std::to_string(eq_low) +
" eq(high) = " + std::to_string(eq_high));
}
if (eq_low * eq_high > 0.0) {
// Failed to bracket the zero.
// If this is due to having two solutions, bisect until bracketed.
Scalar abs_low = std::fabs(eq_low);
Scalar abs_high = std::fabs(eq_high);
int bracket_attempts = 0;
const int max_bracket_attempts = 20;
Scalar interval = high - low;
const Scalar min_interval = 1.0 * unit::barsa;
while (eq_low * eq_high > 0.0 && bracket_attempts < max_bracket_attempts && interval > min_interval) {
if (abs_high < abs_low) {
low = 0.5 * (low + high);
eq_low = eq(low);
abs_low = std::fabs(eq_low);
} else {
high = 0.5 * (low + high);
eq_high = eq(high);
abs_high = std::fabs(eq_high);
}
interval = high - low;
++bracket_attempts;
}
if (eq_low * eq_high <= 0.) {
// We have a bracket!
finding_bracket = true;
// Now, see if (bhplimit, low) is a bracket in addition to (low, high).
// If so, that is the bracket we shall use, choosing the solution with the
// highest flow.
if (eq_low * eq_bhplimit <= 0.0) {
high = low;
low = range[0];
}
} else { // eq_low * eq_high > 0.0
// Still failed bracketing!
const Scalar limit = 0.1 * unit::barsa;
if (std::min(abs_low, abs_high) < limit) {
// Return the least bad solution if less off than 0.1 bar.
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE_BRACKETING_FAILURE",
"Robust bhp(thp) not solved precisely for well " + well_.name());
approximate_solution = abs_low < abs_high ? low : high;
} else {
// Return failure.
deferred_logger.warning("FAILED_ROBUST_BHP_THP_SOLVE_BRACKETING_FAILURE",
"Robust bhp(thp) solve failed due to bracketing failure for well " +
well_.name());
}
}
} else {
finding_bracket = true;
}
return finding_bracket;
}
template<class Scalar>
bool WellBhpThpCalculator<Scalar>::
bruteForceBracket(const std::function<Scalar(const Scalar)>& eq,
const std::array<Scalar, 2>& range,
Scalar& low, Scalar& high,
DeferredLogger& deferred_logger)
{
bool bracket_found = false;
low = range[0];
high = range[1];
const int sample_number = 200;
const Scalar interval = (high - low) / sample_number;
Scalar eq_low = eq(low);
Scalar eq_high = 0.0;
for (int i = 0; i < sample_number + 1; ++i) {
high = range[0] + interval * i;
eq_high = eq(high);
if (eq_high * eq_low <= 0.) {
bracket_found = true;
break;
}
low = high;
eq_low = eq_high;
}
if (bracket_found) {
deferred_logger.debug(
" brute force solve found low " + std::to_string(low) + " with eq_low " + std::to_string(eq_low) +
" high " + std::to_string(high) + " with eq_high " + std::to_string(eq_high));
}
return bracket_found;
}
template<class Scalar>
bool WellBhpThpCalculator<Scalar>::
isStableSolution(const WellState<Scalar>& well_state,
const Well& well,
const std::vector<Scalar>& rates,
const SummaryState& summaryState) const
{
assert(int(rates.size()) == 3); // the vfp related only supports three phases now.
