| The structural position of XinChang gas field in western depression of Sichuan basin hasthe characteristics of completed traps, trap development and large reserves.It is judged to be alarge and medium size gas field. The situation of water invasion of Member2of Xujiaheformation in Xinchang gas field is serious after ten years development and the change ofgeological structure.Though the studies of many scholars and research units for Xujiaheformation in Xinchang gas field had obtained many results, development requirements ofXujiahe gas field can’t be satisfied with the results. The gas-water distribution of Xujiaheformation is complex and its controlling factors are not clear.Those problems don’t only affectthe progress of the gas exploration and development serisously,but also decrease the gasmining benefits.This paper,which is based on the study results of predecessor, analysed thefeature of the available well testing, well logging and development performancedata.Researched and analysised the logging feature of pay formation,analysised the feature ofwater chemistry and production performance,divided development unit,researched thetechnologic boundaries and feasibility of drainage gas in member2of Xujiahe formation gasfield and proposed development suggest for the gas reservoirs with water are also bedone.During the studing I got the main understandings as follows：(1) The reservoir geological model of member2of Xujiahe formation in Xinchang gasfield is fractured-porous reservoir which is communicated between low-porosity sandstoneand probable high-porosity sandstone by natural fracture.The development wells in member2of Xujiahe formation gas field can be divided into three fracture units, which includes thefracture unit around X856, the fracture unit around L150and the fracture unit around X10.(2) The types of formation water are all CaCl2, eliminated the impact of desalinationcondensate. There is little change in formation water chemical characteristics. The totalmineralization of member2of Xujiahe formation is between100383.7mg/L and115714.1mg/L.(3) The water output changement of development gas wells can be divided into lessaffected by formation water gas wells, general water invasion wells and special gas&wateroutput wells. On the initial conditions, The network of fracture is filled with gas&water,where gas is in high structure position while water in the low position.(4) The gas geological reserves of X856fracture system is worked out to be88.7×108m3by material balance method. Reservoir geological illustrates that the contiguous large body ofwater does not exist. Development of dynamic analysis shows the distribution of gas andwater are separated into multiple gas and water bodies.Water output belongs to trap-type gasdrive which is passive water drive. It is the only way to reduce waterflooding and developtrap-type gas by discharging water.(5) The fracture system around X856can release the waterflooding of the well X3,X856and X853,and can increase gas production capacity through drainaging water strongly inCX560and CX565which are in low structure position. |
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