肯基亚克盐上油田白垩系曲流河三角洲存在的证据与沉积特征

Evidences and Sedimentary Characteristics of Cretaceous Meandering River Delta in Up-salt Kenjiyake Oilfield

为理清哈萨克斯坦肯基亚克盐上油田白垩系砂体成因特征,指导油气田开发。在高密度井网条件下,利用岩心、岩石薄片、分析化验、古生物、测井等综合资料,研究储层砂体的粒度、结构、成分及砂体平面展布规律。结果表明:白垩系下统巴列姆组储层主要是细砂岩及粉-细砂岩;具有小型交错层理和水平层理,砂岩成分成熟度中等、结构成熟度较高。西北部三角洲平原有明显的二元结构及向上变细的正韵律,砂体整体呈朵状展布,具有典型的曲流河三角洲沉积特征;可识别出三角洲平原、三角洲前缘、前三角洲、浅湖4种亚相以及水上分支河道、水下分支河道、浅湖砂坝等10个微相,并分析了各微相的沉积特征及砂体展布形态;其中巴列姆二段时期三角洲前缘亚相主要分布在工区中西部,巴列姆一段时期工区整体演变为前三角洲——浅湖亚相,为一典型的退积式三角洲;该研究结果为肯基亚克油气田的开发提供了重要的地质依据。

In order to clear the cause of sand body of the lower Cretaceous in up-salt Kenjiyake oilfield,the oil and gas fields＇ development were guided. Therefore,under the condition of dense well pattern,the comprehensive data of core,rock slices,analysis and laboratory,ancient biology,well logging and so on to study the granularity,structure,composition of the sand body＇s reservoir and the distribution law of sand body was used. Then the results show that： the reservoirs in Baliemu formation of the middle Cretaceous are mainly fine sandstone and siltstone;Sandstone has some small cross bedding and horizontal bedding; the compositional maturity of sandstone is medium while the texture maturity of sandstone is high. Delta plain that is in the northwest has the Dual Structure. Vertically,the upper the sequence,the finer the grain size; The sand body in the study area is distributed in a single shape,this form has the typical sedimentary characteristics of the meandering river delta; In this areas have been identified delta front,delta plain,frontal delta,shallow lake,including 10 kinds of microfacies： distributary channel,subaqueous distributary channel,shallow lake sand bars,ect. At the same time the distribution patterns of sand bodies and the sedimentary characteristics have been analyzed; During the second member of Baliemu formation period delta front subfacies main distribute in the west of the study area,while in the first member of Baliemu formation period the whole area evolves the former delta-shallow lake subfacies which is the typical retrogradational delta; This study provides important geological basis for the development of Kenjiyake oilfield.