The Effects of Fracture Cleanup on the Productivity of Gas Condensate Systems

Abstract

fax 01-972-952-9435. AbstractThe performance of fracturing treatments has been an issue for over fifty years and considerable effort has been devoted to improve its prediction performance. However, the effect of cleanup in tight gas-condensate reservoirs where fracturing considered as the most common well stimulation technique, has not been fully investigated for these low IFT systems. The performance of cleanup operation heavily depends on the mobility, i.e., viscosity and relative permeability (k r ), of fracturing fluid compared to those of gas and condensate. This determines the extent of invaded zone near the wellbore region and the ease with which fracturing fluid is removed during the back-flow operation.In this work, measured values of permeability, singlephase inertial factor and k r of a propped fracture and those of a tight reservoir rock have been used to evaluate the performance of fracturing treatments. ECLIPSE 300 compositional reservoir simulator, which includes our inhouse k r correlations accounting for coupling (i.e., the increase of k r as velocity increases and/or IFT decreases) and inertial (i.e., the reduction of k r as velocity increases) effects, was used to develop realistic fractured flow systems. A sensitivity analysis on the impact of different hydraulic fracturing fluid, fracture characteristics and reservoir fluids on the productivity of a single-well model were conducted resulting in some practical guidelines.The results indicated that the performance of 300 cp high viscosity fracture fluid is better than that of 10 cp low viscosity fluid, due to a lower penetration depth. When k r of oil based fracturing fluid is improved, compared to that of water based, the back flow of fracturing fluid is facilitated especially for the 10 cp low viscosity fluid. Presnece of condensate facilitate the backflow of fluid, hence, cleanup efficiency is better for richer fluid systems.

Method for C5+ Content Estimation in Produced Gas Condensate (Russian)

“…Для фазовых проницаемостей в трещинах ГРП зачастую используются две прямые линии, тем не менее, в литературе отмечается, что это упрощение совершенно необязательно является хорошим допущением (Jamiolahmady et al, 2007). Поскольку, это так же согласуется с личным опытом авторов (Butula et al, 2005), относительные фазовые проницаемости для газа и конденсата k r g и k r o в трещине ГРП были рассчитаны как квадратичные функции насыщенности S g , S o соответственно:…”

Optimization of Chock Valves for Fracture Clean-up in Tight Gas Condensate Reservoirs

“…The efficiency of clean-up in tight gas condensate reservoirs has a tremendous effect on the productivity of gas-condensate wells. 4,5,6 Fracture-fluid clean-up efficiency is highly related to proppant volumes, multiphase flow, proppant crushing, polymer filter cakes and yield stress of concentrated gel in fractures. 7,8 Recommendations to improve fracture clean-up efficiency have been made in previous work, 9 including chemical additives, 10,11,12 water evaporation, 13 coated fracturing proppants, 14,15 and microwave heating.…”