assert(well_.isProducer()); // only valid for producers
static constexpr int Gas = BlackoilPhases::Vapour;
static constexpr int Oil = BlackoilPhases::Liquid;
static constexpr int Water = BlackoilPhases::Aqua;
const Scalar aqua = rates[Water];
const Scalar liquid = rates[Oil];
const Scalar vapour = rates[Gas];
const Scalar thp = well_.getTHPConstraint(summaryState);
const auto& controls = well.productionControls(summaryState);
const auto& wfr = well_.vfpProperties()->getExplicitWFR(controls.vfp_table_number, well_.indexOfWell());
const auto& gfr = well_.vfpProperties()->getExplicitGFR(controls.vfp_table_number, well_.indexOfWell());
const auto& table = well_.vfpProperties()->getProd()->getTable(controls.vfp_table_number);
const bool use_vfpexplicit = well_.useVfpExplicit();
auto bhp = VFPHelpers<double>::bhp(table, aqua, liquid, vapour, thp,
well_.getALQ(well_state), wfr, gfr,
use_vfpexplicit);
if (bhp.dflo >= 0) {
return true;
} else { // maybe check if ipr is available
const auto ipr = getFloIPR(well_state, well, summaryState);
return bhp.dflo + 1.0 / ipr.second >= 0;
}
}
template<class Scalar>
std::optional<Scalar> WellBhpThpCalculator<Scalar>::
estimateStableBhp(const WellState<Scalar>& well_state,
const Well& well,
const std::vector<Scalar>& rates,
const Scalar rho,
const SummaryState& summaryState) const
{
// Given a *converged* well_state with ipr, estimate bhp of the stable solution
const auto& controls = well.productionControls(summaryState);
const Scalar thp = well_.getTHPConstraint(summaryState);
const auto& table = well_.vfpProperties()->getProd()->getTable(controls.vfp_table_number);
const Scalar aqua = rates[BlackoilPhases::Aqua];
const Scalar liquid = rates[BlackoilPhases::Liquid];
const Scalar vapour = rates[BlackoilPhases::Vapour];
Scalar flo = detail::getFlo(table, aqua, liquid, vapour);
Scalar wfr, gfr;
if (well_.useVfpExplicit() || -flo < table.getFloAxis().front()) {
wfr = well_.vfpProperties()->getExplicitWFR(controls.vfp_table_number, well_.indexOfWell());
gfr = well_.vfpProperties()->getExplicitGFR(controls.vfp_table_number, well_.indexOfWell());
} else {
wfr = detail::getWFR(table, aqua, liquid, vapour);
gfr = detail::getGFR(table, aqua, liquid, vapour);
}
auto ipr = getFloIPR(well_state, well, summaryState);
const Scalar vfp_ref_depth = well_.vfpProperties()->getProd()->getTable(controls.vfp_table_number).getDatumDepth();
const Scalar dp_hydro = wellhelpers::computeHydrostaticCorrection(well_.refDepth(), vfp_ref_depth,
rho, well_.gravity());
auto bhp_adjusted = [this, &thp, &dp_hydro](const Scalar bhp) {
return bhp - dp_hydro + getVfpBhpAdjustment(bhp, thp);
};
const auto retval = VFPHelpers<double>::intersectWithIPR(table, thp, wfr, gfr,
well_.getALQ(well_state),
ipr.first, ipr.second,
bhp_adjusted);
if (retval.has_value()) {
// returned pair is (flo, bhp)
return retval.value().second;
} else {
return std::nullopt;
}
}
template<class Scalar>
std::pair<Scalar, Scalar> WellBhpThpCalculator<Scalar>::
getFloIPR(const WellState<Scalar>& well_state,
const Well& well,
const SummaryState& summary_state) const
{
// Convert ipr_a's and ipr_b's to our particular choice of FLO
const auto& controls = well.productionControls(summary_state);
const auto& table = well_.vfpProperties()->getProd()->getTable(controls.vfp_table_number);
const auto& pu = well_.phaseUsage();
const auto& ipr_a = well_state.well(well_.indexOfWell()).implicit_ipr_a;
const Scalar& aqua_a = pu.phase_used[BlackoilPhases::Aqua]? ipr_a[pu.phase_pos[BlackoilPhases::Aqua]] : 0.0;
