Analytical interference testing analysis of multi-segment horizontal well

Abstract

Most interference-testing analysis of horizontal well ignores fluid flow in and out of the horizontal observation well and represent it by a point. Moreover, even if the observation well is considered to produce fluids during the field test, the production distribution is assumed to be uniform along horizontal wellbore. In fact, production logging tests have shown that only partial horizontal segments are productive and the production contribution is non-uniform along horizontal wellbore.The aim of this paper is to develop a novel interference testing model of a multi-segment horizontal well (MSHW). Analytical solutions are derived to incorporate the interference of injection wells and consider the effect of non-uniform production on pressure response of the MSHW. There is no need to shut in the horizontal observation well, and the horizontal well is composed of multiple segments with arbitrary rate, length, skin, etc. The type cures of the interference testing model are developed to discuss the effect of both active wells and observation well on pressure behavior (e.g., injection rates, well spacing, rate distribution of horizontal observation well, number and length of horizontal producing segments, permeability anisotropy, horizontal wellbore location in vertical and horizontal plan). Results indicate that the pressure and pressure derivative curves move down during the middle and late flow regime due to the effect of surrounding injectors. The pseudo-radial flow regime may disappear due to the interference caused by adjacent wells. The interference flow regime (IFR) may stabilize at 0.5*(1-ΣqjD) on pressure derivative curve when the total injection rates are less than the production rates. The pressure-derivative curve shows the similar characteristic with bottom-water drive when injection rates are much higher than the production rates.The proposed model is more realistic and enables us to better understand the interference of injection wells when the horizon observation well is open to produce. With the help of interference tests, this model can be applied to evaluate the communication between wells, diagnose the water-inflow direction, and optimize well pattern, which ensure the success of a secondary or an enhanced recovery process.