松辽盆地德惠断陷白垩系火石岭组凝灰岩储层预测及成藏主控因素

Prediction and main controlling factors of tuff reservoirs of Cretaceous Huoshiling Formation in Dehui fault depression,Songliao Basin

基于钻井岩心分析、测井曲线、地震等资料,运用模型正演、多参数反演体融合技术等,对松辽盆地德惠断陷白垩系火石岭组凝灰岩储层分布特征及油气富集条件进行了研究,预测了优质储层分布。研究结果表明:(1)松辽盆地德惠断陷白垩系火石岭组凝灰岩为裂隙式喷发形成的火山碎屑岩,主要为含角砾熔结凝灰岩、含角砾晶屑凝灰岩和沉凝灰岩。地震反射特征总体表现为低频、差连续、中强振幅或弱振幅,多参数反演体融合体技术预测的凝灰岩储层“甜点”分布与钻井证实结果的符合率高,凝灰岩储层平均钻遇率达92.8%,气层平均钻遇率为81.0%,其中12口井获得了工业气流;华家构造带与郭家断阶带储层岩性分别以含角砾熔结凝灰岩和含角砾晶屑凝灰岩为主,断裂发育,是2个优质储层发育区。(2)研究区凝灰岩的测井和地震相特征相匹配形成的岩性-岩相模板可有效指导凝灰岩的地震相识别,振幅属性刻画出的火山口相、近火山岩相为有利岩性分布区。(3)研究区发育火石岭组、沙河子组、营城组3套优质烃源岩厚度均超过300 m,TOC值分别为0.26%~5.08%,0.10%~5.55%,0.10%~9.74%,S1+S2分别为0.24~8.23 mg/g,0.12~18.15 mg/g,0.25~2.86 mg/g,Ro分别为0.6%~1.3%,1.1%~1.6%,1.0%~2.2%,具有丰度高,成熟度中等的特征,为大规模成藏奠定了良好的物质基础。(4)研究区凝灰岩气藏是一套源储侧向对接、高位富集的致密气藏,成藏主要受构造样式、断裂发育程度和供烃窗口控制,其中拉张和伸展作用形成的叠瓦状断弯褶皱控制了油气富集程度,断裂发育程度及供烃窗口的大小决定了气藏规模。

Based on the core analysis,data of well logs and seismic,the distribution characteristics and oil-gas enrichment conditions of tuff reservoirs of Cretaceous Huoshiling Formation in Dehui fault depression of Songliao Basin were analyzed by using forward modelling and multi-parameter inversion body fusion technology,and the distribution of high-quality reservoirs was predicted.The results show that:(1)The tuff of Cretaceous Huoshiling Formation in Dehui fault depression,Songliao Basin,is a pyroclastic rock formed by fissure eruption,which mainly consists of breccia-bearing welded tuff,breccia-bearing crystal tuff and sedimentary tuff.The seismic reflection shows low frequency,poor continuity,medium strong amplitude or weak amplitude.The sweet spot distribution of tuff reservoirs predicted by multi-parameter inversion body fusion technology has a high coincidence rate with drilling data.The average value of tuff reservoir drilling catching rate is 92.8%,and the average gas reservoir drilling catching rate is 81.0%,among which 12 wells has obtained industrial gasflow.The reservoirs of Huajia structural belt and Guojia fault step belt are mainly composed of breccie-bearing welded tuff and breccie-bearing crystal tuff,with developed faults,making these two areas as the high-quality reservoir zones.(2)The lithology and lithofacies template formed by matching the well log and seismic facies characteristics of the tuff in the study area were useful to identify seismic facie of the tuff.It was confirmed that the crater and proximal crater facie characterized by amplitude attributes are favorable lithology distribution areas.(3)High-quality source rocks developed in Huoshiling Formation,Shahezi Formation and Yingcheng Formation have a thickness of more than 300 meters,with TOC of 0.26%-5.08%,0.10%-5.55%,0.10%-9.74%,S1+S2 of 0.24-8.23 mg/g,0.12-18.15 mg/g,0.25-2.86 mg/g,and Ro of 0.6%-1.3%,1.1%-1.6%,1.0%-2.2%,respectively.With the characteristic of high abundance and moderate maturity,they lay a good material foundation for a large-scale reservoir formation.(4)The tuff gas reservoir in the study area is a set of tight gas reservoirs with source and reservoir lateral connection and high enrichment.The accumulation is mainly controlled by structural styles,faults development and hydrocarbon supply windows.The imbricated fault-bending folds formed by tension and extension,is the major factor to control the degree of hydrocarbon enrichment,and the size of faults and hydrocarbon supply windows determine the gas reservoir scale.