水基压裂液对致密砂岩气层的损害机理——基于《水基压裂液性能评价方法:SY/T 5107—2016》的改进  

Damage mechanism of water-based fracturing fluid to tight sandstone gas reservoirs: Improvement of The Evaluation Measurement for properties of Water-based Fracturing Fluid: SY/T 5107-2016

作　　者：唐洪明[1] 唐浩轩 何江[1] 赵峰[1] 张烈辉[2] 廖纪佳[1] 王茜 袁学芳[3] TANG Hongming;TANG Haoxuan;HE Jiang;ZHAO Feng;ZHANG Liehui;LIAO Jijia;WANG Qian;YUAN Xuefang(School of Geosciences and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China;State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation//Southwest Petroleum University,Chengdu,Sichuan 610500,China;Oil and Gas Engineering Research Institute,PetroChina Tarim Oilfield Company,Korla,Xinjiang 841000,China)

机构地区：[1]西南石油大学地球科学与技术学院,四川省成都市610500 [2]“油气藏地质及开发工程”国家重点实验室·西南石油大学 [3]中国石油塔里木油田公司油气工程研究院

出　　处：《天然气工业》2020年第9期55-63,共9页Natural Gas Industry

基　　金：国家自然科学基金重点项目“致密气藏储层干化、提高气体渗流能力的基础研究”(编号:51534006)。

摘　　要：目前,针对压裂液的损害评价主要参考《水基压裂液性能评价方法 :SY/T 5107—2016》(以下简称行业标准),而行业标准设定的压裂液驱替岩心过程与实际压裂施工中压裂液高压快速侵入储层的过程不吻合,并且压裂液损害评价实验未考虑压裂液残渣、破胶方式、原始含水饱和度等因素的影响,从而影响了评价结果准确性。为此,选取塔里木盆地库车坳陷迪北地区下侏罗统阿合组(J1a)致密砂岩岩心,通过改进实验流程与方法来模拟压裂液侵入致密砂岩气层的过程,评价了压裂液对气层的损害程度,进而系统剖析了损害机理。研究结果表明:①改进后的压裂液损害评价方法,考虑了气层的原始含水饱和度(小于束缚水饱和度)、压裂过程中的高压瞬间"击穿"效应、压裂液残渣等因素的影响,能更加客观地评价压裂液对致密砂岩气层的损害程度;②基于行业标准的评价结果显示,压裂液对致密砂岩气层渗透率的损害程度为中等偏强,而改进后方法得到的损害程度则为中等偏弱;③压裂液残渣滞留于裂缝中是对渗透率造成损害的主要因素,残渣易堵塞裂缝与缝面孔,绝大多数残渣滞留在基质岩心表层(侵入深度小于3 cm)孔隙中,基质孔隙对残渣有过滤作用;④压裂液从岩心表面向内部运移的过程中,高分子聚合物依次以薄膜层状、局部片团状、晶体包裹状滞留于储层孔隙中;⑤实验条件下,岩心中会产生盐析晶体,盐析晶体在岩心中分布不均,裂缝中盐析晶体与高分子聚合形成复合包裹体,基质孔隙中盐析晶体与少量伊利石等碎片包裹形成复合体;⑥速敏产生的运移微粒通常与残渣、高分子聚合物等形成复合包裹体,进而堵塞裂缝与孔隙。At present, evaluation on reservoir damage induced by fracturing fluid mainly refers to The Evaluation Measurement for Properties of Water-based Fracturing Fluid: SY/T5107-2016(referred to as the industry standard below). However, the fracturing fluid displacing core process stipulated in the industry standard is not consistent with the fast invading process of fracturing fluid into the reservoir under high pressure during the actual fracturing construction. besides, the influences of fracturing fluid residue, gel breaking mode, original water saturation and other factors are not taken into consideration in the experiments to evaluate the damage of fracturing fluids. Thus, the accuracy of evaluation results is influenced. In this paper, tight sandstone cores of the Lower Jurassic Ahe Formation(J1 a) in Dibei area of Kuqa Depression of the Tarim basin were selected as samples. The invading process of fracturing fluid into a tight sandstone reservoir was simulated by modifying experimental process and method. Then, the damage degree of fracturing fluid to gas reservoir was evaluated and the damage mechanisms of fracturing fluid were analyzed systematically. And the following research results were obtained. First, the modified evaluation method takes into account the influences of several factors, such as the original water saturation of gas reservoir, the instantaneous "breakdown" effect of high pressure during fracturing and the fracturing fluid residue, so it can evaluate the damage degree of fracturing fluid to tight sandstone gas reservoirs more objectively. Second, the evaluation results based on the industry standard show that the damage degree of fracturing fluid to the permeability of tight sandstone gas reservoirs is medium to strong, whereas the damage degree evaluated by the modified method is medium to weak. Third, the retention of fracturing fluid residue in fractures is the main cause of permeability damage. The residues can easily block fractures and fracture surface pores. Most of them retain in the

关 键 词：致密砂岩气层 压裂液 损害机理 基质 评价方法 高压“击穿” 《水基压裂液性能评价方法:SY/T 5107-2016》 

分 类 号：TE377[石油与天然气工程—油气田开发工程]