形状因子及复杂结构井拟稳态流动阶段井底压力渐近解的计算方法  

A new method for calculating shape factor and asymptotic solution of bottom hole pressure of complex-structure wells during the pseudo-steady flowing period

作　　者：徐有杰 刘启国[1] 李晓平[1] 杨思涵 张楷 谭晓华[1] XU Youjie;LIU Qiguo;LI Xiaoping;YANG Sihan;ZHANG Kai;TAN Xiaohua(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)

机构地区：[1]“油气藏地质及开发工程”国家重点实验室·西南石油大学,四川省成都市610500 [2]中国石油西南油气田公司勘探开发研究院

出　　处：《天然气工业》2021年第6期74-82,共9页Natural Gas Industry

基　　金：国家科技重大专项“深层碳酸盐岩气藏高效开发技术”(编号:2016ZX05015-003)、“低渗—致密油藏高效提高采收率新技术”(编号:2017ZX05009-004),中国石油—西南石油大学创新联合体科技合作项目“深层/超深层碳酸盐岩气田勘探开发基础理论与关键技术研究”(编号:2020CX010402),西南石油大学研究生科研创新基金项目“考虑岩石属性变化致密油气藏多段压裂水平井复杂裂缝Blasingame产量递减研究”(编号:2020cxyb046)。

摘　　要：寻求一种实用、有效的油气藏形状位置因子(以下简称形状因子)计算方法,对于准确获取复杂结构井拟稳态流动阶段井底压力渐近解及产能指数具有重要的意义。为此,针对不同形状封闭边界油气藏中的直井,根据试井分析曲线——压力及压力导数曲线之间的关系,重新计算形状因子,并且与Dietz形状因子进行对比;在此基础上,推导出复杂结构井拟稳态流动阶段井底压力渐近解并进行验证,进而绘制了Blasingame递减曲线典型图版。研究结果表明:①通过计算不同形状封闭边界直井拟稳态流动阶段无因次井底压力及压力导数,求得两者的差值,则可以反求形状因子,并且采用该方法计算的形状因子与Dietz形状因子结果非常接近,验证了该方法的准确性;②通过求取复杂结构井拟稳态流动阶段无因次井底压力及压力导数之差,可以求得复杂结构井拟稳态流动阶段井底压力渐近解系数(b_(Dpss)),进而可以获得任意复杂结构井拟稳态流动阶段井底压力渐近解;③基于新方法计算的大斜度井拟表皮因子与Ozkan等的计算结果相对误差在1%以内,验证了新方法的准确性;④对于矩形封闭边界油气藏中的常规直井,拟稳态流动阶段Blasingame递减曲线的无因次产量曲线斜率为-1,并且长宽比越大,晚期线性流特征越明显;⑤对于矩形封闭边界油气藏中压裂直井,在外边界长度一定的情况下,若长宽比越大,单井控制面积则越小,b_(Dpss)越大,晚期线性流特征越明显,Blasingame递减曲线在非稳态流动阶段所处的位置越高,而在单井控制面积相同的情况下,若无因次裂缝导流能力越大,b_(Dpss)则越小,Blasingame递减曲线在非稳态流动阶段所处的位置越高。结论认为,采用该新方法可以快速、准确地获取任意复杂结构井拟稳态流动阶段井底压力渐近解,为复杂结构井Blasingame递减曲线典型图版的绘制提供了便捷有�A practical and effective shape factor calculation method for the shape and position factor of oil and gas reservoirs(referred to as shape factor)is of great significance to calculate the asymptotic solution of bottom hole pressure and the productivity index in the pseudo-steady flowing period of complex-structure wells.For vertical wells in oil and gas reservoirs with different shapes of closed boundaries,the shape factor was recalculated on the basis of well test analysis curves(i.e.the relationship between pressure and pressure derivative curves),and then compared with the Dietz shape factor.Based on this,the asymptotic solution of bottom hole pressure of complex-structure wells during the pseudo-steady flowing period was deduced and verified,and the typical chart of Blasingame decline curves was plotted.And the following research results are obtained.First,the shape factor can be calculated reversely from the difference between dimensionless bottom hole pressure and its derivative of vertical wells during the pseudo-steady flowing period for oil and gas reservoirs with different shapes of closed boundaries.And its calculation result is quite close to the Dietz shape factor,which verifies the accuracy of this calculation method.Second,by calculating the difference between dimensionless bottom hole pressure and its derivative of complex-structure wells during the pseudo-steady flowing period,the asymptotic solution coefficient of bottom hole pressure(b_(Dpss))of complex-structure wells during the pseudo-steady flowing period can be obtained and then the asymptotic solution of bottom hole pressure of complex-structure wells during the pseudo-steady flowing period can be worked out.Third,the relative error between the pseudo skin factor of highly deviated well calculated by the new method and the calculation result by Ozkan is less than 1%,which proves the accuracy of the new method.Fourth,for the conventional vertical wells in the oil and gas reservoirs with rectangle closed boundaries,the slope of the dimension

关 键 词：油气藏形状位置因子 Dietz形状因子 拟稳态流动阶段 井底压力渐近解 拟表皮因子 压裂井 Blasingame递减曲线 

分 类 号：TE328[石油与天然气工程—油气田开发工程]