Dynamic Analysis Of Horizontal Well Development And Rational Development Strategies In Mahu Tight Conglomerate Reservoi

Mahu tight conglomerate reservoir is rich in oil and gas resources and has great development potential.However,in the process of exploration and development,it is found that the initial oil production and pressure decrease rapidly and greatly.And the difference between different layers is large,with strong heterogeneity,strong stress sensitivity,strong water sensitivity characteristics.The production dynamic characteristics of fractured horizontal wells are complex,the analysis of productivity controlling factors is not clear,and there is a lack of reasonable prediction methods and processes of EUR.Meanwhile,unreasonable development strategies affect fracturing and post-fracturing productivity.In this paper,the fracturing horizontal well of Upper Wuerhe formation in Mahu sag is taken as the research object,the production dynamic characteristics and influencing factors of horizontal well productivity are studied,the reasonable prediction method of EUR is explored and the reasonable development countermeasures are proposed.The main achievements are as follows:(1)By analyzing the cumulative oil production of the three layers in the block and combining with the flow material balance method,it is concluded that the oil production capacity and single well controlled reserves of the P3w1~1 and P3w2~2 reservoirs are relatively high and have the most potential for reconstruction.(2)Ten productivity prediction methods(Arps,Duong,SEPD,YM-SEPD,short history prediction,Fetkovich,Blasingame,regression-hyperbolic,Duong-hyperbolic,analytical model)and their application scope are systematically analyzed,and EUR prediction is made for horizontal wells in the study area block.It is obtained that the regression-hyperbolic method and Duong-hyperbolic method are used to predict,and the analytical model is used to verify the results.The analytical model can be used to predict the well with short production history of one year or so.(3)The relationship between the influencing factors and the cumulative production in the first year is analyzed from the three perspectives of geological parameters,engineering parameters and production system.First,the comprehensive weight is calculated by the analytic hierarchy process and the entropy method.Finally,the weighted grey correlation method is used to analyze the main controlling factors.The method of equal rights is more in line with the complexity and imbalance of the factors affecting the production capacity in the actual situation.In terms of geological parameters,the main influencing factors are clay mineral content;in terms of engineering parameters,the main influencing factors are sanding intensity and liquid intensity;in terms of production system,the influencing factors are nozzle system and boring time.(4)Based on production dynamic analysis and reservoir characteristics,It is suggested that the P3w1~1 horizon should be the first choice for transformation,then the P3w2~2 horizon should be transformed,and finally the P3w2~1 horizon should be selectively developed.Due to low clay mineral content and weak water sensitivity,the P3w1~1formation can be fractured on a large scale,which is not suitable for post-fracturing shut-in to improve long-term productivity.Due to the high content of clay minerals and strong water sensitivity,P3w2~2 formation is prone to unstable phenomena such as expansion,dispersion or flocculation,which is prone to fracture narrowing and affect productivity.Therefore,it is not suitable for large-scale fracturing and post-fracturing shut-in.(5)The fracture volume loss rate of 180 days after production was analyzed.Because the Mahu conglomerate reservoir has strong stress sensitivity,the fracture volume loss rate is generally large.The fracture volume loss rate in P3w1~1 formation is the smallest,and that in P3w2~1 formation is the largest.In order to avoid the increase of fracture volume loss rate,small nozzles of 1.5mm～3mm should be used at the initial stage of drainage and production,which should last for half a year or more.After that,large nozzles of 3.5mm and above should be used to increase production pressure difference and improve productivity.