Research On Parameter Optimum Selection And Adjustment Strategy Of SAGD In Zhong 1 Block Of Fengcheng Oilfield

Steam-assisted gravity drainage(SAGD)technology is a heavy oil thermal recovery technology with good economic benefits for mining ultra-heavy oil reservoirs in recent years.Compared with the heavy oil thermal recovery method of steam stimulation and steam flooding,SAGD technology can not only improve the development speed of super heavy oil reservoirs,but also effectively improve the ultimate recovery rate.Thus,it can reach economic benefits that other thermal recovery methods cannot achieve.Therefore,the research of SAGD technology is of great significance for the development of such heavy oil reservoirs.The ultra-heavy oil reservoir of Xinjiang Fengcheng Oilfield has the characteristics of high viscosity and shallow burial,which is a typical super-heavy oil reservoir.The SAGD method has been well used and developed in its development process,providing a reliable basis for further exploration of SAGD technology in China.However,in the development process,due to factors like reservoir heterogeneity,the current mining can not fully achieve the expected results,and further analysis of the application should be combined with examples to improve the application.In this paper,the numerical simulation method is taken as the main method.For the problems in the SAGD process,such as the inconsistency of the horizontal well section and the obstruction of the steam chamber expansion,the parameters optimization and adjustment countermeasures are studied.(1)Re-recognize geological features and development characteristics through research literature and materials;(2)Analyze the changes in production characteristics and thermal connectivity of the SAGD well group during the cycle preheating stage and production stage.Through the method of numerical simulation,the mechanism model was established and used to analyze the factors affecting the permeability,oil layer thickness,different types of interlayer and steam injection pressure,horizontal section driving length,production ratio,steam dryness and sub-cool.analysis;(3)By means of orthogonal experiment and numerical simulation,it is concluded that the main controlling factors of reservoir thickness,permeability,interlayer closure,horizontal section utilization degree and steam injection pressure on cumulative oil production and daily oil production are reservoir thickness and interlayer closure respectively.Taking 42 pairs of well groups as samples,the well components in the block are classified into three categories according to porosity,permeability,oil saturation,reservoir thickness,horizontal section length,reserves abundance,daily steam injection,daily liquid production,daily oil production,water cut,production-injection ratio,oil-gas ratio,produced reserves and cumulative oil production.;(4)Taking G03 well group,G15 well group and G3U well group as typical well groups,the history fitting and production performance prediction are carried out by numerical simulation method,and the remaining oil distribution characteristics of typical well groups are analyzed;(5)By means of numerical simulation,the parameters of steam injection speed,production-injection ratio,steam injection pressure,dryness and sub-cool are optimized for the first group of wells.For the second type of well group,the measures of SAGD assisted by vertical wells are adopted,and the assistant measures are divided into two stages,i.e.steam huff and puff of vertical wells and continuous steam flooding of vertical wells.The steam huff and puff pressure,steam injection rate,soaking time,rotation and injection-production index of vertical wells in thermal connectivity stage are optimized.The parameters of steam injection speed and production-injection ratio in auxiliary stage of steam flooding are optimized.Horizontal well assisted SAGD measures are adopted for three types of well groups.The assistant process is divided into two stages of assisted horizontal well steam stimulation and production,and the injection and production parameters of two stages are optimized.The purpose of improving the sweep range of steam chamber and the utilization degree of horizontal section is achieved,and the efficient development of oilfield is realized.This study has important significance for further efficient development and adjustment of Zhongl oilfield,and has certain reference value for the same type of block adjustment or improvement of SAGD development effect.