田冷,肖聪,刘明进,顾岱鸿
TIAN Leng,XIAO Cong,LIU Mingjin,GU Daihong

• 1:中国石油大学石油工程学院
• 2:西南石油大学地球科学与技术学院

摘要(Abstract)：

页岩气是典型的非常规油气藏,需借助水平井压裂技术形成高导流人工裂缝进行开发。由于支撑剂的沉降作用,人工裂缝渗透率存在各向异性;同时,近井筒附近气体的汇集作用以及水平井筒偏心所引起较大的压降对页岩气产能的影响也不容忽略。传统的三维隐式差分法,一方面需要结合其他时刻的产能数据,另一方面需要对整个三维空间进行网格离散而变得异常复杂,而且时间步长的取值对其精度影响也较大。在三孔块状模型基础上,建立了考虑页岩气解吸、扩散、人工裂缝各向异性和井筒表皮影响的页岩气产能模型。利用拉普拉斯变换,将空间三维转化为平面二维问题,消除时间变量影响,结合隐式差分法,获得拉普拉斯空间解,最后运用Stehfest数值反演获得产能数值解,并对各种产能影响因素进行分析。该方法对页岩气开发具有一定指导意义。
Shale gas is one of the typical unconventional petroleum reservoirs,it is necessary to take advantage of horizontal well fracturing technique to develop them by the high-conductivity fractures.Due to the sedimentation of the proppants,there are the anisotropy in the artificial fractures;the converge of the gas near the wellbore and eccentric action of horizontal wellbore can cause a great pressure drop on the shale gas productivity,this influences can't be neglected.In terms of the traditional 3D implicit difference methods,on the one hand,the other time' s productivity data are needed;on the other hand,it is necessary to disperse the whole 3D space and this process is very complex,the value seeking of the time step has a great influence on the accuracy.Based on the tertiary-porosity blocky model,the shale-gas productivity model is established considering the desorption,diffusion,anisotropy of the artificial fractures and skin effects of the wellbore.By Laplace transform,the 3D-space problems in are transformed into 2D ones,the impacts of the time variants can be eliminated,integrating with the implicit difference method,the Laplace spatial solution is obtained,by Stehfest numerical inversion,the productivity numerical solution is presented,all the influencing factors on the productivity are analyzed.The method possesses a certain guiding significance in the development of the shale gas.

关键词(KeyWords)： 页岩气;水平井;体积压裂;各向异性;解吸;扩散;影响因素;产能预测
shale gas;horizontal well;volumetric fracturing/frac;anisotropy;desorption;diffusion;influencing factor;productivity prediction

Abstract:

Keywords:

基金项目(Foundation): 国家自然科学基金项目(51204193)资助

作者(Author): 田冷,肖聪,刘明进,顾岱鸿
TIAN Leng,XIAO Cong,LIU Mingjin,GU Daihong

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