酒东坳陷下白垩统砂岩中碳酸盐胶结物特征与储层物性

碳酸盐胶结物是酒东坳陷下白垩统砂岩内一种重要的自生矿物,其对深部储层储层质量有着重要影响。本文通过薄片观察、扫描电镜、能谱分析及碳氧同位素分析,认为碳酸盐胶结物主要为铁方解石、白云石和铁白云石,并且以后者为主,其分布具有不均一性且分带性明显。碳酸盐胶结物均为成岩作用后期产生,形成该矿物所需的物质主要来源于泥岩的黏土矿物...

Characteristics of Carbonate Cements and Reservoir Quality of the Lower Cretaceous Sandstone in Jiudong Sag

 The deep burial sandstone reservoir quality is seriously affected by the carbonate cements which is an essential autogenic mineral in the Lower Crataceous formation in Jiudong sag. The thin sections and scanning electron microscope are analyzed, the energy spectroscopy ,carbon and oxygen isotopes of carbonate cements are tested. The study results indicate that the carbonate cements of Lower Crataceous sandstone from the Jiudong sag are mainly ferrous dolomite, ferrous calcite and dolomite with heterogeneous distribution and apparent zonation. They were formed in the late stage of diagenesis and the source are mainly derived from clay minerals transformation, thermal evolution of organic matter in the mudstone and the part of the calcium from the alteration of plagioclase. The key reason for development of the high quality reservoir in the deep burial low permeability reservoirs is the dissolution of carbonate cements. In addition, the content of carbonate cement also have an impact on reservoir quality, if the content is greater than 5%,  with the increase  of  the content of carbonate cements the porosity decreases, while it's less than 5%,  there  is  no  obvious  correlation between porosity and carbonate cement content.