Fracturing Considerations in Mid Permeability Gas Condensate Formations

Abstract

Hydraulic fracturing can be widely used for stimulation of gas condensate reservoirs not only in order to improve the Productivity Index (PI) of the well, but also to minimize the condensate banking effect and maximize recovery, therefore ultimate impact the economic success of the production enhancement operations.Understanding the parameters affecting adequate propped fracture geometry is critical to the process. While none or limited influence can be exercised on the hydraulic fracture geometry from the reservoir side, the fracturing materials and the pumping technology at large, now on the disposition to the frac design engineer have ever been improving and will define the level of achievement.The general statement valid for mid perm reservoirs of high pore pressure and relatively high reservoir temperature, that it is very important to create a fairly long and clean, conductive propped fractures is not sufficient, in reservoirs where condensate banking represent a potentially important pressure loss.To counter the effects caused by pressure depletion below dew point that are resulting in multiphase flow and condensate bank creation in the reservoir, maximum conductivity fractures are designed. Further, depending on the drawdown and induced flow rate to the wellbore, non-Darcy effects, flow convergence and proppant damage can be potentially encountered; hence, fractures designed under the concept of "maximizing conductivity" will additionally decrease the well productivity decline.The analysis presented in the paper was based on a combination of data obtained from field measurements, analytical calculation and numerical simulations, modeling in all details the key processes defining the productivity gas condensate reservoir. The first results obtained indicate that the placement of extremely conductive fractures has a definite advantage in both productivity as well as in recovery of liquid hydrocarbons.To conclude -it can not be overemphasized that ensuring good conductive fractures that will ensure minimum pressure drop from multiphase, or non-Darcy flow is critical. Excellent wellbore connectivity by wide and conductive near wellbore fracture paths and maximizing inflow area and minimizing convergence flow effect is not to be underestimated too. The fracture design has to ensure this environment in the initial production phase as well as in years to come when reservoir pressure drop is expected and higher effective stress, proppant crush, fines migration and embedment, are placing additional strain on maintaining the fracture conductivity.