Method for improving crude oil recovery ratio by utilizing salt sensitive self-thickening polymer

A self-thickening and polymer technology, which is applied in drilling compositions, chemical instruments and methods, and mining fluids, can solve the problem of difficult control of gel strength and formation depth during freezing, and the effect of profile control and water blocking Weakness and limitations of large-scale application in mine fields, to achieve the effects of selective environmental friendliness, expansion of water flooding swept volume, and easy on-site injection

Active Publication Date: 2015-01-28
CHINA UNIV OF GEOSCIENCES (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The method of using bulk jelly to regulate, due to the shearing of the jelly on various equipment and formation pores during the implementation process, the chromatographic separation effect, the dilution of formation water, and the physical and chemical conditions of the formation (temperature, pressure, mineralization of formation water, etc.) degree) sensitive, so it is difficult to control the freezing time, the strength of the formed jelly and the depth into the formation
However, due to the limitation of the size of the particles, the method of using particles to control the formation is narrow, and its cost is high, which seriously limits the la

Method used

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  • Method for improving crude oil recovery ratio by utilizing salt sensitive self-thickening polymer
  • Method for improving crude oil recovery ratio by utilizing salt sensitive self-thickening polymer
  • Method for improving crude oil recovery ratio by utilizing salt sensitive self-thickening polymer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] The method of using salt-sensitive self-thickening polymer to control the dominant channel to improve oil recovery in Example 1 of the present invention is to slowly add 0.25 g of salt to the brine with a salinity of 60000 mg / L and a mass of 99.75 g while stirring Sensitive self-thickening polymer, mechanically stirred for 30-40min, then left to mature for 0.5-1.0h to obtain a 0.25% salt-sensitive self-thickening polymer solution, which was then placed in a 60°C thermostat. DV-Ⅱ Pro viscometer measures the change of viscosity of salt-sensitive self-thickening polymer solution system with time (such as figure 2 shown).

[0050] The polymer solution in Example 1 of the present invention had a thickening effect, and the viscosity of the system increased significantly.

Embodiment 2

[0052] The method for improving oil recovery by using salt-sensitive self-thickening polymer to control the dominant channel in Example 2 of the present invention is based on the evaluation index of the plugging rate of the rock core. The greater the plugging rate, the better the ability to control the dominant channel. OK, the operation steps are:

[0053] Three sand-packing pipes with a length of 20cm and an inner diameter of 2.5cm were filled with sand to prepare simulated cores, which were respectively recorded as No. 1, No. 2 and No. 3. After water flooding until the pressure was stable, the permeability before plugging was measured. k 1 ; Then inject 0.3 V p The (core pore volume) mass fraction is 0.25%, and the salinity of the dosing water is 60000mg / L salt-sensitive self-thickening polymer solution (the viscosity of the system can be increased from the initial 45mPa·s to 24000mPa·s after aging at 60°C for 5 days), Subsequent injection of 0.05 V p The water is over...

Embodiment 3

[0058] Example 3 of the present invention utilizes salt-sensitive self-thickening polymer to control the dominant channel to enhance the oil recovery method, which adopts a double-pipe sand-filled pipe core model (see Figure 4 ) to simulate heterogeneous formations with dominant channels, and then judge the ability of the salt-sensitive self-thickening polymer solution to regulate the dominant channels and the value of the oil recovery.

[0059] The implementation condition of the embodiment of the present invention 3 is:

[0060] The mass fraction of the salt-sensitive self-thickening polymer solution is 0.25%, and the salinity of the dosing water is 60000mg / L.

[0061] The above-mentioned salt-sensitive self-thickening polymer solution was used to carry out indoor core displacement experiments. The crude oil was dehydrated and degassed crude oil on the ground, and its viscosity at 60°C was 180mPa·s; the salinity of the simulated brine was 60,000mg / L; the experimental temper...

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Abstract

The invention relates to a method for improving the crude oil recovery ratio by utilizing a salt sensitive self-thickening polymer. The method comprises the following steps: firstly vacuum-pumping high and low sand filling tube cores respectively and saturating formation simulated water; respectively displacing the high and low sand filling tube cores at an injection sped of 1 mL/min by using simulated salt water and determining the pore volume and the permeability; saturating dehydrated and degassed ground crude oil at an injection speed of 1 mL/min; sealing the sand filling tube cores after the crude oil is saturated and then placing for 48 hours at a constant temperature; displacing the high and low sand filling tube cores which are connected in parallel at an injection speed of 1 mL/min and calculating the water drive recovery ratio; injecting a certain volume of salt sensitive self-thickening polymer solution at an injection sped of 1 mL/min and then injecting the stimulated salt water to carry out over displacement; sealing the high and low sand filling tube cores which are connected in parallel and placing for 120 hours at a constant temperature till the crude oil is thickened. The method has the benefits that the operation is simple and convenient, the injection property is good, the formation application scope is wide, and the water injection profile of a water injection formation can be effectively improved, and the crude oil recovery ratio is improved.

Description

technical field [0001] The invention relates to a technology for further enhancing crude oil recovery in the technical field of oil and gas field development engineering, in particular to a method for enhancing crude oil recovery by using a salt-sensitive self-thickening polymer. Background technique [0002] With the deepening of oilfield water injection development, the heterogeneity of the reservoir and the unfavorable oil-water mobility ratio cause the injected water to rush along the dominant channel, which greatly reduces the swept volume of the injected water. The uneven water flooding has further evolved into channeling between dominant channels, and the water flooding effect has further deteriorated, weakening the stable production foundation of the oil field. And there is still a large amount of remaining oil in the formation under the high water-cut stage, but the production degree of the reservoir is limited due to the serious differentiation of the reservoir, so...

Claims

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Application Information

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IPC IPC(8): E21B43/20E21B43/22C09K8/588
CPCC09K8/588E21B43/16E21B43/20
Inventor 由庆李卓静戴彩丽王凯赵光赵明伟赵健慧范洪富崔亚赵福麟
Owner CHINA UNIV OF GEOSCIENCES (BEIJING)
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