Research On Water Invasion Characteristics Of MX Gas Reservoir

For water-bearing gas reservoirs,formation water intrusion into the formation will result in bottom-hole fluid accumulation,even water flooding and shutdown of gas wells,reduce the recovery of gas reservoirs,increase the difficulty of development,and restrict the rational and efficient development of gas reservoirs.If the water invasion performance can be predicted objectively and timely,and the water invasion characteristics of water drive gas reservoirs can be accurately understood,the gas well working system and water control measures can be reasonably selected to improve gas reservoir recovery.Therefore,relying on the cooperation project of Chuanzhong Oil and Gas Mine of PetroChina Southwest Oil and Gas Field Branch,this paper studies the water invasion characteristics of MX gas reservoir,paving the way for rational and efficient development of MX gas reservoir.Starting from the water production characteristics of MX main gas reservoir,the saturated condensate water content of 46 gas wells is calculated by using the fluid phase theory.Combined with production water-gas ratio analysis,hydrochemical characteristics analysis and Gp?Gw relationship curve analysis,a comprehensive identification system for water production types of MX gas reservoir is established,and the water production quality of 46 gas wells is judged.The water production time and water production types of 13 water-gas wells producing formation are quantitatively evaluated.Based on the analysis of pressure and production decline law of 46 gas wells,the influence degree of water production on production performance of gas wells is quantitatively evaluated;water invasion intensity of gas reservoirs is qualitatively evaluated by pressure drop method,nomograph method and apparent geological reserves method;unstable water invasion method of Hurst-van Everdingen,non-linear material balance method and improved water invasion volume coefficient method are compared and analyzed.The method for calculating water influx in MX main gas reservoir is screened out,and the water influx and water influx rate in well area and different types of gas wells are calculated and analyzed.The productivity evaluation method for water-producing gas wells in MX main gas reservoir is established.The initial productivity evaluation and current productivity evaluation of 46 gas wells are carried out,and the influence of water influx on gas wells productivity is quantitatively evaluated by using the method of flow material balance and modem technology.Production decline analysis method and model method are used to calculate single well controlled reserves of gas wells,determine dynamic reserves of gas reservoirs,and quantitatively evaluate the impact of water invasion on single well and gas reservoir controlled reserves.The following understandings are obtained:(1)Formation of MX gas reservoir development performance tracking and evaluation technology;Sr2+ early warning method was proposed for the first time to solve the problem that gas wells can be identified after water invasion;the study found that the production capacity of formation water-producing gas wells is significantly lower after formation water production;the production capacity of formation water-producing gas wells is significantly lower than that of non-production formation water-gas wells during the whole production process;Water invasion has a great influence on gas well production.(2)Screening out the calculation method of water invasion suitable for MX gas reservoir;from the point of view of well area,formation water is not active and has little influence on well area;since 2018,the increase of water invasion of gas wells with different water invasion types has slowed down in varying degrees,the water invasion replacement coefficient has decreased,and the water invasion rate has slowed down obviously;but the water invasion replacement coefficient of MX18,11 and 204 wells is still large,and the pressure of water prevention and control is still large.It is necessary to adopt the method of combining water carrying production of water producing wells with production control of adjacent wells.(3)The empirical formula of "improved point method,for MX gas reservoir is deduced,which can provide support for rapid evaluation of gas well production.MX gas reservoir is dominated by high productivity wells,with an initial open flow rate of 15966.07*104m3/d;water invasion has a greater impact on the productivity of water-producing gas wells and a smaller impact on the productivity of wellbore areas.(4)The performance of dynamic control reserves in MX gas reservoir is that there are great differences in dynamic control reserves of different gas wells(4*10sm3-130*108m3),andthe average dynamic reserves of wells(55*108m3)are large.Water invasion has great influence on dynamic control reserves of water and gas wells in production formation,but little influence on the dynamic control reserves of the whole gas reservoir.