【摘要】 一般埋深大于2 000m的中深层碎屑岩低孔渗储层除了发育高角度缝和垂直缝外,还普遍发育低角度裂缝和水平缝,从沿垂向最大应力破裂产生垂直缝和高角度缝的观点解释不通。从中深层油气藏岩体结构、岩体强度及力学稳定性角度分析,认为如果从一个油气藏单位来讲,岩体组成是均一的,则沿垂向最大主应力方向产生垂直缝或高角度缝;如果一个油气藏岩体非均质性强,存在沉积层理、岩性界面、不整合等低角度软弱结构面,岩体强度大大降低,容易受应力扰动破碎形成结构裂缝。提出了裂缝发育受三向应力差和结构面双重控制的观点,丰富和完善了裂缝成因机制,合理解释了中深层油气储层普遍发育低角度和水平缝的困扰问题,首次提出了中深层碎屑岩油气藏发育有低角度裂缝与水平裂缝的普遍性,对于建立中深层复杂裂缝预测模型具有一定的指导意义。更多还原

【Abstract】 In addition to high-angle and vertical fractures, low-porosity deep-burial reservoirs with a depth ofmore than 2,000 m are generally developed with low-angle cracks and horizontal fractures. The interpretation ofvertical fractures and high angle fractures along the vertical maximum stress fracture can’t be explained. Fromthe perspective of the rock mass structure, rock mass strength and mechanical stability of the medium and deepreservoirs, this paper considers that if the rock mass composition is uniform from a reservoir unit, a vertical frac-tures or high angle is generated along the vertical maximum principal stress direction. If a reservoir rock hasstrong heterogeneity, there are low-angle weak structural planes such as sedimentary bedding, lithologic inter-face, and unconformity, and the rock strength is greatly reduced, and it is easy to be broken by stress to formstructural cracks. This paper proposes that the development of fractures is controlled by the triaxial stress differ-ence and the structural plane. It enriches and perfects the mechanism of the formation of fractures, and reason-ably explains the dilemma of low-angle and horizontal joints commonly developed in medium and deep oil andgas reservoirs. For the first time, the universality of the low-angle cracks and horizontal cracks developed in themediumf and deep clastic reservoirs is suggested, which has certain guiding significance for the establishment ofthe model for the prediction of medium and deep complex fractures.更多还原