Experimental modeling of sanding fracturing and conductivity of propped fractures in conglomerate:A case study of tight conglomerate of Mahu sag in Junggar Basin,NW China  

作　　者：ZOU Yushi SHI Shanzhi ZHANG Shicheng YU Tianxi TIAN Gang MA Xinfang ZHANG Zhaopeng 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249,China [2]Engineering Technology Research Institute,PetroChina Xinjiang Oilfield Company,Karamay 834000,China

出　　处：《Petroleum Exploration and Development》2021年第6期1383-1392,共10页石油勘探与开发（英文版）

基　　金：Supported by the PetroChina-China University of Petroleum(Beijing)Strategic Cooperation Project(ZLZX2020-04)。

摘　　要：True tri-axial sanding fracturing experiments are carried out on conglomerate samples from the Permian Wuerhe Formation of Mahu sag,Junggar Basin,to study hydraulic fracture propagation geometry and quartz sand transport in ma-trix-supported fine conglomerate and grain-supported medium conglomerate.The effect of rough fracture surface on conduc-tivity is analyzed using the 3D-printing technology to reconstruct the rough surface formed in the fractured conglomerate.The hydraulic fractures formed in the matrix-supported fine conglomerate are fairly straight,and only more tortuous when en-countering large gravels at local parts;thus,proppants can get into the fractures easily with transport distance about 70%–90%of the fracture length.By contrast,in the grain-supported medium conglomerate,hydraulic fractures tend to bypass the gravels to propagate in tortuous paths and frequently change in width;therefore,proppants are difficult to transport in these fractures and only move less than 30%of the fracture length.As the ma trix-supported fine conglomerate has high matrix content and low hardness,proppants embed in the fracture surface severely.In contrast,the grain-supported medium conglomerate has higher gravel content and hardness,so the quartz sand is crushed more severely.Under the high proppant concentration of 5 kg/m^(2),when the closure stress is increased(above 60 MPa),fractures formed in both matrix-supported fine conglomerate and grain-supported medium conglomerate decrease in width significantly,and drop 88%and 92%in conductivity respectively compared with the case under the low closure stress of 20 MPa.The field tests prove that under high closure stress above 60 MPa,using a high proportion of fine proppants with high concentration allow the proppant to move further in the fracture;meanwhile proppant places more uniformly in the ro ugh fracture,resulting in a higher fracture conductivity and an improved well per-formance.

关 键 词：matrix-supported fine conglomerate grain-supported medium conglomerate sand fracturing fracture propaga-tion proppant transport fracture conductivity 

分 类 号：TE34[石油与天然气工程—油气田开发工程]