How to find field candidates for enhanced recovery by water additives on the NCS Enhanced Recovery by water additives FORCE Seminar 8. 2. 27 Jan Bygdevoll, Principal Engineer, NPD
Why is a field a candidate for enhanced recovery? Because there is more oil to potentially be recovered than by methods applied today What is a method for enhanced recovery? Anything that increase (or enhance) the recovery of oil (or gas) from a field Injection methods Water Gas, including CO 2 Combination (WAG) Additives to injected water Surfactants Polymers Other? 8.2.7 2
Norwegian Oil production RNB26 Oljeproduksjon, Norsk kontinentalsokkel Alle ressurskategorier 2 18 16 14 12 Uoppdagede ressurser Ressurser i funn Ressurser i felt Reserver Faktisk Produsert per 31.12.25: 3, GSm3 Gjenværende reserver: 1,2 GSm3 Ressurser i felt:,4 GSm3 Ressurser i funn:,1 GSm3 Uoppdagede ressurser: 1,2 GSm3 MSm3 1 8 6 4 2 197 198 199 2 21 22 23 M:\Lag\D-RessAnalyse\EKM\Totalprod.xls 8.2.7 3
Oil production prognosis to 211 (RNB 27) 2 Ressurser i funn/resources in discoveries Ressurser i felt/resources in fields Reserver/Reserves Historisk produksjon/actual production 3. 15 millioner Sm³ million Sm 3 1 2. millioner fat per dag million barrels per day 5 1. 1995 1997 1999 21 23 25 27 29 211. 8.2.7 4
Oil profiles for Norwegian fields 2 18 16 Rest 14 Balder 12 Norne Ula MSm3 1 Draugen 8 6 Oseberg Heidrun Troll Grane Grane 4 Gullfaks Snorre Valhall Eldfisk 2 Statfjord Ekofisk 198 1985 199 1995 2 25 21 215 22 225 8.2.7 5
Status for NPD s goal on Reserve Growth for Oil 25 215 8 Goal for reserve growth 7 6 Prognosis autumn 24 for reserve growth total Prognosis autumn 24 for reserve growth in existing fields Cumulative reserve growth in total Cumulative reserve growth from existing fields 5 Mill Sm3 4 3 2 1 24 25 26 27 28 29 21 211 212 213 214 8.2.7 6
Status for NPD s goal on Reserve Growth for Oil 25 215 8 7 Goal for reserve growth Prognosis autumn 24 for reserve growth total Prognosis autumn 24 for reserve growth in existing fields Cumulative reserve growth in total Cumulative reserve growth from existing fields RNB 26 Operators prognosis RNB 27 Operators prognosis 6 5 Mill Sm3 4 3 2 1 24 25 26 27 28 29 21 211 212 213 214 8.2.7 7
6 4 2-2 -4-6 Produced, yet to produce and oil remaining in ground based on current plans Ekofisk Troll II Eldfisk Valhall Snorre Heidrun Statfjord Oseberg Gullfaks Troll I Oseberg Sør Tor Gullfaks Sør Njord Grane Vest Ekofisk Brage Balder Kristin Ula Draugen Snøhvit Oseberg Øst Norne Visund Veslefrikk Vigdis Alvheim Gyda Tordis Åsgard Hod Remaining oil in ground at planned cessation Produced oil end 26 Remaining oil reserves 8.2.7 8 MSm³
Produced, yet to produce and oil remaining in ground based on current plans 6 4 2 MSm³ -2 Chalk reservoir Sand reservoir w/ water inj Sand reservoir w/ gas inj -4 Remaining oil in ground at planned cessation Produced oil end 26 Remaining oil reserves -6 8.2.7 9
12 1 8 6 4 2-2 -4-6 -8-1 Produced, yet to produce and oil remaining in ground based on current plans Snøhvit Oseberg Øst Norne Visund Veslefrikk Vigdis Alvheim Gyda Tordis Åsgard Hod Fram Statfjord Nord Embla Frøy Albuskjell Statfjord Øst Kvitebjørn Varg Yme Tyrihans Jotun Glitne Tambar Mime Urd Volve Remaining oil in ground at planned cessation Produced oil end 26 Remaining oil reserves 8.2.7 1 MSm³
Development in recovery factor grouped by field seize 6 Recovery Factor Oil (%) 5 4 3 2 NB! The number of fields varies with time 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 <15 million Sm3 oil > 5 million Sm3 oil 15-5 million Sm3 oil Average all fields 8.2.7 11
