地堑式断陷盆地储层流体综合识别——以伊通盆地岔路河断陷为例

Comprehensive Liquid Identification of Hydrocarbon Reservoirs in Graben-Like Fault Basin:A Case Study in Chaluhe Depression,Yitong Basin

伊通盆地岔路河断陷古近系为地堑式断陷盆地沉积,其储层主要为重力流成因的湖泊水下扇,具有物源近、堆积速率快、岩性复杂多变的特征,加之后期成岩作用的影响,造成这类砂体物性变异系数大,非均质程度高。储层内部含流体时,流体性质难以识别,易造成测井解释上油气水层的误判。为了能够应用常规测井资料评价此类油气储层,提高测井解释的成功率,通过综合分析本区储层岩性、物性和含油气性特征,结合试油结果建立了本区岩性、物性及含油气性解释模型。岔路河断陷测井解释参数交汇图版可以明显区分出气层、油层、气水同层、油水同层、水层和干层等不同的地层油气产状。图版显示:岔路河断陷产油气储层含油饱和度下限为20%,并且产气层比产油层具有更高的深浅双侧向电阻率差值;纯水层虽然具有较好的物性条件,但含油饱和度均小于20%;干层泥质体积分数均大于22%,总孔隙度小于10.5%,物性变差,一般为无效储层。

Paleogene in Chaluhe depression,Yitong basin is graben-like fault basin sedimentary,and the reservoir is lacustrine subaqueous fan of gravity flow origin and characterized by proximal provenance,fast accumulation rate,various lithology of sandstones.Under the influence of later diagenesis,the sandstones have variable parameters in physical property,and are at a high level of heterogeneity.In order to evaluate this hydrocarbon reservoir via conventional log data,and promote the success of log interpretation,we establish a suit of interpretation model for the lithology,physical property and hydrocarbon-bearing characteristics in this region,by the method of comprehensive analysis of reservoir rock types,physical character and hydrocarbon-bearing nature,integrating with the test result of production well.The cross plots of different log interpretation parameters can remarkably distinguish gas lay,oil lay,gas and water lay,oil and water layer,water layer,and dry layer with different hydrocarbon characteristics.The cross plots indicate that oil and gas reservoirs have the limited oil saturation lower than 20% by volume,and gas-productive layers have much higher resistivity dispersion of deep-shallow dual laterolog.The pure water layers have oil saturation less than 20% by volume,although with high quality physical property.The dry layers have more than 22% muddy content by volume,causing the total porosity less than 10.5% by volume,and become the ineffective reservoirs because of the bad physical property.