CN101747879A - Baffle for thin layer oilfield controlling coning of bottom water and injection method thereof - Google Patents

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

The 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 the chemical agent and the method for implanting thereof of bottom water coning at the thin layer oil reservoir.

Technical background:

Thin layer refers generally to the oil reservoir of core intersection less than 5m, because oil reservoir is thin, end water electrode easily awl proceeds to shooting of oil well section output.In case bottom-water breakthrough enters oil well, will cause water ratio increase in the oil well liquid-producing, oil offtake descends rapidly.The method of general control bottom water coning is to set up end water dividing plate near water-oil interface, basic skills is with the intensive perforation in the interval of 0.5m～2.0m on water-oil interface, with pkr the oil jacket annular space is separated, clamp-on dividing plate liquid (as silicic acid gel, chromium gel, resol etc.) by oil pipe to intensive perforation interval, can set up the dividing plate of 3～5m, bottom water coning is had control action kou preferably.But for oil sheet, find perforation interval accurately and sit accurate pkr 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 fluid and oil density difference generation gravitational differentiation, on water-oil interface, set up the dividing plate of control bottom water coning, effectively change end water and stream direction, thereby control bottom water coning, improve bottom aquifer drive oil efficient, improve the development effectiveness of thin layer bottom water reservoir.

Purpose of the present invention realizes like this: the dividing plate of control end water injects the stratum in order by density brine, dividing plate liquid and mistake displacing liquid and is constituted, and density brine is that mass concentration is 2.5%～10.0% sodium chloride aqueous solution, and its density is at 1.01gcm ^-3～1.16gcm ^-3Between; Dividing plate liquid is the gel-type blocking agent, and it is the selectivity blocking agent that can preferentially enter the high stratum of water saturation, is that to add massfraction in 0.2%～0.5% the HPAM aqueous solutions of polymers be 0.08%～0.30% Cr by massfraction ³⁺Linking agent is that to add massfraction 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 displacing liquid is that massfraction is 0.3%～0.5% HPAM aqueous solutions of polymers.

Above-specified high density salt solution, dividing plate liquid and mistake displacing liquid 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 displacing liquid, it is 6m that the total injection rate of displacing liquid 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 speed of above-mentioned working fluid is 3m ³H ^-1～5m ³H ^-1, injection pressure is no more than 80% of formation-parting pressure, and is no more than 4MPa with difference that working fluid initially enters reservoir pressure.

The invention has the beneficial effects as follows: owing in oil well, inject earlier density brine, 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 of Zhu Ruing is the selectivity 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 water-oil interface, build up dividing plate, that injects at last crosses displacing liquid because viscosity is higher, blocking agent is replaced oil-yielding stratum, be similar to piston-type ground the selectivity blocking agent in the water awl invasion passage is replaced near water-oil interface, make dividing plate liquid be trapped in the oil reservoir as few as possible, bore the displacing liquid 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.

Embodiment:

Specify the present invention below in conjunction with embodiment.

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

Dividing plate liquid is selected the frozen glue with selectively blocking off effect for use, 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 aquifer drive is walked, occupy the position that optimum is set up dividing plate.

Cross displacing liquid and select the HPAM polymers soln of viscosity more than or equal to the dividing plate fluid viscosity for use, purpose is that dividing plate liquid frozen glue piston-type is replaced oil-yielding stratum, near water-oil interface.

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

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

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

Table 1 test pit 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
Rate of permeation * 10 3/(μm 2)	????2971.326	????487.43
			Porosity * 10 2	????34.86	????22.75

Situation	The A well	The B well
			Water-oil interface/(m)	????1167	????2239.0～2241.0
Formation temperature/(℃)	????41.2	????65.6

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

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

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

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

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

Test-results shows that water ratio average out to 80% before the A well construction is up to 95%, and the construction back is minimum to be 33%, and is stabilized in about 60%, and oil offtake is by the preceding average 1.1td of construction ^-1Be increased to 5.0td ^-1, being valid up to 11 months, production gain reaches 1050t.Water ratio average out to 75% before the B well construction is up to 88%, and the construction back is minimum to be 42%, and is stabilized in about 65%, and oil offtake is by the preceding average 4.8td of construction ^-1Be increased to 6.6td ^-1, be valid up to 10 months, production gain 560t, effect is obvious.

Claims (2)

1. the dividing plate of a thin layer oil reservoir control bottom water coning injects the stratum in order by density brine, dividing plate liquid and mistake displacing liquid and is constituted, and it is characterized in that density brine is that massfraction is 2.5%～10% water-soluble chlorination sodium solution, and its density is at 1.01gcm ^-3～1.16gcm ^-3Between; Dividing plate liquid is the gel-type blocking agent, is that to add massfraction in 0.2%～0.5% the HPAM aqueous solutions of polymers be 0.08%～0.30% Cr by massfraction ³⁺Linking agent or be that to add massfraction in 0.2%～0.5% the HPAM aqueous solutions of polymers be that 0.2%～1.5% phenolic resin crosslinking agent is formed by mass concentration; Crossing displacing liquid is that massfraction is 0.3%～0.5% HPAM aqueous solutions of polymers.

2. control the method for implanting of the dividing plate of bottom water coning according to the described thin layer oil reservoir of claim 1, it is characterized in that injecting 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 displacing liquid, it is 6m that the total injection rate of displacing liquid 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 speed of above-mentioned working fluid is 3m ³H ^-1～5m ³H ^-1, injection pressure is no more than 80% of formation-parting pressure, and is no more than 4MPa with difference that working fluid initially enters reservoir pressure.