Numerical Simulation And Application Of Foam Fluid On Sand-flushing

Through laboratory experiment, several kinds of foaming agents which are often usedin oil field are researched. The abilities of foaming, salt resistance, oil resistance, andtemperature resistanceof the agents were extimated. The result shows that LJH-03 hasgood performance, and the best concertation of LJH-03 is 0.8%. The composition ofstabilizer system is (0.4-0.6)%CMC-HV+(0.3-0.5)%PAM. Rheology and static viscosityof foam fluid were gained.Sand-flushing of direct well, inclined well and horizontal well was resezrched.Discrete phase mode in FLUENT was used to simulate sand carrying capability of foamfluid, and relations of sand carrying rate and residence time in foam fluid to inclinationangle of annular pipe and fluid velocity were researched. The simulation results of foamfluid were compared with that of water on the same condition, and qualitative analyseswere provided. It can be seen that sanding carrying capability of foam fluid is muchbetter, and it is especially suitable for sand-flushing of horizontal well. Sand carrying rateis increased with the increase of foam fluid velocity, and it is decreased because of annular spaceeccentricity. The impact of annular space eccentricity on horizontal segment is fiercer than that onvertical segment of oil well.Based on mass and momentum conservation equations, mathematical model forsand-flushing of direct well, inclined well and horizontal well was established, whichcan be used for sand-flushing parameter design. Corresponding computer program wasdesigned, and foam fluid cyclic process in wellbore was simulated. Through thecalculated example, the relations of annular back-pressure to injection pressure,bottom-hole pressure, volume flux of injection gas under stander condition and injectionfluid were analyzed. Other parameters were fiercely influenced by back-pressure, whichshould be paid more attention to during site application.It can been seen that from field experiments, the program can meet the needs ofdifferent kinds of oil wells, sand-flushing with foam fluid can effectively preventleaking, and set up cycle of oil tube and annular space successfully. After sand-flushingoperation, oil production can be recovered soon, and output of oil wells can be increased. In conclusion, sand-flushing with foam fluid is a kind of effective method to removebottom-hole sand of low pressure oil wells. The thesis results are significant to perfectthe sand-flushing theory with foam fluid and instruct field application.