CN101747879B

CN101747879B - Baffle for thin layer oilfield controlling coning of bottom water and injection method thereof

Info

Publication number: CN101747879B
Application number: CN 200910256525
Authority: CN
Inventors: 戴彩丽; 赵福麟
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2009-12-15
Filing date: 2009-12-15
Publication date: 2013-05-01
Anticipated expiration: 2029-12-15
Also published as: CN101747879A

Abstract

The invention provides a baffle for a thin layer oilfield controlling coning of bottom water and an injection method thereof. The baffle is formed by sequentially injecting high density salt water, baffle fluid and overdisplacing fluid into a formation, wherein the high density salt water is 2.5-10 percent of water soluble sodium chloride solution, the baffle fluid is a gel plugging agent formed by adding 0.08-0.30 percent of Cr3+ crosslinking agent in 0.2-0.5 percent of HPAM polymer aqueous solution or adding 0.2-1.5 percent of phenolic resin crosslinking agent in the 0.2-0.5 percent of HPAM polymer aqueous solution, and the overdisplacing fluid is an HPAM polymer aqueous solution with the mass ratio of 0.3-0.5 percent. Injected working fluid is utilized to generate a gravity differentiation function with crude oil and bottom water density difference, and the baffle used for controlling coning of thin layer bottom water is established on an oil-water interface without perforation, thereby efficiently changing the flow around direction of the bottom water and enhancing the recovery ratio of a thin layer bottom water oil reservoir.

Description

Dividing plate and the method for implanting thereof of thin layer oil reservoir control bottom water coning

Technical field:

The present invention relates to a kind of oilfield chemistry agent, especially control chemical agent and the method for implanting thereof of bottom water coning for the thin layer oil reservoir.

Technical background:

Thin layer refers generally to core intersection less than the oil reservoir of 5m, because oil reservoir is thin, end water electrode easily cone proceeds to oil well perforation section output.In case bottom-water breakthrough enters oil well, will cause moisture content increase in the oil well liquid-producing, oil production descends rapidly.The method of general control bottom water coning is to set up end water dividing plate near oil-water interfaces, basic skills is with the intensive perforation in the interval of 0.5m～2.0m on oil-water interfaces, with packer the oil jacket annular space is separated, clamp-on dividing plate liquid (such as silicic acid gel, chromium gel, phenolic resins etc.) by oil pipe to intensive perforated interval, can set up the dividing plate of 3～5m, bottom water coning is had preferably control action.But for oil sheet, find perforated interval accurately and sit accurate packer just has sizable difficulty, therefore, sets up the method for end water dividing plate and is difficult to adapt to oil sheet with the perforation that passes through of routine.

Therefore the present invention proposes the method that a kind of not perforation is set up end water dividing plate,

Summary of the invention:

The objective of the invention is to provide a kind of dividing plate and method for implanting thereof of thin layer oil reservoir control bottom water coning, utilize and inject working solution and the poor generation gravitational differentiation of oil density, set up the dividing plate of control bottom water coning at oil-water interfaces, effectively change end water and stream direction, thereby control bottom water coning, improve bottom water drive oil efficient, improve the development effectiveness of thin-layer oil reservoir with bottom water.

Purpose of the present invention realizes like this: the dividing plate of control end water injects in order the stratum by density brine, dividing plate liquid and mistake displacement fluid and is consisted of, and density brine is that mass concentration is 2.5%～10.0% sodium-chloride water solution, and its density is at 1.01gcm ^-3～1.16gcm ^-3Between; Dividing plate liquid is gel plugging agent, and it is the selective blocking agent that can preferentially enter the high stratum of water saturation, is that to add mass fraction in 0.2%～0.5% the HPAM aqueous solutions of polymers be 0.08%～0.30% Cr by mass fraction ³⁺Crosslinking agent is that to add mass fraction in 0.2%～0.5% the HPAM aqueous solutions of polymers be 0.2%～1.5% phenolic resin crosslinking agent by mass concentration perhaps; Crossing displacement fluid is that mass fraction is 0.3%～0.5% HPAM aqueous solutions of polymers.

Above-specified high density salt solution, dividing plate liquid and mistake displacement fluid inject according to the following steps:

A. inject density brine, the total injection rate of every 1m thickness stratum density brine is 40m ³～60m ³

B. annotate dividing plate liquid, the total injection rate of every 1m thickness stratum dividing plate liquid is 80m ³～120m ³

C. annotated displacement fluid, it is 6m that the total injection rate of displacement fluid is crossed on every 1m thickness stratum ³～10m ³

D. closing well is 5 days;

E. drive a well and resume production.

The injection rate of above-mentioned working solution is 3m ³H ^-1～5m ³H ^-1, injection pressure is no more than 80% of formation fracture pressure, and is no more than 4MPa with difference that working solution initially enters strata pressure.

