Abstract: Multiple sets of strike-slip faults are developed in the central-western Yuqi area of the Akkule uplift in Tarim Basin, exhibiting complex fault characteristics and serious reservoir filling. It is essential to clarify the geometric and kinematic features, genetic mechanisms, and reservoir control effects of strike-slip faults in this area. This study focuses on multiple groups of strike-slip faults. Using fine-scale analysis techniques for small and medium-sized faults, a detailed investigation was performed on the fault orientation, density, extension length, vertical pattern, slip direction, activity intensity and phases, and genetic mechanisms. Combined with actual drilling data, the reservoir control effects of these faults were elucidated. The findings indicate that four groups of strike-slip faults are developed in the Ordovician System of the central-western Yuqi area. Among these, the dominant NNE-striking fault was formed by the coalescence of the NNE-striking segments of conjugate faults from the Tahe area and the secondary faults derived from Luntai fault. As the intermediate principal stress (σ₂) increases with depth, the NNE-striking fault develops downward, exhibiting multiple stages of inherited activity. As influenced by the basement tectonic activity of pre-existing structures and the gradual variations in σ₂, the NE-striking faults display lateral connection features at the top boundary of the Middle Cambrian system. The NEE-striking fault undergoes slow left-lateral slip due to low stress, forming a braided structure composed of Riedel shear fractures (R) and secondary co-trending shear fractures (P), which is consistent with Riedel’s left-lateral shear model. The SN-striking fault formed during the Middle to Late Hercynian period, and subsequently truncated both the NNE- and NE-striking faults. All these three faults exhibit left-lateral strike-slip characteristics. During the Middle-Late Hercynian to Indosinian period, the faults experienced a shift in their slip direction and remained active until the Himalayan period. The central-western Yuqi area primarily develops fracture- and cave-type reservoirs. The development degree of the fracture-type reservoirs shows an exponential negative correlation with the distance from the well to the faults. Strike-slip faults provide favorable conduits for corrosive fluids, facilitating the formation of cave-type reservoirs. Strong bead-like anomalies are observed in seismic profiles in the proximity of strike-slip faults with intense late-stage activity and high fluid connectivity, where both fracture- and cave-type reservoirs are more developed. These areas represent favorable targets for further exploration.

Key words: strike-slip fault, central-western Yuqi area, Akekule uplift, genesis mechanism, fault-controlled reservoir

摘要： 塔里木盆地阿克库勒凸起于奇中西部地区发育多组走向的走滑断裂,断裂特征复杂,储层充填严重。明确该地区走滑断裂的几何学与运动学特征、成因机制及控储作用十分必要。以多组走滑断裂为研究对象,依据中—小尺度走滑断裂精细解析技术,对断裂的走向、密度、延伸长度、垂向样式、滑移方向、活动强度与期次以及形成机制开展了精细解析,并结合钻井实测资料明确了断裂的控储作用。研究结果表明,于奇中西部地区奥陶系主要发育4组走向断裂,其中,NNE向断裂是其主要断裂,由塔河主体区共轭断裂向NNE向的延伸段与轮台断裂派生的次级断裂拼接而成。因中间主应力(σ₂)随深度增加而变大,NNE向断裂呈自上而下发育,形成多期继承性活动。由于先存构造的基底构造作用及σ₂变化,NE向断裂在中寒武统顶界深度处表现为侧接特征。NEE向断裂因所受的应力作用较小而发生缓慢左行滑移,由里德尔剪切破裂和次级同向剪切破裂构成"辫状"特征,符合里德尔左行剪切模型。中—晚海西期SN向断裂形成,同时切割了NNE向与NE向断裂,三者皆为左行走滑断裂。从中—晚海西期至印支期,断裂滑移方向发生转变并持续活动至喜马拉雅期。于奇中西部地区主要发育裂缝型和洞穴型2类储集体,其中,裂缝型储集体的发育程度与钻井到断裂的距离呈指数型负相关。走滑断裂为溶蚀流体提供了通道,有利于洞穴型储集体发育。在晚期活动强、通源性好的走滑断裂附近,地震剖面呈现强串珠异常,有效裂缝型和洞穴型储集体均更加发育,是下一步勘探的有利目标。

关键词: 走滑断裂, 于奇中西部地区, 阿克库勒凸起, 成因机制, 断裂控储