GullfaksVillage2012 IOR with a diverging agent from China Petter Eltvik Discipline leader Gullfaks Classif ication: Interna l

GullfaksVillage2012 assignment - part A 2 -Classification: Internal

GullfaksVillage2012 assignment - part A 3 -Classification: Internal The main purpose of Part A is to demonstrate an understanding of challenges related to tail-end production at Gullfaks main field: 1. Study the Gullfaks paper (Ref 2) and the Åm report (Ref 3). 2. Make an overview evaluation of the recovery factor for Gullfaks main field to date and how it varies across the field in the different fluid segments and formations (Brent, Cook, Statfjord and Lunde). From the Base Ness 1 structural map (Attachment in RSP07), locate the H1 segment which is relatively isolated. By looking at all the maps in RSP07 (Ref 1), make an estimate of how many similar independent segments there are at Gullfaks main field. With independent we mean that the pressure communication to the rest of the field is limited. Explain why there are differences in oil recovery between the different fluid segments and formations? 3. Based on the IOR measures in Section 5 in the Åm-report, rank measures according to the potential for the Gullfaks main field. List pro and contra for each of the IOR measure at Gullfaks main field

Some Norwegian IOR projects (Source Petoro) Classification: Internal

5 -Classification: Internal GullfaksVillage2012 assignment - part B Gullfaks flow diversion project Bypassed oil R&D cooperation between Statoil and CNPC ton chemicals bought from company in China. Injecting chemicals (silica based) into the injector A-35. The chemicals is classified as yellow, due to less than 1% of aluminates. It is environmentally acceptable and unproblematic to use. The chemicals shall move into the reservoir and form micro gel particles, which will stick to the surface of the pores and thereby reducing the permeability in invaded zones. The water will be forced to find new paths and invade less water flooded areas. Hit bypassed oil and increase the oil recovery.

6 -Classification: Internal Illustration of water diverging

7 -Classification: Internal Introduction to Abio gel Abio gel is compound, consisting primarily of Sodium silicate. When Abio gel is brought into contact with divalent cations (i.e. Ca and Mg) in formation- or seawater it reacts to form a microcrystalline suspension which may become a stiff gel if concentration of divalent cations exceeds about 1 %. Otherwise it behaves as a cement paint coating the rock matrix. Abiogel coat narrow the flow channels gradually keep certain permeability in favor of indepth fluid diversion The following text and illustration is provided by CNPC Abiogel is actually a gel used in chromatography and is also a brand name for cement paint

8 -Classification: Internal HMS Abio gel-A (Abio gel) are HMS tested to yellow. It is environmentally green but not on the PLONOR list and therefore yellow. It is yellow in health due to high pH. Abio gel-B (Calcium Chloride) is green and on the PLONOR list. Alternative chemicals from other suppliers are mostly red.

9 -Classification: Internal Main Technical Specifications of Abio gel* Main agent – Abio gel: milk white or white particles or powder Apperance of abio-gel: transparent or offwhite gelation time:4~24h density of gel: g/cm 3 suitable temperature: o C, thermal stable for a long period in 140 o C Salinity stability: no upper limit, the higher the better suitable reservoirs: sandstone or conglomerate with high permeability,high heterogeneity. For fractures and large pores are not suitable. Inorganic gel *:text and pictures from CNPC

10 -Classification: Internal Field experience with Abio gel in China To our knowledge CNPC has used Abio gel in several reservoirs in the Tarim and Dagang basins, covering a with a wide range of properties. In most cases the treatment has resulted in increased oil recovery Tarim basin Dagang basin

11 -Classification: Internal Zhouquingzhuang – Dagang oil field Example: Injector Qi24-1, supporting producers Qi24-3 and Qi24-6 Injection scheme for Abio gel (spacer fluid 20 m 3 every 500 m 3. Chemicals are dissolved in formation water) Volume (m 3 ) Injection rate (m 3 /d) Injection Pressure (bar) Combined effect in the two producers Preliminary slug:1 % KCl Between 220 and 300. Normal inj. pressure increases from about 258 to 275 Oil rate increased 100 %, watercut reduced from 63 to 41 % Front slug:1.5 % A+0.5 % KCl1000 Main slug: 0.75 % A+0.5 % KCl1100 Rear slug: 1 % KCl500 Sedimentary condition: Fluvial – fractured. Reservoir pressure, temperature and oil viscosity: 260 bar, 99 o C and 1,5 mPas. Water type and salinity: NaHCO 3 and mg/l Average values for porosity and permeability: 0,22 and 18 mD (generally some injection problems) Typical formation depth, thickness and well distance: 3150 m, 10 m and 300 m NB: solid gel is not formed in the reservoir in this case

12 Studied pilot area: Lower Brent, segment H1 Segment selected for a water based chemical method. STOOIP in lower Brent is 20,3 MSm³ oil. Lower Brent in H1 has ”only” 57 % recovery factor. Potential MSm³ mobile oil left. Relatively isolated segment. A lot of data is collected in this area. It was the first production area and therefore a lot of good, initial data. 2 active wells in lower Brent, A-35 (injector) and A- 39A (producer). 2 active producers in upper Brent, B-37 and A-38A. Pressure communication between B-37 and lower Brent. No communication with A-38A? Problem with H 2 S in A-39A. B-37 may also give a H 2 S problem.

13 -Classification: Internal IOR-challenge 1. Existing H1 model with faults and new production wells IOR-challenge 2. Existing H1 model with permeability modifications IOR-challenge 3. Existing H1 model with transmissibility multiplicators between cells IOR-challenge 4. Existing H1 model with permeability modifications and 2 chemicals. IOR-challenge 5. Existing H1 model with results from production log in A-35 IOR-challenge 6. Existing H1 model without consideration of environmental issues IOR-challenge 7. Modified H1 model to historymatch chemical injection in well A-35 GullfaksVillage2012 assignment - part B

14 -Classification: Internal H1 reservoir model Layer 44, ER-1Layer 48, R-2

15 -Classification: Internal Presentation title Presenters name Presenters title address, tel: Thank you