Effect of Water Blocking Damage on Flow Efficiency and Productivity in Tight Gas Reservoirs

Abstract

Tight gas reservoirs normally have production problems due to very low matrix permeability and significant damage during well drilling, completion, stimulation and production. Therefore, they might not flow gas at optimum rates without advanced production improvement techniques. The main damage mechanisms and the factors that have significant influence on total skin factor in tight gas reservoirs include mechanical damage to formation rock, water blocking, relative permeability reduction around wellbore as a result of filtrate invasion and liquid leak-off into the formation during fracturing operations. Drilling and fracturing fluids invasion mostly occurs through permeable zones or natural fractures and might also lead to serious permeability reduction in the rock matrix that surrounds the wellbore, natural fractures, or hydraulic fracture wings. This study represents evaluation of water blocking damage in tight gas formations, and the influence on core flow efficiency and well productivity. Core scale reservoir simulations were carried out based on a typical Western Australia tight gas reservoir in order to numerically model liquid invasion during overbalanced, balanced and underbalanced drilling, and the effect on gas production in clean-up period. The simulation results describe how water blocking reduces near wellbore permeability and affects well productivity and gas recovery from tight gas reservoirs.

Rate enhancement in unconventional gas reservoirs by wettability alteration

“…Therefore, hydraulic fracturing is commonly used to stimulate wells in coal seam, shale and tight gas reservoirs (Wang et al, 2012). For reservoirs with very low permeability, fracturing and drilling fluid leak-off along with capillary end effect leads to an increase of water saturation in the near wellbore or fracture-wall regions (Xie et al, 2009;Bahrami et al, 2011;Odumabo et al, 2014). Fluid invasion into the reservoir is greatly affected by the contact angle (Li et al, 2014).…”

“…This water entrapment is referred to as water blockage. A few studies have been conducted on water block clean-up (Mahadevan et al, 2007(Mahadevan et al, , 2009 and the long-term effects on production (Bahrami et al, 2011). One of the most effective methods to reduce water retention is wettability alteration (Barenblatt et al, 1990).…”

Effect of Wettability Alteration on Productivity Enhancement in Unconventional Gas Reservoirs: Application of Nanotechnology

“…However, in such reservoirs with naturally low permeability, the capillary effect is significant if compared to the viscous effect. The capillary end effect as well as loss of fracturing and drilling fluids will lead to an increase of water saturation near the wellbore or fracture faces (Xie et al, 2009;Bahrami et al, 2011;Odumabo et al, 2014). Fluid invasion and water saturation in wellbore vicinity are sensitive to the contact angle of rock surface (Li et al, 2014).…”

“…It is referred to as water blockage. Some research has been performed on water block clean-up (Mahadevan et al, 2007) and the long-term effect on production (Bahrami et al, 2011). One of the most effective methods to reduce water retention is wettability alteration (Anderson, 1987;Ford et al, 1988).…”

Evaluation of Microwave Heating on Fluid Invasion and Phase Trapping in Tight Gas Reservoirs

“…Tight gas reservoirs are susceptible to formation damages such as phase trapping and clay swelling due to small pore diameter, which is less than micron in average (Bahrami et al, 2011). Phase trapping is consequence of interaction of capillary pressure and relative permeability phenomena in formation(D. Bennion, Thomas, Schulmeister, & Romanova, 2006).…”