The invention has the beneficial effects as follows: owing in oil well, injecting density brine first, this salt solution will enter bottom aquifer along end water invasion passage, and flatly to diffusion all around, set up the density brine layer, thereafter the dividing plate liquid that injects is selective blocking agent, because density is between oil reservoir oil density and the density brine density, so it will be positioned under the oil reservoir, on the brine layer, near oil-water interfaces, build up dividing plate, that injects at last crosses displacement fluid because viscosity is higher, blocking agent is replaced oil-yielding stratum, be similar to piston type ground the selective blocking agent in the water cone invasion passage is replaced near oil-water interfaces, make dividing plate liquid be trapped in as few as possible in the oil reservoir, bore the displacement fluid of crossing of invading in the passage and stay water, will when oil well resumes production, be taken away gradually by the oil reservoir production fluid.

The specific embodiment:

Specify the present invention below in conjunction with embodiment.

The dividing plate of control end water injects in order bottom by density brine, dividing plate liquid and mistake displacement fluid and is consisted of, and density brine is prepared with sodium chloride, requires the density ratio preparation of density brine to have 0.05gcm at least with water density ^-3Raising.Can produce considerable influence to the performance of dividing plate liquid frozen glue for fear of density brine, can set up the transition density brine layer at the density brine layer, generally adopt the method for exponential decrease to set up.If select the density brine of 10% sodium chloride, on it in transition density brine layer the mass fraction of sodium chloride should be 5% and 2.5%.

Dividing plate liquid is selected the frozen glue with selective shut-off effect, requires its gelation time to reach 1～5 day, and its density occupy between oil and the brine density.After it enters bottom aquifer, will be positioned under the oil reservoir, on the brine layer.Simultaneously because its high viscosity, so but its piston type ground bottom water drive is walked, occupy the position that optimum is set up dividing plate.

Cross displacement fluid and select viscosity more than or equal to the HPAM polymer solution of dividing plate fluid viscosity, purpose is that dividing plate liquid frozen glue piston type is replaced oil-yielding stratum, until near the oil-water interfaces.

Generally, total consumption of every 1m thickness stratum density brine is 40～60m ³, dividing plate liquid consumption is 80～120m ³, crossing the displacement fluid consumption is 6～10m ³

For making working solution preferentially enter the bottom water coning passage to enter bottom aquifer, reduce the pollution to oil sheet, injection rate is 3m ³H ^-1～5m ³H ^-1, injection pressure is no more than 80% of formation fracture pressure, and the difference that working solution injection pressure and working solution initially enter strata pressure is no more than 4MPa.

Existing A, two mouthfuls of test wells of B, its basic condition sees Table 1, and the working solution situation sees Table 2, table 3.

Table 1 test well basic condition

Situation	The A well	The B well
			Commissioning date	March 28 calendar year 2001	5 say May calendar year 2001
The producing horizon position	K ₁h ₂ ³	J ₂X ₄
			Oil reservoir well section/(m)	1161.875～1166.375	2225.7～2231.3
Perforated interval/(m)	1162.0～1165.0	2228.0～2231.0
			Sedimentary rhythm	The anti-rhythm	Positive rhythm
Permeability * 10 ³/(μm ²)	2971.326	487.43
			Degree of porosity * 10 ²	34.86	22.75
Oil-water interfaces/(m)	1167	2239.0～2241.0
			Formation temperature/(℃)	41.2	65.6

Table 2A test well working solution applicable cases (41 ℃ of well temperature)

* under the reservoir temperature, the density of formation water is 0.9638gcm ^-3, the density of oil is 0.876gcm ^-3

Table 3B test well working solution applicable cases (65 ℃ of well temperature)

* under the reservoir temperature, the density of formation water is 0.9532gcm ^-3, the density of oil is 0.798gcm ^-3

During construction, then implantation quality mark density brine from high to low injects the dividing plate liquid that gelation time is respectively 5 days, 3 days, 1 day successively, injects at last displacement fluid, and closing well 5 weathers are solidifying, drive a well and resume production.

Result of the test shows, moisture content average out to 80% before the A well construction is up to 95%, and minimum after the construction is 33%, and is stabilized in about 60%, oil production by construction before average 1.1td ^-1Be increased to 5.0td ^-1, being valid up to 11 months, production gain reaches 1050t.Moisture content average out to 75% before the B well construction is up to 88%, and minimum after the construction is 42%, and is stabilized in about 65%, and oil production is by the front average 4.8td of construction ^-1Be increased to 6.6td ^-1, be valid up to 10 months, production gain 560t, successful.

Claims

1. the method for implanting of the dividing plate of thin layer oil reservoir control bottom water coning, it is characterized in that injecting in order the stratum by density brine, dividing plate liquid and mistake displacement fluid is consisted of, described density brine is that mass concentration is 2.5%～10.0% sodium-chloride water solution, and its density is at 1.01gcm ^-3～1.16gcm ^-3Between; Described dividing plate liquid is gel plugging agent, is that to add mass fraction in 0.2%～0.5% the HPAM aqueous solutions of polymers be 0.08%～0.30% Cr by mass fraction ³⁺Crosslinking agent or be that to add mass fraction in 0.2%～0.5% the HPAM aqueous solutions of polymers be that 0.2%～1.5% phenolic resin crosslinking agent forms by mass concentration; Described excessively displacement fluid is that mass fraction is 0.3%～0.5% HPAM aqueous solutions of polymers; Described density brine, dividing plate liquid and mistake displacement fluid inject according to the following steps:

D. closing well is 5 days;

E. drive a well and resume production;