Study On Reasonable Gas Production Rate Of X Water Drive Gas Reservoir

Water drive gas reservoirs cover more than half reserve of gas reservoirs under development in our country. Most water drive gas reservoirs with strong heterogeneity, strong aquifer and high gas production rate present water invasion, to some extent, which restricts the development of the reservoir. Therefore, considering various factors, flow law of aquifer should be studied to determine the gas rate, prevent earlier waterflooding of the gas reservoir, and ensure efficient development.For unclear understanding of proration limit and its influence on recovery of the blocks in one offshore water drive gas reservoir X, study on aquifer flow law, single well proration limit, main influence factors on recovery as well as proration of the target reservoir has been conducted, based on the geological features of the target reservoir and survey of global gas production rate and development. Main achievements are shown below:(1)Survey on global similar water drive gas reservoirs shows:average gas production rate of this kind of reservoir is 5%-6%, with recovery factor of 60%-75%. Gas production rate should be kept to a reasonable value at the initial stage, and the rate should be adjusted after water breakthrough to keep the reservoir produced at a stable state.(2)With the analysis method of water breakthrough characteristics, water breakthrough type of the target reservoir has been studied. The analysis of the geological and production status show that the direction of water invasion of CHX1 is bottom water encroachment, and CHX3 is the south and north edge water encroachment. And the analysis on the water invasion strength based on a variety of means indicates that the reservoir is a medium-strong elastic water drive. Current water invasion amount of the block CHX1 and CHX3 are calculated on an unstable water invasion model,70.93×104m3 and 198.22×104m3 respectively.(3)Calculation and analysis of absolute open flow rate (AOF), critical liquid carrying rate and critical rate of the studied reservoir show:the reasonable rate of the well is 10%-30% of the AOF flow rate; there may be liquid loading in the well A10 for the close of the production rate to critical liquid carrying rate, and production rate of other wells are higher than the late; wells where production rate are higher than critical production rate have produced water; while wells with production rate lower than critical rate are in stable state.(4)Mechanism analysis of sectional model shows:larger the gas production rate, lower the recovery factor; higher the height of water avoidance in the bottom water model, higher the recovery factor; higher the perforating level of the edge water, higher the recovery factor. (5)Numerical simulation model has been established, as well as history match. Based on gas reservoir proration limit, several programs have been made to determine the reasonable gas production rate of CHX1 2% and CHX3 4%.