Recovery factor versus Reservoir Complexity Index (RCI) a tool for estimating potential?.7 y = -.776x +.7779 R 2 =.895.6.5 Utv grad.4.3.2.1..1.2.3.4.5.6.7.8.9 8.2.7 RCI 12
Reservoir Complexity Index (RCI) parameters used in evaluation Complexity attribute Description Low complexity 1 2 Complexity score 3 4 High complexity 5 Average permeability Describes the pore volume weighted average permeability in the main flow direction of the defined reservoir. md > 1. 1-1 1-1 1-1 < 1 Permeability contrast Describes the permeability contrast between geological layers/facies types, and is calculated as log1[kmax/kmin] <1 1-2 2-3 3-4 >4 Structural complexity Describes how fluid flow between wells is affected by fault density, fault throw, fault transmissibility,. The fault properties does not restrict fluid flow. The fault properties restrict fluid flow significantly. (High density of faults with throw larger than reservoir thickness and/or 'zero' transmissibility). Lateral stratigraphic continuity Describes the stratigraphic continuity of the flow units in the main flow direction within the defined reservoir High degree of continuity Highly discontinuous. Difficult to predict/describe injector/producer connecting flow units. STOOIP density Describes the areal concentration of STOOIP and is defined as STOOIP/area (mill. Sm3/km2) >4.5 2-4.5 1-2.5-1 <.5 Coning tendency Describes the coning problems associated with a gas cap or aquifer support. Large complexity only in cases where the oil band is thin. No coning tendency. Some coning problems from gas cap or aquifer Thin oil zone and production severely restricted by gas or water coning problems 8.2.7 13
Important issues in estimating potential for different methods to increase recovery How is the remaining oil distributed in the reservoir? Temperature Fluid chemistry Mineralogy Topside facilities and wells Cost, both investment and operational Remaining field life Other issues 8.2.7 14
Reservoir temperature in fields on NCS Frigg Snøhvit Odin Troll Alvheim Alvheim Balder Alvheim Draugen Gullfaks Gullfaks Gullfaks Heimdal Grane Balder Gullfaks Glitne Tordis Tordis Snøhvit Jotun Tordis Heidrun Skirne Statfjord Valhall Statfjord Øst Snorre Tordis Urd Snøhvit Sleipner Øst Gullfaks Sør Statfjord Hod Snorre Statfjord Nord Ormen Lange Mikkel Brage Statfjord Sygna Statfjord Nord Norne Gullfaks Sør Sigyn Sigyn Hod Frøy Gullfaks Sør Visund Njord Njord Gullfaks Sør Sleipner Vest Gullfaks Sør Lille-Frigg Vale Varg Gullfaks Sør Cod Vest Ekofisk Ekofisk Edda Albuskjell Ula Huldra Kvitebjørn Kristin Tambar Embla Mime Kristin 18 16 14 12 Fields 8.2.7 15 1 8 6 4 2 Deg. C
Methods to improve injection? To obtain better sweep and produce by-passed oil? To reduce the residual oil saturation in the swept sone? Economical issues Environmental issues 8.2.7 16
Oil cost curve, including technological progress: availability of oil resources as a function of price 8.2.7 17
Cost and potential of Surfactant compared with other methods to increase recovery 8.2.7 18
Potential for surfactant flooding? In 1991 a work group in Statoil, Hydro a Saga and NPD estimated a technical potential from 8 to 13 MSm³ Based on an Sorw >.25 and immediate startup in 1 reservoirs Profitable reserves (potential) was estimated to 55 to 87 MSm³ including the condition of Seff > 4 Sm³ oil/ton surfactant Journal of Petroleum Science & Engineering, April 1992 What have16 years done to the potential? Is it time for a new potential study? 8.2.7 19