致密砂岩油藏有效厚度的确定方法——以苏北盆地阜宁组和戴一段为例

Determination and application of effective thickness of tight sandstone reservoirs:an example from Funing Formation and Daiyi Member in Subei basin

致密砂岩油藏储层的低孔低渗透特征使其不易辨别有效储层和无效储层,为了经济有效地开发致密砂岩油藏,对其有效厚度的确定进行了重新认识。针对致密砂岩油藏储层致密、物性差等特点,结合岩性、物性、含油性和电性等四性关系,以苏北盆地阜宁组和戴一段致密砂岩油藏为例,在岩心分析、试油、压汞和测井曲线等资料的基础上,运用核磁共振、经验统计和最小流动孔喉半径等5种方法确定储层物性下限及电性下限值,并相互验证。在确定的有效厚度下限标准的基础上,对研究区5口井做实际应用分析,对比见油岩心长度和测井解释有效厚度发现绝对误差为-0.15 m,层划准率为100%,此标准与实际资料吻合较好。

It is not easy to distinguish the effective and the invalid reservoir for tight sandstone reservoirs with low porosity and permeability. To develop tight sandstone reservoir economically and effectively, the effective thickness should be reconsidered. To study the characteristics of tight reservoirs with poor physical properties, we took reservoirs in the Funing Formation and Daiyi Member in Subei basin as an example. The relationship of four properties including lithology, physical property, oil-bearing property and electrical property was analyzed based on core analysis, formation testing, mercury injection, logs, etc. The lower limits of physical properties and electrical properties were studied using 5 methods, such as nuclear magnetic resonance, empirical statistics, minimum flow pore throat radius, etc. The results from different method agree with each other. Using the established lower limit standard, the effective thickness of five wells in the study area has been analyzed. The absolute error of logging interpreted effective thickness is-0.15 m by comparing with that defined by oil core. The accuracy of layer division is 100%. The proposed standard is in good agreement with the actual data and the operation is simple.