›› 2019, Vol. 40 ›› Issue (6): 1-1.doi: 10.7657/XJPG20190610

   

Analysis of Rock Mechanics and Assessments of Hydraulic Fracture Network in Conglomerate Reservoirs of Mahu Oilfield

HE Xiaodong1, MA Junxiu1, LIU Gang2, SHI Shanzhi1, YOU Jun2, WU Juntao3   

  1. (1.Research Institute of Engineering Technology, Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China; 2.Beijing Sunshine GEO-Tech Co. Ltd, Beijing 100192, China; 3.School of Petroleum Engineering, China University of Petroleum, Beijing 102249, China)
  • Online:2019-12-01 Published:2019-12-01

Abstract: Conglomerate reservoirs are characterized by tight rocks, poor cementation and strong heterogeneity, which make it difficult to analyze the complex geometry of the fractures in conglomerate reservoirs only by using geophysical well logging data or single mechanical testing method. In order to evaluate the forming capacity of hydraulic fracture network in conglomerate reservoirs, a combination of various testing methods is proposed to test the mechanical parameters of conglomerate. Taking the conglomerate reservoir of Baikouquan formation in the Well Ma-15 of the Mahu oilfield in the northwestern margin of Junggar basin as a case, the paper systematically analyzes the elasticity, compressibility, tensile property, brittleness and in-situ stress of the conglomerate reservoir and evaluates forming capacity of hydraulic fracture network. The results show that the dynamic and static elastic modulus of the reservoir are well correlated with each other, but the correlation of dynamic and static Poisson ratio is poor. The tested Biot coefficient ranges from 0.43 to 0.60, which indicates that the rock is typical of moderate-to-tight lithology. The in-situ stress in the study area is biased towards compressive strike-slip stress, and the degree of gravel cementation is low, resulting in relatively low compressive, tensile, and shear strength of the conglomerate and damages such as shear fracturing or gravel-penetrating or gravel-bypassing are easy to occur under the external loads. Planar fracture is the main form during fracturing and complex fractures form in local conglomerate formation

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