const Scalar& liquid_a = pu.phase_used[BlackoilPhases::Liquid]? ipr_a[pu.phase_pos[BlackoilPhases::Liquid]] : 0.0;
const Scalar& vapour_a = pu.phase_used[BlackoilPhases::Vapour]? ipr_a[pu.phase_pos[BlackoilPhases::Vapour]] : 0.0;
const auto& ipr_b = well_state.well(well_.indexOfWell()).implicit_ipr_b;
const Scalar& aqua_b = pu.phase_used[BlackoilPhases::Aqua]? ipr_b[pu.phase_pos[BlackoilPhases::Aqua]] : 0.0;
const Scalar& liquid_b = pu.phase_used[BlackoilPhases::Liquid]? ipr_b[pu.phase_pos[BlackoilPhases::Liquid]] : 0.0;
const Scalar& vapour_b = pu.phase_used[BlackoilPhases::Vapour]? ipr_b[pu.phase_pos[BlackoilPhases::Vapour]] : 0.0;
// The getFlo helper is indended to pick one or add two of the phase rates (depending on FLO-type),
// but we can equally use it to pick/add the corresponding ipr_a, ipr_b
return std::make_pair(detail::getFlo(table, aqua_a, liquid_a, vapour_a),
detail::getFlo(table, aqua_b, liquid_b, vapour_b));
}
template<class Scalar>
bool
WellBhpThpCalculator<Scalar>::
bruteForceBracketCommonTHP(const std::function<Scalar(const Scalar)>& eq,
const std::array<Scalar, 2>& range,
Scalar& low, Scalar& high,
std::optional<Scalar>& approximate_solution,
const Scalar& limit,
DeferredLogger& deferred_logger)
{
bool bracket_found = false;
low = range[0];
high = range[1];
const int sample_number = 300;
const Scalar interval = (high - low) / sample_number;
Scalar eq_low = eq(low);
Scalar eq_high = 0.0;
for (int i = 0; i < sample_number + 1; ++i) {
high = range[0] + interval * i;
eq_high = eq(high);
if ( (std::fabs(eq_high) < limit)) {
approximate_solution = high;
break;
}
if (eq_high * eq_low <= 0.) {
bracket_found = true;
break;
}
low = high;
eq_low = eq_high;
}
if (bracket_found) {
deferred_logger.debug(
" brute force solve found low " + std::to_string(low) + " with eq_low " + std::to_string(eq_low) +
" high " + std::to_string(high) + " with eq_high " + std::to_string(eq_high));
}
return bracket_found;
}
template<class Scalar>
bool
WellBhpThpCalculator<Scalar>::
bruteForceBracketCommonTHP(const std::function<Scalar(const Scalar)>& eq,
Scalar& min_thp, Scalar& max_thp)
{
bool bracket_found = false;
constexpr int sample_number = 1000;
constexpr Scalar interval = 1E5;
Scalar eq_low = eq(min_thp);
Scalar eq_high = 0.0;
for (int i = 0; i < sample_number + 1; ++i) {
max_thp = min_thp + interval * i;
eq_high = eq(max_thp);
if (eq_high * eq_low <= 0.) {
bracket_found = true;
min_thp = max_thp - interval;
break;
}
eq_low = eq_high;
}
return bracket_found;
}
template class WellBhpThpCalculator<double>;
#define INSTANCE(...) \
template __VA_ARGS__ WellBhpThpCalculator<double>:: \
calculateBhpFromThp<__VA_ARGS__>(const WellState<double>&, \
const std::vector<__VA_ARGS__>&, \
const Well&, \
const SummaryState&, \
const double, \
DeferredLogger&) const;
INSTANCE(double)
INSTANCE(DenseAd::Evaluation<double,3,0u>)
INSTANCE(DenseAd::Evaluation<double,4,0u>)
INSTANCE(DenseAd::Evaluation<double,5,0u>)
INSTANCE(DenseAd::Evaluation<double,6,0u>)
INSTANCE(DenseAd::Evaluation<double,7,0u>)
INSTANCE(DenseAd::Evaluation<double,8,0u>)
INSTANCE(DenseAd::Evaluation<double,9,0u>)
INSTANCE(DenseAd::Evaluation<double,10,0u>)
INSTANCE(DenseAd::Evaluation<double,-1,4u>)
INSTANCE(DenseAd::Evaluation<double,-1,5u>)
INSTANCE(DenseAd::Evaluation<double,-1,6u>)
INSTANCE(DenseAd::Evaluation<double,-1,7u>)
INSTANCE(DenseAd::Evaluation<double,-1,8u>)
INSTANCE(DenseAd::Evaluation<double,-1,9u>)
INSTANCE(DenseAd::Evaluation<double,-1,10u>)
INSTANCE(DenseAd::Evaluation<double,-1,11u>)
} // namespace Opm
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