Research On Dynamic Analysis Method And Application Of Water Drive Gas Reservoir

At present,most of the gas reservoirs developed in our country are different degrees of water drive gas reservoirs.Taking the Sichuan basin as an example,there are about 500 gas reservoirs structures,which water-driven for nearly 250.Gas reservoir with the development of the continuous bottom of the water continued immersion.On the one hand,the gas water two-phase flow will have bad effects on the production of the gas well,especially after the water is seen in the gas well,the output will drop sharply.On the other hand,the method of Production decline analysis method is widely used in water-driven gas reservoirs,but these methods are based on closed elastic theory and can not be used in dynamic analysis of water-driven gas reservoirs.Therefore,it is very important to carry out the dynamic analysis method of water gas reservoirs,which is of great significance to the detailed description of gas reservoirs,reserve forecast and development effect evaluation.Based on the theory of seepage mechanics,this paper establishes a set of fitting method for the dynamic analysis of water reservoirs,and obtains the following conclusions and cognition:(1)The seepage model of "Step-type" water vaporization reservoir and the seepage model of "Ramp-type" water vaporization reservoir are established.(2)The basic model and the boundary flow model are Laplace transformed and solved,and the constant pressure production solution and the fixed pressure solution are obtained.(3)the "Ramp-type" water flooding/"Step-type"water flooding gas analysis combined with the theory of decreasing reservoir model and Fetkovich,are suitable for water drive gas reservoir dynamic analysis Fetkovich decline analysis method;The Fetkovich characteristic curve of water drive gas reservoir is drawn by using VB programming.There are four flow stages for the Fetkovich typical curve of the waterflooding reservoir.Curve characteristics are mainly affected by well control radius,water invasion stability time and water intrusion stability flow.(4)The results show that the water-driven gas reservoirs can be used to evaluate the material balance equation of water-driven gas reservoirs.Based on the Blasingame descending analysis theory,the decreasing graph of water drive gas reservoir is obtained,and a set of Blasingame analysis method is applied to the dynamic analysis of water drive gas reservoir.(5)The results show that the reliability of the method is proved by comparing the results of the dynamic analysis software with the dynamic analysis of the typical wells and the dynamic analysis of the two typical wells.It is concluded that the typical curves obtained in this paper are in good agreement with the actual production.This method not only evaluates the parameters of single well control reserves,permeability,and control radius,but also can quantitatively evaluate the parameters such as water invasion time,water invasion intensity,water body size and so on.This method provides a theoretical basis for the dynamic interpretation and efficient development of the edge water reservoir.