Research On The Decline Model Of Fracturing Vertical Wells In Tight Sandstone Gas Reservoirs

Compared with conventional gas reservoirs,tight sandstone gas reservoirs have their unique properties.During development,they are often characterized by poor reservoir properties,strong heterogeneity,and complex gas-water seepage laws.In addition,such gas reservoirs often have large burial depths,very complex geological conditions,and low reserves abundance.During the development process,the phenomenon of low single-well productivity and rapid decline in production often leads to difficulties in increasing and stabilizing gas production in this type of gas reservoir.Thus affecting the accurate formulation of development plans.Aiming at this problem,taking the low-permeability and tight gas reservoir in the Linxing block as an example,the influence of local static and production dynamic characteristics on the law of declining production of tight sandstone gas reservoirs in the western Linxing area was studied.The fracturing vertical well seepage model was solved by mathematical methods such as Laplace transform and numerical inversion,and the expression of production over time was obtained.Based on the percolation relationship,the effects of elastic storage volume ratio,channeling coefficient,and pseudo-starting pressure gradient on the decline curve of tight sandstone fracturing straight wells were analyzed.In order to find a more suitable model for fitting the declining production of tight sandstone gas reservoirs,the material balance method,the Arps declining method,and the modern declining method were studied and compared.This method is suitable for the evaluation of gas well decline laws in the west of Linxing.It can reflect the characteristics of gas well percolation and predict the gas well production dynamics.Meanwhile,the Arps decline method can be used as a reference to grasp the approximate decline law of gas wells.