歧口凹陷低电阻率油气层分布规律研究

Distribution law of low-resistivity oil and gas layers in Qikou Sag.

歧口凹陷低电阻率油气层广泛存在、成因复杂、测井评价难度大,明确低电阻率油气层分布规律对成功识别低电阻率油气层意义重大。从大量基础岩石物理数据出发,通过分析不同层位、不同埋藏深度的低电阻率油气层与储集层孔隙度、渗透率、岩石孔径、泥质含量、黏土矿物含量及沉积环境之间的关系,明确了由沉积内因引起的低电阻率油气层基本分布在主力相带边缘,通常发育在岩性细、泥质含量较重、孔隙结构较差、微孔隙发育的储集层。明化镇组、馆陶组、东营组泥质含量和黏土矿物类型对低电阻率油气层控制作用相对明显,沙河街组孔隙结构差异对低电阻率油气层控制作用相对明显,而钻井液侵入型低电阻率油气层往往与高矿化度钻井液钻井工艺相伴生。分析研究不同成因类型低电阻率油气层分布规律,为准确识别低电阻率油气层提供了可靠依据。

Low-resistivity oil and gas layers in Qikou Sag is widespread,the causes are complicated, well logging evaluation is difficult.To clear the distribution law of low-resistivity oil and gas layers is significant for successful identification of low-resistivity oil and gas layers.Setting out from a large number of basic petrophysical data,the authors analyzed the relationship between low-resistivity oil and gas layers of the different horizons,burial depth,reservoir porosity, permeability,rock aperture,clay content,clay mineral content and depositional environment,cleared that the low -resistivity oil and gas layers were formed by the internal causes of deposition and mainly distributed at the edge of major facies belt and usually developed in the reservoirs of fine lithology, heavier clay content,poor pore structure and well developed micro-pore.The shale content and types of clay mineral in Minghuazhen Formation, Guantao Formation and Dongying Formation have a relatively obvious control role on the low-resistivity oil and gas layers,the pore structure differences in Shahejie Formation has a relatively obvious role for the low-resistivity oil and gas layers,while the low-resistivity oil and gas layers of drilling fluid invasion type is often accompanied with brine drilling fluid.The paper analyzed the distribution law of different genetic types of low-resistivity oil and gas layers and provided a reliable basis for accurate identification of low-resistivity oil and gas layers.