Pressure buildup test technology for the vertical section of horizontal well

Conventional horizontal well test technologies cannot be used to test the pressure buildup curve in the conditions of normal production. To solve this problem, it is attempted to carry out pressure buildup test in the vertical section of horizontal well without pulling the string out of the hole. The effects on the pressure buildup test of horizontal well from the phase change of oil and gas and the movement of gas-liquid contact in the vertical wellbore were discussed. Then, a method was proposed to test the pressure in the middle of the oil layer in the horizontal well by applying the secondary construction method in the vertical section. In this method, the setting depth of the instruments in the vertical section shall be determined successively and the liquid column pressure at the setting point shall be kept higher than the bubble point pressure of crude oil at this point before the pressure buildup test is carried out in the vertical section of horizontal well. Finally, pressure buildup test was carried out in the horizontal section and vertical section of one certain horizontal well in Daqing Oilfield, and the characteristics of its pressure buildup curves in both tests were analyzed. It is indicated that by virtue of the secondary construction method based well test technology for vertical section of horizontal well, the effects of phase separation and gas-liquid contact movement on the form of pressure buildup curve are eliminated, the pressure in the vertical section can synchronously reflect the seepage information of the oil layer in the horizontal section, and its test interpretation result is better accordant with that of horizontal section.