From 3bed5f41c1275cf1bf386ba0cbef7834a801af80 Mon Sep 17 00:00:00 2001
From: Kai Bao <kai.bao@sintef.no>
Date: Fri, 23 Sep 2022 09:37:32 +0200
Subject: [PATCH] for the cells having zero thickness

we use the cell center depth to do the equilibration
---
 ebos/equil/initstateequil.cc | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/ebos/equil/initstateequil.cc b/ebos/equil/initstateequil.cc
index 6d2701f26..adc7bf058 100644
--- a/ebos/equil/initstateequil.cc
+++ b/ebos/equil/initstateequil.cc
@@ -1864,8 +1864,18 @@ equilibrateHorizontal(const CellRange&  cells,
             totfrac += frac;
         }
 
-        saturations /= totfrac;
-        pressures   /= totfrac;
+        if (totfrac > 0.) {
+            saturations /= totfrac;
+            pressures /= totfrac;
+        } else {
+            // Fall back to centre point method for zero-thickness cells.
+            const auto pos = CellPos {
+                    cell, cellCenterDepth_[cell]
+            };
+
+            saturations = psat.deriveSaturations(pos, eqreg, ptable);
+            pressures   = psat.correctedPhasePressures();
+        }
 
         const auto temp = this->temperature_[cell];
         const auto cz   = cellCenterDepth_[cell];