How to Select Polymer Molecular Weight and Concentration to Avoid Blocking in Polymer Flooding?

Guo, Hu

doi:10.2118/189255-ms

Cited by 27 publications

(17 citation statements)

References 40 publications

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“…The higher the concentration of polymer in ASP solution, the denser the spatial network structure and the coarser the molecular framework, as can be seen from the SEM images. As the molecular weight of the polymer increases at the same concentration, the molecular structure of ASP solution with high molecular weight is coarser and the spatial network structure is denser [15,51,52,53]. The microstructure morphology of ASP solution prepared by polymer with a molecular weight of 25 million is similar to that of ASP solution with molecular weights of 16 million and 19 million.…”

Section: Resultsmentioning

confidence: 99%

“…The method has been applied to the secondary oil recovery project in Daqing Oilfield, and the recovery ratio has been increased by more than 8%. Hu et al [15] studied the maximum allowable molecular weight of polymer and the concentration under given permeability through core flow experiments. The results show that too high viscosity and molecules will block the low permeability layer.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Morphology and Viscoelasticity of ASP Solution under the Action of a Different Medium Injection Tool

Huang

et al. 2019

Polymers

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In order to improve the oil displacement effect of alkali/surfactant/polymer (ASP) solution in low-permeability oil layers, Daqing Oilfield has proposed a separate injection technology. The objective of separate injection technology is to reduce the viscosity of ASP solution through a different medium injection tool and increase the injection amount of ASP solution in low permeability oil layer, thus improving the oil displacement effect. In order to study the effect of the different medium injection tool on ASP solution, SEM is used to observe the changes in molecular micromorphology before and after the ASP solution flows through the tool. Then, the influence of the tool on viscosity and the first normal stress difference of the solution are studied through static shear experiments. Finally, the storage and loss modulus of the solution are measured through dynamic mechanical experiments and the relaxation time and zero shear viscosity of the solution are verified and compared. The results show that molecular chains are obviously broken and the grid structure is destroyed after the ASP solution is acted on by the different medium injection tool. The viscosity and elasticity of ASP solution decrease, and the influence degree of the different medium injection tool on viscosity is greater than elasticity. The results of the steady shear experiment and dynamic mechanics experiment are consistent. Therefore, the different medium injection tool can achieve the purpose of use, which is conducive to the injection of displacement fluid into low-permeability oil layers and enhance the recovery ratio.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular Morphology and Viscoelasticity of ASP Solution under the Action of a Different Medium Injection Tool

Huang

et al. 2019

Polymers

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“…Selected in SP Flooding. If polymer concentration and viscosity is too high, strata may be blocked [122,123]. If polymer centration and viscosity is too low, the mobility reduction is inadequate.…”

Section: Polymer Viscosity and Concentration Should Be Carefullymentioning

confidence: 99%

Recent Advances of Surfactant-Polymer (SP) Flooding Enhanced Oil Recovery Field Tests in China

Sun

Guo

et al. 2020

Geofluids

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Recently, there are increasing interests in chemical enhanced oil recovery (EOR) especially surfactant-polymer (SP) flooding. Although alkali-surfactant-polymer (ASP) flooding can make an incremental oil recovery factor (IORF) of 18% original oil in place (OOIP) according to large-scale field tests in Daqing, the complex antiscaling and emulsion breaking technology as well as potential environment influence makes some people turn to alkali-free SP flooding. With the benefit of high IORF in laboratory and no scaling issue to worry, SP flooding is theoretically better than ASP flooding when high quality surfactant is available. Many SP flooding field tests have been conducted in China, where the largest chemical flooding application is reported. 10 typical large-scale SP flooding field tests were critically reviewed to help understand the benefit and challenge of SP flooding in low oil price era. Among these 10 field tests, only one is conducted in Daqing Oilfield, although ASP flooding has entered the commercial application stage since 2014. 2 SP tests are conducted in Shengli Oilfield. Both technical and economic parameters are used to evaluate these tests. 2 of these ten tests are very successful; the others were either technically or economically unsuccessful. Although laboratory tests showed that SP flooding can attain IORF of more than 15%, the average predicted IORF for these 10 field tests was 12% OOIP. Only two SP flooding tests in (SP 1 in Liaohe and SP 7 in Shengli) were reported actual IORF higher than 15% OOIP. The field test in Shengli was so successful that many enlarged field tests and industrial applications were carried out, which finally lead to a commercial application of SP flooding in 2008. However, other SP projects are not documented except two (SP7 and SP8). SP flooding tests in low permeability reservoirs were not successful due to high surfactant adsorption. It seems that SP flooding is not cost competitive as polymer flooding and ASP flooding if judged by utility factor (UF) and EOR cost. Even the most technically and economically successful SP1 has a much higher cost than polymer flooding and ASP flooding, SP flooding is thus not cost competitive as previously expected. The cost of SP flooding can be as high as ASP flooding, which indicates the importance of alkali. How to reduce surfactant adsorption in SP flooding is very important to cost reduction. It is high time to reevaluate the potential and suitable reservoir conditions for SP flooding. The necessity of surfactant to get ultra-low interfacial tension for EOR remains further investigation. This paper provides the petroleum industry with hard-to-get valuable information.

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“…However, high injection speed should be avoided due to turbulent flow of polymer solution through the different-medium-injection-tool. So as to reduce energy loss and dissipation [21]. The polymer rheology in the flow process of different-medium-injection-tools can determine the largest polymer solution injection rate to improve oil recovery and reduce the development cost which has practical value in engineering [22].…”

Section: Introductionmentioning

confidence: 99%

Study Rheological Behavior of Polymer Solution in Different-Medium-Injection-Tools

Huang

et al. 2019

Polymers

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Previous studies showed the difficulty during polymer flooding and the low producing degree for the low permeability layer. To solve the problem, Daqing, the first oil company, puts forward the polymer-separate-layer-injection-technology which separates mass and pressure in a single pipe. This technology mainly increases the control range of injection pressure of fluid by using the annular de-pressure tool, and reasonably distributes the molecular weight of the polymer injected into the thin and poor layers through the shearing of the different-medium-injection-tools. This occurs, in order to take advantage of the shearing thinning property of polymer solution and avoid the energy loss caused by the turbulent flow of polymer solution due to excessive injection rate in different injection tools. Combining rheological property of polymer and local perturbation theory, a rheological model of polymer solution in different-medium-injection-tools is derived and the maximum injection velocity is determined. The ranges of polymer viscosity in different injection tools are mainly determined by the structures of the different injection tools. However, the value of polymer viscosity is mainly determined by the concentration of polymer solution. So, the relation between the molecular weight of polymer and the permeability of layers should be firstly determined, and then the structural parameter combination of the different-medium-injection-tool should be optimized. The results of the study are important for regulating polymer injection parameters in the oilfield which enhances the oil recovery with reduced the cost.

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How to Select Polymer Molecular Weight and Concentration to Avoid Blocking in Polymer Flooding?

Cited by 27 publications

References 40 publications

Molecular Morphology and Viscoelasticity of ASP Solution under the Action of a Different Medium Injection Tool

Molecular Morphology and Viscoelasticity of ASP Solution under the Action of a Different Medium Injection Tool

Recent Advances of Surfactant-Polymer (SP) Flooding Enhanced Oil Recovery Field Tests in China

Study Rheological Behavior of Polymer Solution in Different-Medium-Injection-Tools

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