摘要
玛南斜坡上乌尔禾组致密砾岩储集层岩相复杂,非均质性强,水力压裂裂缝扩展形态复杂,压裂设计优化缺乏理论依据。以玛南斜坡上乌尔禾组颗粒支撑砾岩为研究对象,通过纳米压痕实验,分别测定了砾石和基质的岩石力学性质。在此基础上,开展水力压裂实验,明确了不同压裂液下的裂缝扩展形态和压力曲线特征。研究结果表明:纳米尺度下,砾石受载后为弹塑性变形,基质为塑性变形,砾石的弹性模量、硬度、断裂韧性和储存的弹性能比例均高于基质;在砾石和基质较大的力学性质差异下,颗粒支撑砾岩裂缝扩展受砾石主导,绕砾延伸是主要的裂缝扩展形式;滑溜水压裂在井筒处趋于多点起裂,形成辐射状多裂缝扩展形态;胍胶压裂趋于形成迂曲双翼垂直缝,但裂缝遇砾石易分支,形成水平缝和垂直缝相互沟通的迂曲裂缝;井底压力曲线未见明显破裂压力,但胍胶压裂的延伸压力较滑溜水高且波动更加剧烈。
The tight conglomerate reservoirs with complicated lithofacies in the Wuerhe formation on the Manan slope are strongly heteroge⁃neous,resulting in complicated fracture shapes after hydraulic fracturing,and insufficient theoretical basis for optimizing fracturing design.Taking the gravel⁃supported conglomerate as a research object,the mechanical properties of the gravel and the matrix were measured through nanoindentation experiments,and then hydraulic fracturing experiments were carried out to characterize the hydraulic fracture propagation and pressure curves after injecting different fracturing fluids.The research results show that,on a nanometer scale,the gravel underwent elastoplastic deformation,while the matrix underwent plastic deformation after injecting fracturing fluid;the elastic modulus,hardness,fracture toughness and stored elastic energy of the gravel are all higher than those of the matrix.With a wide gap in mechanical properties between gravel and matrix,the fracture propagation in the gravel⁃supported conglomerate is mainly controlled by gravel,and the extension around gravel is the main form of fracture propagation.Slick⁃water fracturing tends to initiate fractures at multiple points near wellbore,forming a radial propagation of multiple fractures.Guar⁃gum fracturing tends to induce tortuous double⁃wing vertical fractures,but the fractures are easy to branch when encountering gravels,forming tortuous fractures with horizontal and vertical branches communi⁃cating with each other.There is no obvious fracture initiating pressure on the bottom⁃hole pressure curve,but the extension pressure of guar⁃gum fracturing is higher and more fluctuant than that of slick⁃water fracturing.
作者
俞天喜
袁峰
周培尧
郝丽华
邹雨时
马新仿
张兆鹏
YU Tianxi;YUAN Feng;ZHOU Peiyao;HAO Lihua;ZOU Yushi;MA Xinfang;ZHANG Zhaopeng(Research Institute of Engineering Technology,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang 834000,China;State Key Laboratory of Petroleum Resources and Exploration,China University of Petroleum,Beijing 102249,China)
出处
《新疆石油地质》
CAS
CSCD
北大核心
2021年第1期53-62,共10页
Xinjiang Petroleum Geology
基金
国家自然科学基金(51974332)。
关键词
玛湖凹陷
上乌尔禾组
致密砾岩储集层
水力压裂实验
岩石力学性质
裂缝扩展形态
压力曲线
Mahu sag
upper Wuerhe formation
tight conglomerate reservoir
hydraulic fracturing experiment
rock mechanical property
fracture propagating shape
pressure curve
