Modeling of Borehole Zone Influence on Stimulation Efficiency of Gas Production

During development of gas field one of the most serious problem is a well production decline due to borehole zone properties deterioration. For well production recovery there are a lot of various methods. And hydrochloric acid treatment received a large area of implementation. However it is a common practice that actual well production increase is lower then expected. This fact has a negative influence on the economic indexes and may bring to loss of profit. Estimation of treatment efficiency demand knowledge of such impotent value as relative increase of gas production. Previously believed that after borehole zone treatment the borehole zone permeability can change only trough cleaning and seam dissolution. But special research showed that after borehole zone treatment the compressibility of the seam may change too. In connection with above we build a mathematical model of gas filtration toward the well with complex borehole zone witch take into account both blockage and compressibility. In case when we consider borehole zone blockage only the filtration equation has analytical solution in terms of integral function. But when we account compressibility of the seam a numerical methods are needed. We considered relative permeability of gas as product of two functions k(r,p)=A(r)*f(p), where function A(r) simulate a borehole zone blockage and f(p) simulate compressibility of the seam. Previously function A(r) was considered as fully modeling. There are various formulation of its view such as linear function, quadratic function, root function and constant function. But all of these formulations haven’t a physical validation. We suggest using probable convolutions method with Gaussian kernel for well-logging data interpretation and definition redial borehole zone filtration properties. In our previous papers showed that a view of A(r) function greatly influence on well production. That is why an adequate definition of this function is very impotent. Using this model we researched dependence of hydrochloric acid treatment efficiency from such parameters as radius of acid penetration, permeability on the well, coefficient of compressibility. And we offered technological scheme of treatment efficiency prediction.