Study On Prediction Model Of Horizontal Well Temperature Profile

As the fracturing technology is widely used in the development of low-permeability sandstone reservoir, it is of great significance to obtain the horizontal well inflow profiles and performance. The conventional horizontal well test has problems in terms of difficulty, accuracy and cost, while the accurate and real-time temperature and pressure data in wells could be observed by the Distributed Temperature System (DTS) which emerged recently. The interpretation of these data could be used to obtain the well inflows, but it needs the establishment the temperature prediction model.In this paper, based on a large number of domestic and foreign literature review and the mechanism of reservoir seepage and wellbore flow, the temperature prediction mechanic model of fractured horizontal wells was established, which took into account the micro-scale heat effect and the reservoir-horizontal wellbore coupled model. Then the main influencing factors of horizontal wellbore temperature profile were analyzed.The main work and conclusions in this paper are as follows:1) Theoretical derivation of the temperature prediction model, which considers the viscous dissipation, thermal expansion, including the reservoir model, the wellbore model and the coupled model established by analytical method.2) The temperature prediction mechanic model was established by using numerical simulation software and Matlab programming to calculate fluid coefficients, wellbore pressure profiles, arriving temperature profiles and wellbore temperature profiles.3)The temperature different between wellbore and reservoir inflow plays a dominate role in the wellbore temperature behavior:①Due to the viscous dissipation heating and the thermal expansion, the arriving temperature shows clear temperature decrease at the fracture location, which causes the wellbore temperature decrease at the same place. On the other hand, because of no reservoir inflow, the wellbore fluid is heated up by the higher temperature formation at the non-perforated location. And the process is repeated from the first fracture to the last one.②Wellbore temperature is affected by the fluid mixing effect too:as the flowing fluid increase in the wellbore, the temperature change is getting smaller from the "toe" to the "heel"4) In the situation of a constant rate, the main influencing factors of horizontal wellbore temperature profile were analyzed. The conclusion is that:①The temperature drop will decrease when the fracture network is considered.②The temperature drop augments with the increase of fracture half-length.③The temperature drop decreases with the increase of fracture conductivity and fracture number.