储层应力敏感实验评价方法的误差分析  

Error analysis of experimental evaluation methods for stress sensitivity of reservoirs

作　　者：李乐忠[1,2] 李相方[2] 

机构地区：[1]中海石油气电集团技术研发中心 [2]中国石油大学石油工程教育部重点实验室

出　　处：《天然气工业》2013年第2期48-51,共4页Natural Gas Industry

摘　　要：目前国内外对低渗透储层岩石渗透率应力敏感性的评价方法主要是以岩心实验为主,而实验条件与实际地层条件有较大的差别。为此,运用岩石力学理论对储层上覆岩层进行力学分析,建立了储层开发过程中上覆岩石压力的计算方法,提出了储层上覆岩石压力修正系数。研究结果表明:目前关于储层上覆岩石压力的计算方法是按照流体力学的传压方式,适用于研究对象是流体或者研究区域无穷大,而实际储层之上的地层均为具有抗弯、抗剪能力的岩石,具有相互的约束力,并且气井在生产过程中压降漏斗是有限的,即上覆岩石压力是作用在限压力降区域,故而上覆岩石压力的计算公式存在较大误差,从而导致应力敏感评价误差较大;所提出的修正系数表示储层上覆岩层本身所具有的抗弯及抗剪强度,并对储层多孔介质的有效应力进行了修正;现行的实验过程中,岩石围压始终保持在一个恒定值并压在岩心上,这与实际地层情况不符,实验结果在一定程度上夸大了应力敏感的影响。The current evaluation methods at home and abroad for the stress inated by core experiments. However, there is a great difference between sensitivity of low-permeability reservoirs are mainly dom experimental conditions and actual formation conditions Therefore, the rock mechanics theory is used to make a dynamic analysis of the reservoir overlying rocks~ the calculation method is established of the overlying rocks＇ stress in the process of reservoir development~ on this basis, such a correction factor is presented. According to this study, the current calculation method of overlying rock pressure is in accordance with the fluid mechanics and is fit for studies with fluids as an objective or those with an infinite field. But in reality, those overlying rocks with mutual binding force have a high resistance to flexure and shearing strength. Moreover, the pressure conductive ability is limited in the gas well produc tion process, namely, the overlying rock pressure only affects the pressure drop in a limited area. As a result, a great error occurs in this calculation method, leading to a rather big error in the stress evaluation system. The referred correction factor indicates the re- sistance of the overlying rocks to flexure and shearing strength, with correction also to the effective stress of porous media; but in the actual experiment, the rock confining pressure is always imposed on the core at a stable value, which is inconsistent with that of the really existed bed rocks. In this respect, the experimental results exaggerate the effect of stress sensitivity to some extent.

关 键 词：储集层 上覆岩石压力 岩石围压 应力敏感 有效应力 压力修正系数 评价 观点 

分 类 号：P618.13[天文地球—矿床学]