基于测井资料的辫状河三角洲沉积储层精细描述

Detailed description of the sedimentary reservoir of a braided delta based on well logs

通过岩心观察、常规测井和成像测井等资料,对库车坳陷大北克深地区白垩系巴什基奇克组辫状河三角洲沉积储层特征进行了精细研究。结果表明辫状河三角洲前缘发育的水下分流河道、河口坝等构成了主要的骨架砂体类型。通过岩心刻度测井建立了一套较完整的岩性和沉积构造识别模式。在此基础上建立了不同沉积微相的测井识别与划分标准,并探讨了不同沉积微相对储层物性的控制。然后根据粒度中值和成分成熟度指数将沉积微相进一步细分为水下分流河道中砂岩、水下分流河道细砂岩等不同的岩性岩相类型,并分别建立了粒度中值和成分成熟度指数的测井评价模型。在此基础上以成像测井为主,辅以常规测井和岩心资料及粒度参数和成分成熟度指数,实现单井连续的岩性岩相识别与划分。研究成果可为后续沉积储层精细评价乃至天然气勘探开发综合研究奠定基础。

The sedimentary reservoir of Lower Cretaceous Bashijiqike Formation in Kuqa depression was studied by making full use of core observation as well as conventional and image logs. The results show that the Bashijiqike Formation was formed in the sedimentary facies zone of braided delta front subfacies, of which the underwater distributary channel and mouth bar depositional microfacies constitute the main framework of sandbodies. A suite of recognition models for typical lithologies and sedimentary structures were built by core-log calibration methods. Then the well logging recognition and division standards were built, and the control of depositional microfacies on reservoir quality was discussed. The depositional microfacies were further divided into lithologies and lithofacies such as medium-grained sandstones of underwater distributary channel and fine-grained sandstones of underwater distributary channel based on the medium grain size and compositional maturity index. In addition, the logging evaluation methods of medium grain size and compositional maturity index were built. At last, the vertical distribution law of lithologies and lithofacies in single wells were figured out by making full use of image logs, shapes of conventional logs and core observations as well as the logging calculation of medium grain size and compositional maturity index. The research results lay a solid foundation for detailed description of sedimentary reservoir as well as the natural gas exploration and development in the future.