CN101058723A - Re-use agent for polymer after driving and injecting method thereof - Google Patents

Abstract

The invention discloses a reusing agent of residual ground polymer driven by polymer as well as injecting method, which is characterized by the following: adopting double-liquid method fixation agent and modified calcium soil as flocculant; allocating the fixation agent with 0. 09%-0. 54% Na2Cr2O7 solution and 0. 16%-0. 96% Na2SO3 solution with bulk rate at (0. 8-1. 2):1; making the flocculant as modified calcium soil added by Na2CO3 and NaHCO3. The injecting method comprises the following steps: injecting Na2Cr2O7 solution first and insulating liquid separately; injecting Na2SO3 solution and flocculant; injecting water normally. The invention can do deep adjusting and dissect for residual ground polymer, which can change the flowing direction of ground flow effectively and improves the recovery efficiency after driving by polymer.

Description

Residual polyalcohol utilizes agent and method for implanting thereof again behind the polymer flooding

Technical field:

The present invention relates in the Oil-Gas Field Development Engineering technical field further to improve the technology of oil recovery factor, utilize particularly behind the polymer flooding that residual polyalcohol carries out deep profile controlling in the stratum, improve the technology of oil recovery factor.

Technical background:

Oil field residual number of polymers in the stratum behind polymer flooding.According to statistics, when polymer flooding finishes, 75%～85% polymer residue that injects is arranged on the stratum, mainly the mode with dissolving, absorption and capture exists.

Proposed at present to utilize agent (comprising fixing agent and flocculation agent) again to the stratum injection of polymer, the polymkeric substance that the stratum is residual is fixed and is flocculated at most permeable zone, play the profile control effect, by changing the flow direction of resident fluid, improve the swept volume of follow-up water drive behind the polymer flooding, reach the purpose of further raising oil recovery factor.

Domestic and international research shows, the fixing agent that uses chromium acetate, chromium+oxalic acid, chromium propionate, Chromic lactate, chromium citrate, resol, urea-formaldehyde resin and cationic starch etc. to make the stratum residual polyalcohol is arranged, they all are the linking agents of polymkeric substance, by crosslinked action, the polymkeric substance that the stratum is residual is linked to be an integral body, is fixed on to play the profile control effect in the stratum; The flocculation agent that uses sodium soil, calcium soil, flyash, calcium hydroxide etc. to make the stratum residual polyalcohol is arranged, and they all can adsorb throwing out by the bridge joint of polymkeric substance, and formed flocs unit plays the profile control effect.

In order to change the flow direction of resident fluid effectively, should carry out profile control (being deep profile controlling) in well area far away, therefore there is following deficiency in above-mentioned fixing agent and flocculation agent: 1. above-mentioned fixing agent is the single-fluid process fixing agent, meet with polymkeric substance and promptly to play crosslinked action, if behind polymer flooding, inject immediately, the immediate vicinity of wellbore obstruction be can cause, the injection of back fixing agent and the performance of deep profile controlling effect influenced; 2. above-mentioned flocculation agent solid particulate all has certain settleability, and is influential to utilizing the deep formation residual polyalcohol to play the deep profile controlling effect.

Summary of the invention:

The stratum residual polyalcohol utilizes agent and method for implanting thereof again after the object of the present invention is to provide a kind of polymer flooding, make it can utilize the stratum residual polyalcohol to carry out deep profile controlling, change the flow direction of resident fluid effectively, the recovery ratio of follow-up water drive behind the raising polymer flooding.

Purpose of the present invention realizes as flocculation agent and corresponding method for implanting by adopting two-fluid process fixing agent and modified calcium soil.The two-fluid process fixing agent is 0.09%～0.54% Na by massfraction ₂Cr ₂O ₇Solution and massfraction are 0.16%～0.96% Na ₂SO ₃Solution composition, the volume ratio of two kinds of solution are (0.8～1.2): 1; Flocculation agent is to add Na in the calcium soil ₂CO ₃And NaHCO ₃Make the modified calcium soil water suspension of buffer reagent, calcium soil is 94: 6～98: 2 with the mass ratio of buffer reagent, and the massfraction of modified calcium soil water suspension is 3%～6%, Na in the buffer reagent ₂CO ₃With NaHCO ₃Mass ratio be (0.8～1.2): 1.

