Research On Micro-Structure And Its Effects On Remaining Oil Of The Middle Es₃ Member In Block Fan 29,Daluhu Oilfield

Block Fan 29 is a typical turbidite and low-permeability oil reservoir.With years of exploration and development,Block Fan 29 now has turn into stage of high water cut,and problems has occurred recently,like ambiguous understanding on remaining oil distribution Remaining oil distribution is not only dominated by sedimentary microfacies,reservoir anisotropy and dynamic exploitation factors,but also controlled by micro-structure,especially at the late stage of oilfield development or even during oil well's production phase Micro-structure research becomes important in geologic structure research,especially at the late stage of oilfield developmentDuring the research,firstly,targeted interval has been exquisite divided and compared by utilizing core and logging information.The Middle Es3 Member in Block Fan 29 is divided into 4 sand groups:42,43,44,45;And under each of the 4 sand groups,there are 4 set of single sand layers,which makes total 16 set of sand layers.Based on first step segmentation,the research among sedimentary microfacies has carried out.Targeted layers are lakebed turbidite fan deposition,which mainly developed middle fan and outer fan subfacies,while central fan subfacies is further segmented into microfacies like main water channel,inter channel,lobes and middle fan lateral margin.And sedimentary microfacies mode has been established at the same time,which fit sedimentary characteristics of research areaFinally,by compiling 16 set of top/bottom sand layers,micro-structure map has been established.There are 8 types of micro-structure distinguished during the research,including micro-anticline,micro-nose,micro-faulted nose,micro-syncline,micro-groove,micro-faulted groove,micro-slope,micro-terrace.Among all types of micro-structure,micro-slope and micro-nose has been extensively developed.And there are 6 types of micro-structure configuration mode,including top convex-bottom convex,top flat-bottom flat,top concave-bottom concave,top convex-bottom flat,top flat-bottom concave,top concave-bottom flat,while top convex-bottom convex mode is the most common mode Controlled by macroscopic terrain,micro-structure's concentrating distribution is around high spot in relative gently central part of research area.Micro-nose and micro-groove surrounded the high point to make it ringwise.And micro-structure developing has strong capacity of inheritance.Main cause of micro-structure in research area contains construction factor and non-construction factor,while the former is usually the main cause.Non-structural factor include sedimentary environment,differential compaction and ancient terrain.The inheritance of micro-structure developing is mainly controlled by the fluctuation of the ancient terrain and faulting.Production data shows that positive micro-structure most likely to be high-productivity well,while negative micro-structure turns to be low-productivity well.Top convex-bottom convex configuration mode has highest well productivity while top concave-bottom flat and top concave-bottom concave mode has lowest well productivity From superimposition of sedimentary microfacies map and micro-structure map,it shows that yield becomes highest when positive micro-structure coincides with main water channel.The yield between different adjacent wells on the same sedimentary microfacies area can be extremely different due to micro-structure discrepancy.