Liu Jianbin, Zhong Liguo, Ren Lei, Hao Tongchun, Wang Cheng, Liu Yigang, Jiang Youwei, Zhou You
China University of Petroleum-Beijing, Beijing 102249, China.
China National Offshore Oil Corp-Tianjin, Tianjin 300451, China.
ACS Omega. 2020 Dec 24;6(1):623-632. doi: 10.1021/acsomega.0c05148. eCollection 2021 Jan 12.
Heavy oil emulsions such as water in oil (W/O), oil in water (O/W), and water in oil in water (W/O/W) would be formed during the development of heavy oil reservoirs. The key to the efficient development of heavy oil reservoirs is to clarify the fluidity of heavy oil emulsions in formation pores medium. In this study, the main factors that determine the fluidity of heavy oil emulsion were analyzed under the condition of simulating the formation pores medium. The reasons for the difference between the viscosity of heavy oil emulsions in formation pores medium and the viscosity measured by laboratory rheometer were analyzed. Then, experiments have confirmed the shortcomings of the current screening and evaluation method of emulsified viscosity reducer. Finally, through experimental research and mechanism analysis, the mechanism of the emulsified viscosity reducer was studied and suggestions were made to improve the effect of emulsified viscosity reducer in the oil field. When heavy emulsions flow in a formation pores medium, since the size of the droplets would be larger than the size of the pores medium, when the heavy emulsion passes through the pores medium, it would receive additional resistance brought by the Jiamin effect. But when a rheometer is used for viscosity testing, this additional resistance is almost nonexistent. Therefore, the current method of viscosity test using rheometer cannot fully reflect the actual flow state of heavy oil emulsion in formation pores medium. The research in this paper proves that the larger the droplets of the emulsion, the less accurate the rheometer test results. Temperature, permeability, oil-water ratio, and the type of emulsified viscosity reducer all have a certain effect on the flow of heavy oil emulsion in formation pores medium. This article evaluated four types of emulsified viscosity reducers. When the viscosity test was performed by a rheometer, the results showed excellent viscosity-reducing effects. However, when simulating formation pores medium conditions, the effects of some types of emulsified viscosity reducers are not so good. It is no longer accurate to judge the effect of emulsified viscosity reducer by the way of measuring viscosity with a rheometer. It should be screened by the flow capacity of the heavy oil emulsions in formation pores medium. In oil field development, the contact area of heavy oil and emulsified viscosity reducer solution should be increased as much as possible and provide more time for the substitution effect of emulsified viscosity reducer molecules.
在稠油藏开发过程中会形成油包水（W/O）、水包油（O/W）和水包油包水（W/O/W）等稠油乳液。稠油藏高效开发的关键在于明确稠油乳液在地层孔隙介质中的流动性。本研究在模拟地层孔隙介质条件下，分析了决定稠油乳液流动性的主要因素，剖析了稠油乳液在地层孔隙介质中的黏度与实验室流变仪测量黏度存在差异的原因。随后，实验证实了当前乳化降黏剂筛选与评价方法的不足。最后，通过实验研究和机理分析，对乳化降黏剂的作用机理进行了研究，并就提高乳化降黏剂在油田中的效果提出了建议。当稠油乳液在地层孔隙介质中流动时，由于液滴尺寸大于孔隙介质尺寸，稠油乳液通过孔隙介质时会受到贾敏效应带来的额外阻力。但使用流变仪进行黏度测试时，这种额外阻力几乎不存在。因此，当前使用流变仪进行黏度测试的方法不能充分反映稠油乳液在地层孔隙介质中的实际流动状态。本文研究表明，乳液液滴越大，流变仪测试结果越不准确。温度、渗透率、油水比以及乳化降黏剂类型均对稠油乳液在地层孔隙介质中的流动有一定影响。本文对四种类型的乳化降黏剂进行了评价。用流变仪进行黏度测试时，结果显示出优异的降黏效果。然而，在模拟地层孔隙介质条件时，某些类型的乳化降黏剂效果并不理想。用流变仪测量黏度的方式来判断乳化降黏剂的效果已不再准确。应通过稠油乳液在地层孔隙介质中的流动能力进行筛选。在油田开发中，应尽可能增加稠油与乳化降黏剂溶液的接触面积，并为乳化降黏剂分子的置换作用提供更多时间。
