Delta Front Architecture Characterization Of Braided River Based On Combination Of Well And Seismic And Its Controlling Factors

The Triassic TⅠand TⅡoil groups in Lunnan Oilfield are the main production layers of Lunnan Oilfield.As the reservoir water flooding development keep deepening,the internal structure of reservoir sandstone body must be studied deeply.In this paper,based on the predecessors’ studies,the development of a set of sparse well area of the combination of well modeling method,the control factors and the remaining oil distribution will be studied.Using the core,logging and seismic data together to establish a fine isochronous stratigraphic framework in the study area.Taking the outcrop of Huangshanjie Formation in Kuqa County of Tarim Basin as the research object,fine anatomy braided river delta tectonic unit,and clear the qualitative overlapping pattern and quantitative distribution pattern between different configurations.Using the analytic hierarchy process and classifying the anatomical braided river delta front configuration.In the wellbore area,use the guidance of outcrop model to anatomy underground well area,and establish a single underwater diversion channel identification mark.In the sparse wells area,use positive and negative combination of seismic analysis method to study.First of all,use the quasi-acoustic seismic inversion method to predict the plane distribution of sand bodies in different target layers.Then based on the prediction,the five-level configuration of the target layer is studied using the method of single-well microfacies-sedimentary microfacies plane combination bounded by the result of seismic data inversion.On the basis of the five-level configuration anatomy,by the simulation of seismic forward data,the seismic data single underwater diversion channel boundary identification is carried out,the conceptual model of underwater distributary channel,diversion bay and sand bar under different superposition relation is established,and compared with the actual seismic profile,the underwater distributary channel boundary with different characteristics is identified according to the characteristics of peak size,misalignment,thickening and offset.Based on the identification of single underwater distributary channel,identify the interlayer of underwater distributary channel.The interlayer is divided into three types,including mud interlayer,calcite interlayer and physical interlayers,of which the muddy interlayer formation model is divided into the preservation of complete and incomplete preservation;calcium calcite is mainly due to the mechanism of inorganicgenesis,generally developed in the bottom of the underwater distributary channel sand or the top;physical interlayers distributes in the underwater diversion channel flank with relatively poor physical properties.And analyze the spatial distribution characteristics of the interlayer.The mechanism of the control of the reservoir structure is studied and the ultrashort term base cycle has a controlling effect to the distribution of the interlayer in the four-stage reservoir configuration unit.In the upward shoaling short-term cycles,there are relatively more interlayers and the lateral continuity is more stable;while in the upward deepening ultrashort term cycles,the number of interlayers is small and the interlayer is unstable.The short term base cycle has a controlling effect to the distribution mode of the four-stage reservoir configuration unit.In upward shoaling short-term cycles,the number of single underwater distribution is small,with a small size and isolated distribution;while in upward deepening short-term cycles,the number of underwater diversion of river development is big,with large scale and overlapping features.The mid-range base cycle has a controlling effect to the distribution mode of the five-stage reservoir configuration unit.In upward shoaling mid-range cycles,the number of configuration units is small and the units are small in size;while in upward deepening mid-range cycles,there are more configuration units with bigger size.The remaining oil distribution characteristics of reservoir configuration control are analyzed,and the connectivity of the configuration unit is divided into three types:the interconnected type,the weakly connected type and the connected type based on different configuration unit superposition relationship,so causing the distribution of remaining oil appears strong washing,washing and weak water washing separately in vertical.The interlayer development plays a double control effect on the remaining oil distribution,when the interlayer development has a high density,it plays a positive role in the development of oil recovery wells;when the interlayer development has a low density,remaining oil is formed in a hydrodynamic retention zone formed in the upper or lower part of the interlayer.