基于径向井压裂复合降压法的天然气水合物开采产能数值模拟  

Numerical simulation of natural gas hydrate productivity based on radial well fracturing combined with the depressurization method

作　　者：惠程玉 张逸群 张潘潘 武晓亚 李根生[1] 黄浩宸 HUI Chengyu;ZHANG Yiqun;ZHANG Panpan;WU Xiaoya;LI Gensheng;HUANG Haochen(State Key Laboratory of Petroleum Resources and Prospecting//China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]“油气资源与探测”国家重点实验室·中国石油大学(北京)

出　　处：《天然气工业》2022年第12期152-164,共13页Natural Gas Industry

基　　金：国家自然科学基金面上项目“天然气水合物井底径向空化射流增产机理与调控方法研究”(编号:52174009);广东省海洋经济发展(海洋六大产业)专项资金项目“天然气水合物储层改造增产与测试技术支撑”(编号:GDNRC[2022]44);中国石油大学(北京)基本科研业务费项目“天然气水合物多簇压裂增产机理研究”(编号:ZX20220047)。

摘　　要：压裂是提高天然气水合物(以下简称水合物)开采效率的潜在方法之一,但当前在径向井压裂降压开采水合物时,径向井分支数与裂缝参数对水合物压裂后产能的影响规律研究相对较少,水合物增产缺乏理论基础。为此,基于开源程序HydrateResSim对具有渗透性边界的第三类水合物藏储层进行了径向井压裂复合降压法开采水合物产能模拟,对比了不同位置、数量的裂缝及不同径向井分支数影响下开采过程中压力场、温度场、水合物饱和度、甲烷饱和度分布及产能变化,并分析了水合物的增产规律。研究结果表明:①裂缝在水合物储层中构建了高导流能力通道,显著降低了近井区域渗流阻力,提高了压力降传播速度,扩大了水合物分解范围;②压裂裂缝距离主井筒越近,开采初期压力降传播效果越好;③裂缝总缝长相等时,增加裂缝数量有利于提高产能;④径向井分支数增加,产气速率及生产气水比均有明显提高。结论认为,径向井压裂复合降压法可以提高水合物开采效率,是一种实现水合物商业化开采的潜在新方法,将有助于推进我国南海水合物产业化进程,研究结果对于南海天然气水合物的实地化开采具有重要的指导意义。Fracturing is one of the potential methods to improve the exploitation efficiency of natural gas hydrate(hereinafter referred to as hydrate).At present,however,when the radial well fracturing and depressurization method is used for hydrate exploitation,the influence of number of branches of radial well and fracturing parameters on the hydrate productivity after fracturing is less researched,and there is no theoretical basis for hydrate stimulation.In this paper,the simulation of hydrate productivity exploited by radial well fracturing combined with depressurization method is performed on the third type of hydrate reservoir with permeable boundary based on the open source program HydrateResSim.In addition,the change of pressure field,temperature field,hydrate saturation,methane saturation distribution and productivity in the process of hydrate exploitation at different fracture positions,number of fractures and number of branches of radial well are compared,and the hydrate stimulation laws are analyzed.And the following research results are obtained.First,fractures construct channels of high flow conductivity in hydrate reservoirs,so as to greatly decrease the flow resistance near the wellbore,increase the pressure drop propagation speed and enlarge the hydrate dissociation range.Second,the closer the hydraulic fracture is to the main hole,the better the pressure drop propagation effect in the initial exploitation stage is.Third,when the total fracture length is the same,the productivity can be improved by increasing the number of fractures.Fourth,as the number of branches of radial well increases,the gas production rate and the production gas/water ratio increase significantly.In conclusion,the radial well fracturing combined with depressurization method can improve hydrate exploitation efficiency,and it is a potential new method to realize commercial hydrate exploitation,which is conducive to promote the industrialization process of hydrate in the South China Sea.The research results are of great guiding signifi

关 键 词：天然气水合物 神狐海域 径向井 水力压裂 降压法 增产规律 数值模拟 裂缝 开采效率 

分 类 号：TE53[石油与天然气工程—油气田开发工程]