Study On The Oil-water Two-phase Water-Cut Electrical Measurement Method In Horizontal Well

At present,CNPC has nearly 7,000 horizontal Wells,The scale of horizontal well will be expanding with the improvement of horizontal drilling and large-scale fracturing technology.Water flooding is an important factor affecting the development of horizontal wells.After water flooding,water cut of horizontal wells rises sharply.Perfect production testing technology of horizontal wells can provide technical support for water shutoff or fracturing plans.Influenced by the flow pattern of horizontal wells,the current water cut testing technology is still imperfect and can not meet the needs of production testing of horizontal wells.Based on the actual development and testing requirements of horizontal wells in domestic oilfields,this paper applies advanced computer finite element electric field and hydrodynamics simulation technology,and combines dynamic simulation experiments to carry out the research on water cut measurement method of horizontal wells by electrical method.Firstly,in order to solve the problem that the complex flow of oil-water two-phase flow affects the accuracy of water-cut measurement sensor under horizontal conditions,the flow pattern and distribution characteristics of oil-water two-phase flow in horizontal pipeline are studied by combining FLUENT simulation and dynamic experiment.The simulation models of three kinds of horizontal pipelines were established to study the flow state of oil-water two-phase flow in horizontal pipelines at different inclination,flow rate and water content,and the influence of flow state on sensor measurement.By building simulation experiment platform and carrying out dynamic research,we got flow pattern distribution map and verified the validity of simulation.Secondly,a new method of measuring water conductivity using circumferential conductivity probe array under horizontal conditions is studied to solve the problem that water phase conductivity can not be obtained by existing conductivity water-cut meter under horizontal oil-water two-phase laminar flow conditions.According to the oil-water distribution characteristics of horizontal oil-water layered flow,the structure model of the water conductivity measurement method with circumferential conductivity probe array is designed.The electric field distribution and response law of the model under different electrode structure and horizontal angle are studied by ANSYS software,and the corresponding response relationship between the model and the conductivity water-cut meter under different salinity is also studied.The prototype of the model was designed and static experiments were carried out at different horizontal angles,temperatures and salinities to verify the feasibility of the model for measuring water-cut.Thirdly,a new type of capacitance water-cut measurement method for horizontal wells is studied to solve the problem of low resolution of traditional coaxial capacitance water-cut meter in water cut measurement of horizontal wells with low fluid production.The principle analysis of coaxial,cylindrical and new structure capacitance water cut measurement method is carried out,and the structure model of new capacitive water-cut measurement method is constructed by COMSOL software.The sensitivity distribution of the model under different electrode length,channel radius and insulation thickness is analyzed,and the optimum model structure design scheme is obtained.The model is analyzed in different flow patterns and different bubble contacts of horizontal wells.The flow regime range of the model in horizontal wells is obtained,which lays a foundation for the development of a new type of capacitive water cut meter.Finally,a new prototype of conductivity and capacitance water cut measurement method is designed and developed.The dynamic experiment of oil-water two-phase flow is carried out in horizontal simulation wellbore,and the response law and measurement accuracy of the two water cut measurement methods under different flow and water cut conditions are analyzed.Field tests of horizontal wells are carried out to analyze the field test results of the new electric water cut measurement method,and the practicability of the new structure electric water cut measurement method is verified by field tests.