| Du 84 block of liaohe oilfield ultra heavy oil reservoir petroleum oil bearing area of 6.2 km2,reservoir buried depth of 550 ~ 890 m,is suitable for the horizon of SAGD mining are: xing ? group,the xing ? group and guantao formation served reservoir.So far,the water content of the 48 Wells in the first stage of SAGD of du 84 block is 82.4%,the instantaneous oil vapor ratio is 0.18,the instantaneous injection ratio is 1.03,the cumulative oil vapor ratio is 0.31,and the recovery degree is 39.75%.From the perspective of geological characteristics,some problems need to be solved in development.Du 84 block of ultra heavy oil reservoir,xing ? group internal distribution of the unstable,uneven thickness of interlayer,lithology with mudstone,argillaceous siltstone and silty mudstone.The thickness and extension length of the septum are different,which affects the application effect of SAGD development method.Xing ? 40 m group reservoir thickness,xing ? 10 ~ 15 m reservoir thickness,reservoir thickness of SAGD development effect,the influence of thin layer dual horizontal well SAGD can improve the thin layer of ultra heavy oil reservoir recovery efficiency.Du 84 block of guantao reservoir is facing water drainage problem,SAGD drilling process,under the condition of steam injection,reservoir bitumen shell is closed,can block the top water drainage.Du 84 block of xing ? ? group and guantao group,xing have a certain degree of dip.These geological factors influence the development of SAGD.In order to further improve the mining effect of SAGD,it is necessary to carry out in-depth discussion on the above influential geological factors: isolation layer,thickness of oil layer,dip Angle of stratum and top water.This article through to du 84 block of guantao and xing VI group I,xing group of stratigraphic sequence and layer division,structure characteristics,sedimentary characteristics,reservoir characteristics,interlayer characteristics,reservoir characteristics,fluid properties,formation pressure and temperature further fine descriptions of geologic conditions and sorting,combing the main geological factors affecting SAGD development effect.And according to the above geological problem,set up the proportion of multiple sets of one-dimensional and two-dimensional physical model,and by means of this test and the physical simulation experiment to obtain data,image and detailed analysis of du 84 block,and the effects of ultra heavy oil reservoir geological characteristics of SAGD development,from the Angle of quantity,analyzes several factors influencing the effects and differences.Draws the following conclusions: the isolation layer of SAGD development had a greater influence on the ultimate recovery,the longer the interlayer of SAGD stage mining effect,the greater the recovery degree have obvious difference,length less than one-third less affected.The reservoir thickness has great influence on the development effect of SAGD.The development characteristics of SAGD steam cavity in two-and thick-bedded reservoirs are obviously different.SAGD in thin layer and double horizontal Wells has no economic benefit.Under the corresponding prototype conditions,the larger formation dip Angle is favorable to gravity oil discharge.Temperature is the top can water drainage of main control factors,the temperature below 160 ?,the high resistance layer linear seepage pressure difference is less than 12 MPa won't produce.Under the condition of 180 ?,differential pressure of 5 MPa produce linear seepage,does not have the packer ability at this time.Asphalt shell core displacement temperature greater than 180 ?,pressure difference is not more than 10 MPa,did not produce linear seepage.The viscosity of asphalt shell is much higher than that of high resistance layer,and the condition of water passing through asphalt shell is higher.In order to ensure that the top water does not flow down,the height of the steam cavity must not exceed a certain limit. |
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