Study On Reasonable Proration For Typical Layers Group Of Sebei Gas Field

In the development of unconsolidated sandstone gas reservoir,there are many problems,such as stress sensitivity,water production,sand production and bottom hole liquid loading.Thus,the deliverability of gas wells can be greatly reduced,resulting in economic losses.The rational distribution of production can effectively restrain the above problems,so it is very important to make reasonable proration in the development of unconsolidated sandstone.In this paper,unconsolidated sandstone gas reservoir as the research object,on the basis of previous theoretical research and measured data of the gas reservoir,in the typical layer group of Sebei gas field reasonable proration oriented,starting from the seepage mechanism of influence factors of gas well deliverability and the pressure change characteristics of gas well and layer group,completed the following main work:(1)The reasonable logging interpretation of the deliverability test data of 88 gas wells in the typical layer group of Sebei gas field,and the analysis of the seepage mechanism of the four main factors affecting the gas well deliverability.(2)The evaluation of dynamic geological reserves of gas well and four typical layer group;the analysis of gas well and layer group pressure variation characteristics;the evaluation of gas reservoir rate-maintenance capability.(3)Research on the optimization of Sebei gas well proration and corresponding production calculation analysis;the production index with those proration of III-2 and III-3 layer group predicted by numerical simulation.Through the above research,the main conclusions and understanding as follows:(1)The main factors that affect the gas well deliverability are stress sensitivity,water production and sand production,and interlayer interference in commingling production gas well.The conventional deliverability analysis method is not applicable to the Sebei gas wells,and the interpretation results are often large.(2)Four typical layer group reserves potential and potential tapping measures are different.(3)During the process of development,the main controlling factors of formation pressure distribution and variation law of each formation include:the time of putting into production,the proration of gas well,the density of well pattern,the mining intensity and the size of the edge water and the degree of the connection of edge water.(4)Due to the high single well proration with large liquid carrying capacity can effectively prevent bottom hole liquid loading on deliverability of gas wells and recoverable reserves of the damage,the reduction of abandoned formation pressure by pressurization mining can effectually improve the rate-maintenance period and the development effect of Sebei gas field.(5)The Sebei gas well annual decline rate of rate-maintenance capability are 10.43%,the main controlling factors are types of water and well.(6)The optimization of gas well proration in the Sebei gas field needs to consider gas well deliverability,the layer energy,the formation of the bottom hole liquid loading,the formation sand production,the bottom hole sand loading sand and the erosion on wellbore,but the last one has almost no effect on Sebei gas wells.The main innovation of this paper:based on the analysis of the seepage mechanism of gas well deliverability and the combination of the formula method and the back pressure test method,this paper puts forward the modified formula to evaluate the deliverability of the Sebei gas wells;this paper presents a method that considering the weight of single well controlled reserves in the volumetric method reserves to calculate the average formation pressure,and calculates the dynamic reserves of single gas well and layer group by the combination of pressure-drop method and the correction coefficient of binomial deliverability equation.this paper proposes a method with mathematical statistics to analysis the rule of decline rate of rate-maintenance capability;the proration of layer group combines with the gas well deliverability,the layer energy and the optimized single well proration.