西湖凹陷HY气田储层孔隙结构差异对其渗流特征的影响

The Influence of Differences in Pore Structure of HY Gas Field Reservoir in Xihu Depression on Its Permeability Characteristics

段冬平 刘彬彬 庞榆 时琼 李文俊 唐洪明

DUANDongping LIUBinbin PANGYu SHIQiong LIWenjun TANGHongming

中海石油(中国)有限公司上海分公司, 上海 长宁 200051 中国石油西南油气田公司勘探开发研究院, 四川 成都 610041 西南石油大学地球科学与技术学院, 四川 成都 610500

CNOOC China Limited, Shanghai Branch, Changning, Shanghai 200051, China Research Institute of Exploration and Development, Southwest Oil & Gas Field Company, PetroChina, Chengdu, Sichuan 610041, China School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China

微观孔隙结构的准确表征是评价储层资源量和产能的关键。以西湖凹陷HY气田花港组低渗致密砂岩储层为例，将低压氮气吸附、高压压汞和核磁共振技术相结合，全尺度表征其孔隙结构参数；结合稳态法气水相渗、可动流体饱和度实验，综合评价储层渗流机理及控制因素。结果表明，研究区由I类至IV类储层，储层样品的溶蚀孔比例增加、孔径逐渐变小，半径>1 μm的孔喉占比分别为50.7%、41.3%、25.2%、5.7%。随着孔隙结构质量变差，研究区的气水相对渗透率曲线向右偏移，束缚水饱和度为15%~55%；气相有效渗透率主要分布在0.01~9.00 mD，气水共渗范围水相含水饱和度为6%~65%；当返排压力梯度为9 MPa/m时，储层可动流体饱和度平均>50%，孔喉连通性较好；赋存于孔喉半径<0.1 μm的水呈水膜，占比越大则储层渗流能力越差。研究成果对于该区制定合理的开发对策和预测气井产能都具有指导意义。

Accurate characterization of microscopic pore structure is the key to evaluating reservoir resources and productivity. Taking the low-tight permeability sandstone reservoir of the Huagang Formation in the HY Gas Field of the Xihu Depression as an example, pore structure parameters are characterized on a full-scale basis by combining low-pressure nitrogen adsorption, high-pressure mercury injection, and nuclear magnetic resonance technology. Combined with the steady-state gas-water relative permeability and movable fluid saturation experiments, the reservoir seepage mechanism and control factors are comprehensively evaluated. The results show that the proportion of dissolved pores in reservoir samples increases, and the pore size decreases gradually from type I to type IV reservoirs in the study area. The proportions of pore throats with radius greater than 1 μm are 50.7%, 41.3%, 25.2% and 5.7%, respectively. With the deterioration of pore structure quality, the gas-water relative permeability curve in the study area shifts to the right, and the irreducible water saturation ranges from 15% to 55%. The effective permeability of the gas phase ranges from 0.01 to 9.00 mD, and the water saturation in the range of gas-water co-seepage is 6%~65%. When the flowback pressure gradient is 9 MPa/m, the average movable fluid saturation of the reservoir exceeds 50%, and the pore throat connectivity is good. The water film occurs in the pore throat radius μm. The reservoir seepage capacity is worse where a larger proportion of the water film. The research results have significant guidance for formulating effective development countermeasures and predicting gas well productivity in this area.

10.11885/j.issn.1674-5086.2024.04.12.04