MODEL TEST ON SEEPAGE REGULAR PATTERN OF HORIZONTAL WELL IN LOW PERMEABILITY FORMATION

In order to study the seepage characteristics of horizontal well in low permeability formation,a self-designed model test device is used to monitor the seepage regular pattern of different aquifer thicknesses and different pump positions by embedding micro pore pressure sensor. The thickness of different aquifers was 60,79,94,113,and 123cm,respectively. The locations of the pump are at the ramp section,the entrance of the horizontal section,and the horizontal section. The test results show that the seepage regular pattern of different aquifer thicknesses is that with the increase of aquifer thickness,the pore water pressure and unit discharge increase,but there is a limit value. According to this experiment,it can be concluded that there are constraints among aquifer thickness,formation permeability and horizontal well completion structure. When the thickness of aquifer exceeds 207cm,under the same test conditions,the unit flow tends to be stable,indicating the advantages of horizontal well in low permeability and thin layer mining. When the pump is located at different positions in the horizontal well,the pore water pressure distribution in the aquifer is similar. The position of the pump mainly affects the radius of influence of the falling curve and the corresponding flow. According to the slope building section,the entrance of the horizontal section and the range of influence of precipitation in the horizontal section,the flow increases. Therefore,it is beneficial to increase production capacity to place pump in horizontal section in low permeability formation.