塔里木盆地走滑带碳酸盐岩断裂相特征及其与油气关系

通过露头与井下资料的综合分析,塔里木盆地奥陶系碳酸盐岩走滑断裂带断裂相具有多样性,根据内部构造发育程度可以分为断层核发育、断层核欠发育两类。露头走滑带断层核部以裂缝带、透镜体、滑动面等断裂相发育为特征,断裂边缘的破碎带发育裂缝带、变形带。裂缝带主要分布在断层核附近50m的破碎带内,裂缝多开启,渗流性好。断裂核部透镜体发育,在破碎带也有分布,破碎角砾组合的透镜体多致密。滑动面具有平直截切型、渐变条带型等两种类型,多为开启的半充填活动面。变形带多为方解石与碎裂岩充填,破碎带局部部位裂缝与溶蚀作用较发育。利用地震剖面、构造图、相干图等资料可以判识塔里木盆地内部奥陶系碳酸盐岩走滑断裂相的特征及其发育程度,沿走滑断裂带走向上断裂相具有分段性与差异性,根据渗流性可以定性区分高渗透相、致密相区。沿断裂带高渗透相区是碳酸盐岩缝洞体储层发育的有利部位。断裂相的横向变化造成油气分布的区段性,形成高渗透相输导模式、致密相遮挡模式等两类成藏模式。走滑断裂带碳酸盐岩断裂相的特征及其控藏作用对油气勘探开发储层建模具有重要意义。

The Characteristics of the Strik-Slip Fault Facies and its relations to hydrocarbon in Ordovician Carbonate, Tarim basin

Integrated analyses of the Ordovician carbonate outcrops and downhole data in the Tarim basin show that the strik-slip fault facies of the Ordovician carbonatic rock is of large variety. Based on the development degree of internal structures, faulting can be divided into two types: well-developed fault core and undeveloped fault core. In the outcrops, the fault core of strike-slip zone is characterized by fracture zones, lens and slip surfaces, with fissure and deformed zones developed within damage bands at the margin of fault. Fractures zones are distributed mainly in damage zone, about 50 m far from the faulting core, with well-developed open fractures and good infiltration. Lenses are well developed within the faulting core, as well as in damage zones. And most lenses are compact with low porosity and permeability. Slip surfaces contain straight intercept type and gradation band type, and most are open surface filled partially. Deformation belts are mostly filled with calcite and cataclasite, with fractures and dissolution vugs developed locally in damage zones. Using seismic profiles, structural map and coherence data, I can be identified the characteristics and development degree of strike-slip fault facies in Ordovician carbonate. The fault facies is characteristic of segmentation and differentiation along the trending of strike-slip faults, which can be used to identify high permeability facies and compact permeability facies. The high permeability areas along faulting zone are favorable for development of fracture-caves within carbonate reservoir. The segmentation of hydrocarbon distribution, caused by the horizontal change of strike-slip fault facies, formed the high permeability transporting model and the tight barrier model of hydrocarbon accumulation. The characteristics of strike-slip fault facies and their control over the pools are of great significance for carbonate reservoir modeling exploration and development.