From 00f7f8a7a05b64caee62e8bb22d6ef217db54259 Mon Sep 17 00:00:00 2001
From: Vegard Kippe <vkip@equinor.com>
Date: Tue, 1 Sep 2026 09:34:34 +0200
Subject: [PATCH] Ensure GUIDRAT is checked when WGRUPCON value is defaulted +
 add utility function to get potential.

---
 .../eclipse/Schedule/Group/GuideRate.cpp      | 22 ++++++++++++++++++-
 .../eclipse/Schedule/Group/GuideRate.hpp      |  8 +++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/opm/input/eclipse/Schedule/Group/GuideRate.cpp b/opm/input/eclipse/Schedule/Group/GuideRate.cpp
index d5c999ac54d..eef2e0b0429 100644
--- a/opm/input/eclipse/Schedule/Group/GuideRate.cpp
+++ b/opm/input/eclipse/Schedule/Group/GuideRate.cpp
@@ -133,6 +133,24 @@ double Opm::GuideRate::get(const std::string& name, const Phase& phase) const
     return iter->second;
 }
 
+double Opm::GuideRate::getPotential(const std::string&           name,
+                                    const GuideRateModel::Target model_target) const
+{
+    if ((model_target == GuideRateModel::Target::NONE) ||
+        (model_target == GuideRateModel::Target::COMB))
+    {
+        // No potential can be associated with these targets.
+        return 0.0;
+    }
+
+    auto pot = this->potentials.find(name);
+    if (pot == this->potentials.end()) {
+        return 0.0;
+    }
+
+    return pot->second.eval(model_target);
+}
+
 double Opm::GuideRate::getSI(const std::string&          well,
                              const Well::GuideRateTarget target,
                              const RateVector&           rates) const
@@ -340,9 +358,11 @@ void Opm::GuideRate::well_compute(const std::string& wgname,
 
             const auto& model = config.has_model() ? config.model() : GuideRateModel{};
             this->assign_grvalue(wgname, model, { sim_time, well.guide_rate, model_target });
+            return;
         }
     }
-    else if (config.has_model()) { // GUIDERAT
+    // A well can have WGRUPCON with defaulted guide rate, in which case we must check for GUIDRAT
+    if (config.has_model()) { // GUIDERAT
         if (! this->schedule.hasWell(wgname, report_step)) {
             // 'wgname' might be a group or the well is not yet online.
             return;
diff --git a/opm/input/eclipse/Schedule/Group/GuideRate.hpp b/opm/input/eclipse/Schedule/Group/GuideRate.hpp
index 156000c0a66..b2f33b9f2cc 100644
--- a/opm/input/eclipse/Schedule/Group/GuideRate.hpp
+++ b/opm/input/eclipse/Schedule/Group/GuideRate.hpp
@@ -145,6 +145,14 @@ class GuideRate
     double get(const std::string& name, const GuideRateModel::Target model_target, const RateVector& rates) const;
     double get(const std::string& group, const Phase& phase) const;
 
+    /// \brief Guide rate of a well or group based on its potentials alone.
+    ///
+    /// This is the value that get() returns when no GUIDERAT/WGRUPCON guide
+    /// rate has been computed for 'name'.  Callers that need the "default"
+    /// (potential based) guide rate irrespective of whether GUIDERAT is
+    /// active use this accessor.  Returns 0.0 if no potentials are stored.
+    double getPotential(const std::string& name, const GuideRateModel::Target model_target) const;
+
     double getSI(const std::string& well, const WellGuideRateTarget target, const RateVector& rates) const;
     double getSI(const std::string& group, const Group::GuideRateProdTarget target, const RateVector& rates) const;
     double getSI(const std::string& wgname, const GuideRateModel::Target target, const RateVector& rates) const;