Study On Sedimentary System Of Permian Wutonggou Formation In Lukeqin Area

The Lukeqin area locates in the central part of Turpan depression,Wutonggou formation reservoirs is the main oil producing and the key exploration targets of this area at present.There are still some problems in the basic research of sedimentary: The main types of sedimentary facies are controversial;the spatial distribution of sedimentary facies is not clear,especially in the area without well.In view of these problems,the comprehensive utilization of geological,seismic,well-logging and analysis and laboratory tests is used to study the sedimentary system.The main research contents include the division and correlation of the oil layer and the small layer,the analysis of the sign of the rock facies,the analysis of the geochemical facies,the distribution of sedimentary facies,sedimentary evolution and sedimentary model analysis.The main results achieved are the following several aspects:(1)By re-determining the top and bottom boundaries of Wutonggou formation,the identified 3 reservoir groups has been further subdivided into 7 small layers: W1 oil group of 2 small layers,W2 oil group of 2 small layers,W3 oil group of 3 small layers.The overlap boundary and denudation boundary of three oil groups has been re-determined by using the way of well-seismic combination.(2)Wutonggou formation sedimentary deposited in faulted sag,controlling by synsedimentary faults.Luxi salient and Kumu salient provided sediment source respectively from the southwest and Southeast and controlled deposition.The rock facies marks reflects the change of water depth and the complex and changeable hydrodynamic.The well-logging facies marks and seismic facies marks reflect the typical characteristics of continental lacustrine fan deposits(3)There are 5 types of sedimentary facies in the study area: underwater alluvial fan,fan delta,alluvial fan,slump turbidity fan,shallow lake and semi deep lake.Underwater alluvial fan develops 3 subfacies: fan root,mid-fan and fan end,the braided channel microfacies of midfan subfacies is the main body.The fan delta consists of 3 subfacies: front verge subfacies,outer front verge subfacies and pro-fan delta,the development of front verge subfacies controlled of the flow channel is the most extensive.Alluvial fan develops 3 subfacies: fan root,mid-fan and fan end,mainly develops mid-fan,fan root was less developed.(4)The seismic facies analysis based on K-means clustering algorithm combine with percentage content of sand and gravel,can accurately divided subfacies,determine the facies boundary.The distribution characteristics of sedimentary facies of Wutonggou formation were carried out.Vertically,the fan facies presents many times of the stack overlap characteristics,channel and inter-channel present many times in small layers parts.On the plane,presents depositional characteristics of two main fan body propulsion,mid-fan subfacies are most widely distributed in each period.(5)Four sedimentary evolution stages of Wutonggou formation are expounded: the initial rift period;the extension of the transition period,the period of the dry deposition,and the stable sedimentary period.Established in line with the study area of each sedimentary evolution stage of the sedimentary facies model,namely the faulted basin at the end of the underwater alluvial fan deposition model,the uplift process of fan delta depositional model and alluvial fan depositional model and stable depression of fan delta sedimentary model.