基于CDEM的天然气水合物沉积物水力压裂裂纹扩展数值模拟  

Numerical simulation of hydraulic fracture characteristics in gas hydrate bearing-sediments by using CDEM

作　　者：黄宇东 王天驹 王蕊 王昊天 鲁晓兵 张旭辉 Yudong Huang;Tianju Wang;Rui Wang;Haotian Wang;Xiaobing Lu;Xuhui Zhang(Institutes of Mechanics,Chinese Academy of Sciences,Beijing,100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing,100049,China;CPOE Research Institute of Engineering Technology,Tianjin,300450,China;CNPC Offshore Engineering Company Limited,Beijing,100176,China)

机构地区：[1]Institutes of Mechanics,Chinese Academy of Sciences,Beijing,100190,China [2]School of Engineering Science,University of Chinese Academy of Sciences,Beijing,100049,China [3]CPOE Research Institute of Engineering Technology,Tianjin,300450,China [4]CNPC Offshore Engineering Company Limited,Beijing,100176,China

出　　处：《Acta Mechanica Sinica》2024年第2期28-38,共11页力学学报（英文版）

基　　金：the National Natural Science Foundation of China(Grant No.12072347);the Excellent Training Plan of the Institute of Mechanics,Chinese Academy of Sciences,and CNPC New Energy Key Project(Grant No.2021DJ4902).

摘　　要：目前,天然气水合物开采存在储层渗透率低和热传导导致生产效率低等问题.作为一种常规油气勘探中有效提高储层渗透率的技术,水力压裂有望用于改善天然气水合物储层的渗透率,提高采收效率.然而,有关含天然气水合物沉积物(GHBS)水力压裂应用的研究却很少.本文采用有限元和离散元耦合的连续离散元法(CDEM),对不同地层性质的天然气水合物沉积物(GHBS)的水力压裂过程进行了二维的数值模拟,研究了储层性质和压裂参数对GHBS中裂缝生成的影响.主要结论是,在本研究考虑的压裂参数和沉积物性质中,内摩擦角越小、注入流量越大对产生裂缝越有利;当饱和度和黏聚力处于适当范围时,最有利于产生裂缝;当各方向的地应力相等时,最有利于压裂产生裂缝,但最不利于主要裂缝向更远的方向延伸.Currently,gas hydrate exploitation suffers from problems such as low efficiency of production due to the low permeability of the reservoir and thermal conduction.As an effective technique for enhancing reservoir permeability in conventional oil and gas exploration,hydraulic fracturing is expected to be applicable for improving the permeability of natural gas hydrate reservoirs and increasing recovery efficiency.However,the research on the application of hydraulic fracturing of gas hydrate-bearing sediments(GHBS)is few.In this paper,the continuous-discontinuous element method(CDEM),which couples finite and discrete elements,is used to numerically simulate the hydraulic fracturing process in GHBS with different formation properties in a two-dimensional situation.The effect of reservoir properties and fracturing parameters on fracture generation in GHBS is investigated.The main conclusions are that among the fracturing parameters and sediment properties considered in this study,the smaller angle of internal friction angle and the higher injection flow rate are positive for fracturing.It is the most favorable condition for fracturing when the saturation and cohesion are in an appropriate range.The condition,when geostatic stress is equal in all directions,is the most favorable for fracturing but the least favorable for fracturing to extend farther.

关 键 词：含天然气水合物沉积物 水力压裂 离散元法 地层性质 水合物储层 天然气水合物开采 内摩擦角 裂纹扩展 

分 类 号：P61[天文地球—矿床学]