Behind the polymer flooding stratum residual polyalcohol utilize again the method for implanting of agent be will utilize again agent in dosing is irritated, be mixed with the aqueous solution, filter to go in the corresponding well by screen filter by the profile control infusion.Injection is in proper order: at first inject Na ₂Cr ₂O ₇Solution injects spacer pad (spacer pad is an oilfield injection water) then, and Na reinjects ₂SO ₃Solution injects flocculation agent at last, the normal water filling of becoming a full member.Fixing agent total consumption in 1m thickness stratum is 40～60m ³, the total consumption of flocculation agent is 140～180m ³, injection speed is 4～6m ³H ^-1, injection pressure is no more than 80% of formation-parting pressure, utilizes agent injection pressure and the difference of utilizing agent initially to enter reservoir pressure again to be no more than 4MPa again.

(from well 15m with interior area) produces obstruction because single-fluid process fixing agent and stratum residual polyalcohol meet promptly in the immediate vicinity of wellbore, so the present invention adopts Na ₂Cr ₂O ₇Solution+Na ₂SO ₃The two-fluid process fixing agent of solution does not all have crosslinked fixed action to polymkeric substance during these two kinds of solution Individual existences.After they mix, can be by reaction: Cr ₂O ₇ ^2-+ 3SO ₃ ^2-+ 8H ⁺→ 2Cr ³⁺+ 3SO ₄ ^2-+ 4H ₂O produces Cr ³⁺Polymkeric substance is played crosslinked fixed action, and inject this two kinds of working fluids sequentially, the centre separates with spacer pad, can be under the radial flow condition, two kinds of working fluids are met in well area far away (area beyond well 15m), the stratum residual polyalcohol is crosslinked fixing, play deep profile controlling.Flocculation agent adopts and add Na in calcium soil ₂CO ₃And NaHCO ₃The modified calcium soil of making, and the modified calcium soil particle has better suspending power than common sodium soil particle in water, institute join suspensoid at shearing rate 170s ^-1The time viscosity be 50～150mPas, have good pumpability.

Description of drawings:

Fig. 1 utilizes agent to inject schematic flow sheet according to stratum residual polyalcohol behind the polymer flooding provided by the present invention again.

Among the figure, 1-prepares water; 2-utilizes agent again; The 3-agitator; The 4-Agitation Tank; The 5-screen filter; 6-profile control pump; The 7-tensimeter; 8-tap manifold; The 9-under meter; 10-removes respectively to inject well.

Embodiment:

Specify the present invention below in conjunction with embodiment.

Because fixing agent is applicable to the mass concentration of stratum residual polyalcohol and surpasses 800mgL ^-1The stratum, flocculation agent then can be in polymer quality concentration at 200～800mgL ^-1Scope in still can play throwing out, therefore should inject fixing agent earlier, flocculation agent is injected in the back.

Generally, to penetrate the layer required fixing agent total consumption of turning up the soil be 40～80m to 1m thickness ³, wherein the volume ratio of two kinds of working fluids is (0.8～1.2): 1.It is 140～180m that 1m thickness is penetrated the required flocculation agent consumption of layer of turning up the soil ³

The spacer pad volume that injects between two kinds of working fluids is determined by following formula:

$V=\mathrm{\&pi;}({\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A20071001546600061.png"\; state="\{\{state\}\}">R</figure-callout>}}_2^2-{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A20071001546600061.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2)h\&CenterDot;\mathrm{\&phi;}\&CenterDot;\mathrm{\&alpha;}\&CenterDot;\mathrm{\&beta;}$

In the formula, V---spacer pad volume (m ³);

R ₂---spacer pad outer radius (m);

R ₁---spacer pad is interior along radius (m);

H---penetrate out layer thickness (m);

φ---formation porosity (%);

α---most permeable zone thickness accounts for penetrates out layer thickness percentage ratio (value 0.20);

β---direction coefficient (plane rate of permeation heterogeneity produces, value 0.75).

Work as R ₂-R ₁During≤0.20m, the spacer pad thin thickness is not to playing buffer action, and two working fluids meet and react, and have produced the Cr of crosslinked fixed polymer effect ³⁺

Because h, φ, α, β are known, if specify R ₂(R ₂〉=15m), can calculate the volume of spacer pad by following formula.

Utilize agent preferentially to inject most permeable zone again for making, injection speed is controlled at 6～10m ³H ^-1Utilize the injection pressure of agent to be no more than 80% of formation-parting pressure again; Utilize agent injection pressure and the difference of utilizing agent initially to enter reservoir pressure again to be no more than 4MPa again.

