准噶尔盆地大有3井区井井子沟组储层水敏机理分析

Water Sensitivity Mechanism of P_2jj Formation Reservoir in Dayou-3 Well Block, Junggar Basin

摘要: 针对准噶尔盆地大有3井区井井子沟组储层非均质强、具有潜在水敏性及压裂开发整体产油效果不佳的问题，弄清该区块储层水敏作用机理为选择合适工作液提供指导显得尤为重要。本文开展水岩作用实验、岩石力学特性分析，根据水岩作用垮塌程度将岩样分为三类：不垮塌(I类)、缓速垮塌(II类)和快速垮塌(III类)，II类和III类岩样均属于软岩范畴。针对三类典型岩样开展了岩样矿物组成及含量分析、岩样微观结构分析及可溶盐分析等，实验结果表明：(1) 黏土矿物总含量高(伊蒙混层含量高，且蒙脱石占比高)是引起水敏的根本；(2) 胶结疏松、以粒间溶孔为主或构造缝发育、填隙物中(铁)泥质含量高且可溶盐含量高等与岩样垮塌程度呈正相关，对于III类岩样快速崩解分析认为是多重因素耦合作用造成。

Abstract: For the problems of strong heterogeneity, potential water sensitivity and poor overall oil production effect of fracturing development in the formation in Dayou-3 well block of Junggar basin, it is particularly important to clarify the reservoir water sensitivity mechanism in this block to provide guidance for selecting appropriate working fluid. In this paper, laboratory experiment of water-rock interaction and analysis of rock mechanical property were carried out. According to the collapse degree of water rock interaction, the rock samples are divided into three categories: not collapsed (Class I), slowly collapsed (Class II) and rapidly collapsed (Class III). Both Class II and Class III rock samples belong to the category of soft rock. Through the analysis of mineral composition and content, microstructure and soluble salt of rock samples for three types of typical rock samples, the experimental results show that (1) The high total content of clay minerals (high content of montmorillonite mixed layer and high proportion of montmorillonite) is the fundamental cause of water sensitivity; (2) The degree of rock collapse is positively correlated with loose cementation, mainly intergranular dissolved pores or developed structural fractures, high content of (iron) mud and soluble salts in the filling material. For the rapid disintegration analysis of Class III rock samples, it is believed to be caused by the coupling effect of multiple factors.