川东北陆相储层裂缝特征差异性及对产能的影响

Differences of fracture characteristics and the influence on productivity in the northeastern Sichuan continental basin

川东北地区陆相储层均为致密性储层,但不同区块、层位裂缝发育的特征及对产能的影响具有差异性。选取元坝东、元坝西、马路背3个区块,综合岩心、薄片、测井、试气及试采等资料,对各区块储层裂缝发育特征、裂缝对产能的影响进行对比研究。结果表明:元坝东、元坝西部主要发育剪切缝,均以低角度裂缝为主,宏观及微观裂缝密度均较低,其中元坝东部裂缝有效性较高,元坝西区块裂缝有效性较低。马路背地区发育剪切缝、张性缝2种力学成因的裂缝,以高角度缝为主,宏观及微观裂缝密度均较高,裂缝有效性较高。宏观裂缝的倾角、有效性、密度综合影响着气井的初期产能,集中发育的网状微观裂缝或微观裂缝溶蚀作用可改善储层基质,是气井稳产的关键。

Reservoirs in the northeastern Sichuan continental basin are all tight reservoirs. However, fracture cha-racteristics and their influence on productivity are different among various areas and formations. Comparisons were made based on core, thin section, logging, gas testing and producing data collected from the eastern Yuanba, western Yuanba and Malubei blocks. The eastern and western Yuanba blocks mainly developed shearing fractures with low angle and low density. Fractures in the eastern Yuanba block are more effective than those in the western Yuanba block. The Malubei block developed both shearing and extensive fractures of mechanical geneses, with high angle, density and permeability. The angle, effectiveness and density of macro fractures controlled the produc-tivity of gas wells. A dense micro fracture network or micro fracture dissolution improves the reservoir matrix and determined if a gas well had a stable production.