Existing two mouthfuls of test pits of A, B, its basic condition sees Table 1, and the polymer injection situation sees Table 2.

Table 1 test pit basic condition

Situation	The A well	The B well
			Perforated interval (m)	1262.0～1292.0	1278.0～1306.4
Perforation layer thickness (m)	30.0	28.4
			Formation temperature (℃)	70	70
Water injection pressure (MPa)	7.0	7.6
			Day fluence (m 3·d -1)	240	268

Table 2 test pit polymer injection situation

Situation	The A well	The B well
			The polymkeric substance relative molecular mass	1.6×10 7More than	1.6×10 7More than
Polymkeric substance hydrolysis degree (%)	25～30	25～30
			Polymers soln mass concentration (mgL -1)	1850～2000	1850～2000
Annotate the poly-time	2001.11～2004.6	2001.11～2004.6
			Polymers soln injection rate (m 3)	15.76×10 4	14.58×10 4
Injection of polymer dry powder amount (t)	385	377

During construction, the preparation massfraction is 0.30% Na in Agitation Tank 4 ₂Cr ₂O ₇Solution 1272m ³, inject 720m to the A well respectively by profile control pump 6 ³, inject 552m to the B well ³According to formula $V=\mathrm{\&pi;}({\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A20071001546600061.png"\; state="\{\{state\}\}">R</figure-callout>}}_2^2-{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A20071001546600061.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2)h\&CenterDot;\mathrm{\&phi;}\&CenterDot;\mathrm{\&alpha;}\&CenterDot;\mathrm{\&beta;},$ Get R ₂Be 20m, φ is 0.30, and α is 0.20, and β 0.75 calculates the volume of required spacer pad, injects spacer pad 28m to the A well then ³, inject spacer pad 22m to the B well ³The preparation massfraction is 0.53% Na in Agitation Tank 4 again ₂SO ₃Solution 1272m ³, inject A well 720m respectively ³, inject B well 552m ³After having annotated, the preparation massfraction is 4% modified calcium soil water suspension 6360m in Agitation Tank 4 ³, wherein, calcium soil is 96: 4 with the ratio of buffer reagent, injects 3600m to the A well respectively ³, inject 2760m to the B well ³, last metaideophone water.

Test-results shows, and is basicly stable with the daily fluid production rate of the corresponding oil well of A well, and daily oil production increases by 20%, and water ratio descends 5%; Descend 30% with the daily fluid production rate of the corresponding oil well of B well, daily oil production is basicly stable, and water ratio descends 3%, and effect is obvious.

Claims (5)

1. the stratum residual polyalcohol utilizes agent again behind the polymer flooding, is made up of fixing agent and flocculation agent, it is characterized in that fixing agent is the two-fluid process fixing agent, is 0.09%～0.54% Na by massfraction ₂Cr ₂O ₇Solution and massfraction are 0.16%～0.96% Na ₂SO ₃Solution composition, the volume ratio of two kinds of solution are (0.8～1.2): 1; Flocculation agent is to add Na in the calcium soil ₂CO ₃And NaHCO ₃Make the modified calcium soil water suspension of buffer reagent, calcium soil is 94: 6～98: 2 with the mass ratio of buffer reagent.

2. utilize agent again according to stratum residual polyalcohol behind the described polymer flooding of claim 1, the massfraction that it is characterized in that said modified calcium soil water suspension is 3%～6%.

3. utilize agent again according to stratum residual polyalcohol behind the described polymer flooding of claim 1, it is characterized in that Na in the said buffer reagent ₂CO ₃With NaHCO ₃Mass ratio be (0.8～1.2): 1.

4. the stratum residual polyalcohol utilizes the method for implanting of agent again behind the polymer flooding, it is characterized in that injecting in the following order:

A. inject Na ₂Cr ₂O ₇Solution;

B. annotate spacer pad;

C. annotate Na ₂SO ₃Solution;

D. annotate the modified calcium soil water suspension;

E. the normal water filling of becoming a full member.

5. according to the described method for implanting of claim 4, it is characterized in that fixing agent total consumption in 1m thickness stratum is 40～60m ³The flocculation agent consumption is 140～180m ³Injection speed is 4～6m ³H ^-1, injection pressure is no more than 80% of formation-parting pressure, utilizes agent injection pressure and the difference of utilizing agent initially to enter reservoir pressure again to be no more than 4MPa again.

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