Quantitative Characterization Of Interlayer In Donghe Sandstone Reservoir Of Hudson Oilfield

Hudson oilfield in Tarim Basin is the first large marine sandstone integrated oilfield with proved reserves of more than 100 million tons in China.It has entered the stage of high water cut,and the distribution of remaining oil is complex.Interlayer is an important reason for the complex distribution of remaining oil.In the past,the research on the interlayer in this study area is mostly qualitative,but the quantitative characterization is relatively weak,which makes it more difficult to accurately predict the distribution of remaining oil.In view of the above problems,this paper integrating core,logging,production and analysis of laboratory data,based on the genesis research of interlayer,carried out quantitative fine characterization of interlayer through interdisciplinary integration,and finally established the remaining oil distribution mode controlled by interlayer.The research results and understandings are as follows:Fine characterization of sedimentary microfacies controlled by isochronal stratigraphic framework is carried out.According to the principle of sequence stratigraphy,four kinds of sequence interface in the study area were identified,including sequence interface,parasequence set interface,parasequence interface and strata group interface,and the sequence stratigraphic framework of the study area was established.According to the core and logging data,the sedimentary subfacies in the study area are divided into nearshore,foreshore and backshore subfacies,which are subdivided into bar micro-facies,beach micro-facies and groove microfacies.Based on the data of core,logging,analysis and production performance,the genesis and quantitative characterization of interlayer are studied,and the main work and achievements are as follows:(1)There are three types of interlayer in the study area,which are argillaceous,calcareous and calcareous-argillaceous interlayer.The basic characteristics and the logging response characteristics are defined,and the logging identification standard is established;(2)The argillaceous interlayer can be divided into five genetic types,and the calcareous interlayer can be divided into three genetic types;(3)According to the sequence stratigraphy and configuration theory,the classification of interlayer grades is divided into four grades.The vertical development characteristics of different grades of interlayer are characterized by the average thickness and average drilling rate of the interlayer.It shows that the vertical development of interlayer is controlled by the relative change of sea level;(4)The dip angle and dip tendency of interlayer are quantitatively characterized by dip log data.The results show that the dip angle of interlayer is 0～5°,and its dip direction is perpendicular to the paleoshoreline;(5)Based on the genetic model of interlayers,the quantitative characterization of interlayers is carried out by using the method of combining vertical wells with horizontal wells,and the quantitative relationship between the maximum thickness and the maximum extension length of interlayers parallel to and perpendicular to the paleoshoreline is clarified.Parallel to the paleoshoreline,the extension range of interlayer and interbed is 516～4560m and344～1509m respectively;Perpendicular to the paleoshoreline,the extension range of interlayer and interbed is 439～2549m and 265～974m respectively;(6)According to the results of quantitative characterization between wells,the distribution characteristics of interlayers between wells are analyzed,and the plane distribution characteristics of interlayers are characterized by thickness and frequency parameters,and the interlayer model of the study area is established.Combined with production data and dynamic monitoring data,the influence of interlayer on remaining oil distribution is analyzed and the remaining oil distribution model under the control of interlayer is established.The above research provides a scientific basis for the further development and EOR of Hudson oilfield,and also provides ideas for the study of interlayer and remaining oil distribution in other similar littoral facies reservoirs.