Applied gas-well-testing data analysis considers that the nonlinear diffusivity equation becomes linearized by the pseudopressure function and by assuming the gas viscosity-compressibility product constant throughout the test history. This approach is justified for small pressure drawdowns only. This condition is seldom met in low-permeability gas reservoirs, whether the wellbore is fully perforated or not. This paper considers a restricted-entry vertical well in a homogeneous anisotropic infinite reservoir producing at constant-gas-flow rate, which, surprisingly, has not been the object of much research, either by numerical simulation or by analytical means. In this work, the Green's function (GF) method is used to rewrite the usual partial-differential formulation as a multidimensional integro-differential equation for the pseudopressure function that rigorously accounts the gas viscosity-compressibility product change. From there, an approximate explicit solution for a uniform-flux boundary condition is derived, which shows that the pseudopressure solution is given by the correspondent restricted-entry well slightly compressible (i.e., liquid) solution, plus a corrective term that handles the gas viscosity-compressibility product variation with pressure. Comparison with a commercial numerical simulator shows that the uniform-flux approximate solution is very accurate. Results are presented for a few perforation lengths and positions, with and without vertical anisotropy. It is shown that during the perforation-radial (early-time) and finalradial (late-time) flow regimes, the corrective term becomes constant. Their magnitudes, however, are quite different; during the perforation-radial flow regime, the corrective term is quite large compared with the one seen at long times. Thus, the pseudopressure derivative with respect to the natural log of time exhibits the same restricted-entry behavior observed in oil reservoirs. By averaging the uniform-flux solution over the open interval, an infiniteconductivity approximate solution for the wellbore pseudopressure is presented, which shows a very-good agreement with results obtained from a finite-difference simulator. 2016 SPE Journal 1 1.E-00 1.E-1 1.E+0 1.E+1 Case A -This work -m wD Case B -This work -m wD Case A -Finite difference -m wD Case B -Finite difference -m wD Case A -This work -m wD Case B -This work -m wD Case A -Finite difference -m wD Case B -Finite difference -m wD Case A -This work -m wD Case B1 -This work -m wD Case B -This work -m wD Case B2 -This work -m wD Case A -Finite difference -m wD Case B1 -Finite difference -m wD Case B -Finite difference -m wD Case B2 -Finite difference -m wD 1.

In most of its deepwater Campos Basin oilfields, Petrobras' strategy has been to develop the water flooding systems using horizontal gravel packed wells. Both drilling and gravel pack operations are only possible through the presence of a filter cake, formed on the formation face during the drilling process. Nevertheless, that film becomes an impediment to injection and must be removed to obtain good injectivity.Special tools were developed to perform acidizing jobs, in one trip, just after the gravel packing operation. However, there were few alternatives to correct any eventual acidizing lack of performance, besides using coiled tubing and straddle packers, something that usually takes too much time.Recently, a pulse-rotating jet tool system was applied in a well that could not be treated after the gravel pack operation. The treatment, which is simpler and faster than those carried out with straddle packers, was performed in two stages: the first, using just HCl, and the last one, using mud acid.The subsequent formation test performed after the HCl treatment showed a high skin v alue and an unacceptable injectivity index, due the need to keep the reservoir pressure above the bubble point. Even so, the test data in association with reservoir simulation, according with the field geology, showed that there was fluid injection throughout the entire horizontal section. Therefore, it was decided to perform a mud acid treatment, again, using the pulse-rotating jet tool system. This time, a second formation test indicated an excellent injectivity index, confirming the pulse-rotating jet tool system effectiveness and creating perspectives for the application of this technique in future operations. This paper will describe the technique, job details and the results obtained for this particular operation, which may be applied in other similar offshore environments.