GullfaksVillage2012 IOR with a diverging agent from China Petter Eltvik Discipline leader Gullfaks Class ifica tion: Inter
Dec 29, 2015
GullfaksVillage2012 IOR with a diverging agent from China
Petter Eltvik
Discipline leader Gullfaks
Classification
: Interna
l 2012-01-11
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 3.3.4 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
5 - Classification: Internal 2011-08-18
GullfaksVillage2012 assignment - part B
Gullfaks flow diversion project
A-35
A-39A
A-38
A-38A
A-17
B-37
A-2AH
A-1H
A-5H
457200 457600 458000 458400
457200 457600 458000 458400
67
8200
06
782
400
67
8280
06
783
200
67
8360
06
784
000
67
820006
782400
67
828006
783200
67
836006
784000
Injection water
Oil 0.16
0.32
0.48
0.64
0.8
0.96
So
0 100 200 300 400 500m
1:10000
—— 01/06/2008 剩余油饱和度分布图
Bypassed oil
• R&D cooperation between Statoil and CNPC.
• 1000 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.
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:1.0-1.05 g/cm3
• suitable temperature: 30-200 oC, thermal stable for a long period in 140 oC
• 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 m3 every 500 m3. Chemicals are dissolved in
formation water)
Volume(m3)
Injection rate
(m3/d)
Injection
Pressure
(bar)
Combined effect in the two producers
Preliminary slug:1 % KCl 500
60-80
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 % KCl 1000
Main slug: 0.75 % A+0.5 % KCl 1100
Rear slug: 1 % KCl 500
Sedimentary condition: Fluvial – fractured.
Reservoir pressure, temperature and oil viscosity: 260 bar, 99 oC and 1,5 mPas.
Water type and salinity: NaHCO3 and 13700 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 2 - 5 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 H2S in A-39A. B-37 may also give a H2S
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