Research On High Temperature Profile Control Ball And Selective Hole Sealing Technology For Heavy Oil Thermal Production

With the development of steam flooding heavy oil thermal recovery technology,the longitudinal contradiction becomes more and more prominent.The current conventional method is to adjust the longitudinal steam absorption profile by stratified steam injection process.The stratified steam injection process uses packer to seal oil layer.With casing damage and deformation,the technology cannot be realized due to the limitation of wellbore integrity.In order to solve this problem,selective hole sealing technology is usually used to solve the problem.At present,the life of profile control ball used in selective hole sealing technology in China is generally very short,and fracturing and opening are often occurred.At the same time,the process of selective hole sealing is complicated and changeable,which is difficult to control,and the success rate of ball throwing often fails to meet the requirements,and the steam utilization rate is low,leading to excessive waste.In this paper,a long-acting profile control ball with promising application is designed.The structure of the profile control ball is selected as a hollow ball of titanium alloy,with an overall density of 0.6g/cm3.The manufacturing of profile control ball adopts the method of pressing the hollow hemisphere of titanium alloy,and the two hemispheres are welded together by cold welding.Finally,the compressive strength of the profile control ball is tested.In order to solve the problem of the success rate of the ball sealing hole,so as to improve the steam longitudinal utilization effect.In this paper,hydrodynamic analysis is adopted to establish the motion and dynamic mathematical model of profile control ball,and methods of laboratory test and Fluent fluid simulation test are carried out.An indoor simulation device for selective sealing hole was built to simulate the osmotic pressure of each underground oil layer by controlling the flow rate,and to investigate the condition of profile control ball and ball under the conditions of different number of perforation layers and different flow rates.The fluid simulation experiment was designed by comparing with the laboratory test.The experiment was carried out by setting different boundary outlets and different proportional pressure values.According to the simulation results,the motion trajectory of the profile control ball was analyzed to verify the reasonableness and validity of the laboratory test.The results show that the success rate of pitching can be improved by improving the air tightness of the equipment,improving the air injection volume,and moderately changing the fluid density,small ball radius,mass and other factors according to the kinematic mathematical model of profile control ball.Thus,it can provide guidance for field oilfield exploitation and improve steam flooding heavy oil thermal recovery efficiency.