喇嘛甸油田一类油层微观剩余油分布规律及其成因分析

Distribution Law and Genesis Analysis of Micro-Residual Oil in the Class I Reservoir in Lamadian Oilfield

大庆喇嘛甸油田一类油层已进入两驱并存的高含水阶段,由于剩余油分布极为复杂,无效驱替增加,剩余油挖潜难度日益加大。针对以上问题,通过铸体薄片鉴定、扫描电镜及荧光薄片分析等实验分析方法,在明确了储层物性、微观孔隙结构的前提下,重点研究了该油层的微观剩余油类型、赋存状态、分布规律及其成因机理。结果表明:储集空间类型包括原生孔隙和次生孔隙两大类,并以次生溶蚀孔隙为主,微观孔隙结构以发育大孔喉半径为特征,并具有良好的分选性和连通性;一类油层微观剩余油呈现束缚态、半束缚态、自由态等3种赋存状态,进一步可划分为膜状、簇状、网络状(连片状)、粒间吸附状、喉道状、角隅状等6种类型,且以前3类微观剩余油为主;微观剩余油成因机理复杂,主要受到储层物性、微观孔隙结构以及驱替方案的影响与控制。

Class I oil layer of Lamadian Oilfield in Daqing has entered into the high water-cut stage of the coexistence of water and polymer flooding.Due to the extremely complex distribution of remaining oil and the increase of ineffective displacement,it is increasingly difficult to tap the potential of remaining oil.Aiming at the above problems,through experimental analysis methods such as casting thin section identification,scanning electron microscope and fluorescent thin section analysis,on the premise of clarifying the reservoir physical properties and micro-pore structure,the types,occurrence states,distribution law and genetic mechanism of the micro-residual oil in the reservoir were analyzed.The results show that:reservoir space types include primary pores and secondary pores,mainly secondary dissolution pores;The micro pore structure is characterized by the development of large pore throat radius with good sorting and connectivity.The microscopic remaining oil of class I oil reservoir presents three occurrence states,including bound state,semi-bound state and free state,which can be further divided into six types,including membrane,cluster,network(continuous),intergranular adsorption,throat and corner,and the former three types of micro-residual oil are dominant.The genetic mechanism of micro residual oil is relatively complex,which is mainly affected and controlled by reservoir property,micro-pore structure and displacement scheme.