东海海域深层HG组低渗储层“甜点”预测方法及应用

“Sweet Spot” prediction and its application in the low permeability reservoir of the deep HG formation in the East China Sea

东海深层HG组目的层埋藏深(>3 500 m),储层具有低孔低渗特征,但局部发育“甜点”储层。由于“甜点”储层界限模糊,且与差储层及致密层地球物理响应差异小,因而预测难度大。为此,首先从井出发,在“甜点”储层主控因素分析的基础上,结合动态分析测试成果,建立分类储层综合评价标准,定义“甜点”储层界限;然后开展分类储层岩石物理分析,研究储层岩相及“甜点”储层弹性参数敏感性,通过叠前同时反演确定储层岩相及优质储层展布;最后,采用叠前AVO敏感属性流体检测技术预测含气富集区带,有效刻画“甜点”储层展布。实际应用结果表明,这种方法极大提高了研究区“甜点”储层预测的精度,为落实分级储量规模、部署开发井位和优化调整方案提供了科学的地质依据,在相似气田开发中有一定的借鉴意义。

Although the deep HG formation in the East China Sea is deeply buried,and the reservoir exhibits low porosity and permeability,“sweet spots”have developed locally.The key to oil and gas exploration and development is to find high quality“sweet spot”reservoirs.Because of the small differences in the physical response between“sweet spot”reservoirs and bad reservoirs or tight layers,it is difficult to predict“sweet spot”reservoirs using seismic data.To effectively depict the distribution of“sweet spot”reservoirs,“sweet spot”prediction technology has been developed based on geophysics.First,the controlling factors analysis of the“sweet spot”reservoir combined with the dynamic analysis of the test results is used to establish the evaluation standard of the reservoir,thereby determining the definition of the“sweet spot.”the evaluation standard for reservoirs is established based on factors controlling“sweet spot”reservoirs and a dynamic analysis of the test results.The definition of a“sweet spot”reservoir is determined.Then sensitive elastic parameters used to identify litho-facies and“sweet spots”are extracted using petro-physics analysis.Reservoir litho-facies and good reservoir distributions can be predicted by simultaneous inversion using pre-stack gathers,and gas enrichment zones can be predicted using pre-stack AVO technology.Finally,“sweet spot”reservoirs can be revealed by the combination of inversion results and the recognition of gas.The exploration and production application demonstrated that this method was able to achieve favorable results in the prediction of the low permeability“sweet spot”sandstone reservoirs in the deep Huagang Formation in the sea and can thus provide a reference for other tight sand“sweet spot”reservoir predictions.