利用单渗砂层优势微相带概念精细评价有利沉积微相及其剩余油分布——以温西三块储层、水淹层评价为例

Using the concept of single permeability sand layer favorable microfacies belt to refinedly evaluate favorable sedimetary microfacies and remaining oil distribution:Taking the evaluation of Wenxisan block reservoir and water flooded layer as example

针对温西三块三间房组辫状河三角洲前缘储集砂体受河道水流和湖浪双重作用,在注水开发中砂体结构、赋存状态及剩余油分布复杂的特点,提出利用单渗砂层优势微相带概念精细评价有利沉积微相及其剩余油分布的方法。该研究利用在砂层沉积时间跨度内,垂向叠置演化的各单渗砂层的能量厚度,确认出辫状河三角洲前缘各种不同类型主体和非主体储集砂体微相带的发育及演化特征,不但克服了薄差砂层叠加厚度识别主体储集砂体河道、河口坝微相带的失误,而且在垂向上有效地评价出了与主体微相叠置演化的河道边远梢席状砂、远砂微相砂体。该文利用单渗砂层优势微相带概念,通过目的层段单渗砂层能量厚度及其岩性、物性和自然电位减小系数、自然伽马减小系数、声波时差、密度、中子孔隙度、深侧向、深感应电阻率建立精细评价有利沉积微相的单渗砂层能量厚度标准,准确提取单渗砂层优势微相带的沉积能量及其测井参数信息,有效地展示出目的层段单渗砂层能量厚度垂向演化的水下分流河道、河口坝、席状砂、远砂微相平面展布规模和范围,并列举出注水开发中主体微相河道正向叠置韵律层中的层间差异层和非主体微相席状砂层受河道高渗层间干扰造成的剩余油分布层段,为准确预测和筛选不同类型已动用油层及未动用(或基本未动用)油层剩余油分布提供了可靠的地质依据。

In view of the dual function of river water and lake wave at Wen Xisan Block, San Fangjian forma- tion braided river delta front reservoir sand, and the characteristics of sand structure, occurrence condition and complex remaining oil distribution in the waterflood development, the paper puts forward using the concept of single permeability sand layer favorable microfacies belt to refinedly evaluate favorable sedimentary microfacies and remaining oil distribution. The single permeability sand layer energy thickness is used, which vertical su- perimposed evolution in the sedimentary period of sand layer, to confirm favorable microfacies belt develop- ment, scale and distribution range of braided river delta front underwater distributary channel, mouth bar, sheet sands, and far sand. This not only effectively overcomes the mistakes made in similar causes poor thin sand layer or sand mud interbed sand layer accumulative thickness identification and body skeleton channel sand body, river mouth bar microfacies belt partition, but also avoids losing remote sheet sand, distal sand mi- crofacies sandbodies which vertical superimposed evolution with the main microfacies. Thus, in this paper, fa- vorable single permeability sand microfaeies belt concept is taken, through the single permeability sand layer thickness, self-potential decrease coefficient, natural gamma ray decrease coefficient, acoustic interval, densi- ty, neutron porosity, deep lateral, deep induction resistivity and lithology, porosity, permeability of objective strata, to set single permeability sand layer energy thickness refined evaluation standard of favorable sedimen- tary mierofacies, accurately extracting single permeability sand favorable sedimentary microfacies belt sedimen- tary energy and logging parameter information, effectively showing the plane distribution scale and scope of single permeability sand layer energy thickness vertical evolution underwater distributary channel, mouth bar, sheet sand, distal sand microfacies at the objective strata, and citing that in the waterflood development the strata remaining oil distributed is caused by differential layers in main microfacies river channel positive super- imposed rhythmite and non-subject microfacies sheet sand layer disturbed by river channel high permeability layer. Those made a reliable geological basis to accurately predict and filtrate remaining oil distribution in dif- ferent types of used and unused （or basically unused） reservoirs.