垦利A油田辫状河三角洲前缘优质储层特征

Characteristics of High-quality Reservoirs in the Braided River Delta in Kenli-A Oilfield

明确渤海湾盆地莱州湾凹陷垦利A 油田古近系沙三上段优质储层特征及成因,可为凹陷内油气勘探提供依据。结合钻井、测井等资料,利用扫描电镜、铸体薄片、孔渗物性、流体包裹体等多种分析测试手段,开展构造沉积背景、埋藏史、地层温压系统等相关研究。结果表明,沙三上段储层具“高孔高渗”特征,储集空间以粒间孔为主,微裂缝较发育,孔喉以大中孔中细喉为主;储层成岩作用总体处于中成岩A 期,表现为“中压实、强溶蚀、弱胶结”的特征,优质储层的形成主要受构造背景、沉积环境、成岩作用和地层超压等4 方面的影响。莱州湾凹陷南部斜坡带的储层发育具有分带性,重力滑脱断层(F1)内侧优质储层发育,是油气成藏的有利地区。

A clear understanding of the characteristics and genesis of high-quality reservoirs in Kenli A Oilfield in the Laizhou Bay Sag of the Bohai Bay Basin in Upper E s3 of the Paleogene Shahejie Formation can provide a foundation for oil and gas exploration in the depression. Combining data from drilling, logging, thin section casting, scanning electron microscopy, physical properties, fluid inclusions, and other analytical testing methods, the regional tectonic background, burial history, and sedimentary systems were investigated. The upper reservoir of the Shahejie Formation exhibited characteristics of “high porosity and high permeability” and the reservoir space was shown to be dominated by intergranular pores with relatively well- developed micro-cracks. The pore throat can be classified as large-medium or medium-small throat. The reservoir diagenetic effect is generally observed in middle diagenetic stage A, which is characterized by “medium compaction, strong dissolution, and weak cementation”. The formation of high-quality reservoirs is affected by four main aspects: Tectonic setting, sedimentary environment, diagenesis, and overpressure of the formation. Reservoir development in the southern slope of the Laizhou Bay Sag is zonal, where high-quality reservoirs develop on the inner side of the gravity slip fault (F1), providing a favorable area for oil and gas accumulation.