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Mechanism and Oil Displacement of Heavy Oil Emulsification and Viscosity Reducer：A Case Study on Heavy Oil Reservoir and Fluid Conditions of Bohai Oilfield

Xu Guorui, Li Xiang, Xie Kun

Abstract （276）

PDF （2593KB）（58）

In order to further explore the mechanism of “increasing oil and decreasing viscosity” of heavy oil emulsification and viscosity reducer, experimental studies on oil displacement of heavy oil emulsification and viscosity reducer and its influencing factors have been carried out. Viscosity reducer was screened and related performance was evaluated.The viscosity and recovery efficiency were used as evaluation indexaccording to the geological characteristics and fluid properties in Bohai reservoir. The results showed that, the mechanism of decreasing viscosity of three kinds of viscosity reducer was forming oil in water emulsion, and the viscosity reduction effect of “viscosity reducer 2” was best among three kinds of viscosity reducer. Oil water emulsion gradually changed from oil in water (O/W) into water in oil(W/O) type and the viscosity was increased when the water content in emulsion decreased, eventually exceeding that of crude oil. Besides, with the heavy oil reservoir hetergeneity increasing, oil displacement of viscosity reducer got better. Oil displacement of viscosity reducer got worse with the increasing of curde oil viscosity, so the recovery amplification can be increased through preprocessing on viscosity reduction before similarty viscosity reducer was used.

2016, 29 (1): 57-62. DOI: 10.3969/j.issn.1006-396X.2016.01.011

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Profile Control and Flooding Effect of Alternate Injection of Cr3+ Polymer Gel and Water and Its Mechanism Analysis: Taking the Bohai Oilfield as an Example

Zhang Baoyan, Lu Xiangguo, Xie Kun, Liu Yigang, Zhang Yunbao

Abstract （305）

PDF （2648KB）（64）

Aiming at technical demand on relieving the reverse of imbibition profile, displacement effect of alternate injection of Cr3+ polymer gel and water was studied, taking reservoir of Bohai oilfield as simulation object, regarding injection pressure, water content and recovery efficiency as evaluation index. Results showed that as the displacement agent flowed into the medium and low permeability layer, on the one hand, the swept volume was magnified. On the other hand, seepage resistance and start up pressure of imbibition were increased, thus resulting in the reverse of the imbibition profile. Once the alternate injection of Cr3+ polymer gel and water was adopted, polymer solution could get priority to flow into the high permeable layer and block off it, then subsequent water flowed into medium and low permeability layers to displace the oil. Therefore the phenomenon of the reverse of imbibition profile was relieved or even eliminated. Once the alternate injection of C3+ polymer gel and water was conducted in A22 injection well in LD5 - 2 Oilfield, injection pressure get increased, which was good for enlarging sweep volume effect.

2016, 29 (1): 35-40. DOI: 10.3969/j.issn.1006-396X.2016.01.007

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Effect of Solvent Water pH on Intramolecular Rosslinked  Gelation Performance of Cr ^3+ Polymer Gel

Xie Kun, Lu Xiangguo, Cao Bao, et al

Abstract （396）

PDF （2566KB）（351）

In order to further explore intramolecular rosslinked gelation mechanism of Cr ^3+ polymer gel under different pH conditions, effect of pH on Cr ^3+  polymer gel gelation performance was researched. Polymer gelformulation composition with good gelation performance was obtained by orthogonal experiment taking polymer mass concentration, water solution salinity and "polymer/Cr ^3+ " as the influence factors, aimed at Daqing Lamadian oilfield geological characteristics and fluid properties. The results showed that acidic conditions could promote ionization of chromium acetate and increase the number of Cr ^3+  in solution, thus increase the probability of coordination reaction between carboxyl in polymer chains and polynuclear olation complex ion, which is in favor of the formation of intramolecular crosslinked Cr ^3+  polymer gel system. The number of OH ^- was increased with solvent water pH, which could result in the reduction of Cr ^3+  involved in crosslinking reaction and gelation performance getting worse accordingly. when the system was similar to intramolecular crosslinked Cr ^3+  polymer gel, gelation performance of polymer gel system can be further improved by appropriately reducing pH value of solvent water.

2015, 28 (4): 69-74. DOI: 10.3969/j.issn.1006-396X.2015.04.015