A New Solution To Restore Productivity of Gas Wells With Condensate and Water Blocks

Abstract

Summary During production from gas-condensate reservoirs, significant productivity loss occurs after the pressure near the production wells drops below the dewpoint of the hydrocarbon fluid. Many of these gas reservoirs also have some water accumulation near the wells. This adds significantly to the total liquid blocking. Experiments were conducted using both outcrop sandstone and reservoir cores to measure the effect of liquid blocking on gas relative permeability. A chemical treatment was developed to reduce the damage caused by condensate and water blocking. The treatment is composed of a fluorinated material delivered in a unique and optimized glycol-alcohol solvent mixture. The chemical treatment alters the wettability of water-wet sandstone to neutral-wet and increases the gas relative permeability. The increase in gas relative permeability was quantified by comparing the gas relative permeabilities before and after treatment. Improvements in the gas relative permeability by a factor of approximately two were observed. The alteration of wettability after the chemical treatment was evaluated by measuring the USBM wettability index of treated reservoir cores. Measurements show that a significant amount of the surfactant is adsorbed on the rock surface, which is important for the durability of the treatment. Many attempts have been made to develop effective chemical treatments to mitigate the damage caused by condensate and/or water blocking with little success until now under realistic reservoir conditions. Using inexpensive, safe, and effective solvents was one of the keys to the success of our new approach. Other researchers have mostly tried reactive materials that are subject to complications in downhole applications. We use a nonreactive, nonionic polymeric surfactant that has none of these problems and is robust across a wide range of temperature, pressure, permeability, and brine salinity. We have developed a chemical treatment for liquid blocking that shows great potential to increase production from gas-condensate wells. Compositional simulations indicate that the economics of this treatment process is likely to be very favorable.

Gas Condensate Banking: A Review of the Phenomenon, Accumulation, Mitigation Methods, and New Breakthrough

“… Using chemical treatment to modify the rock surface wettability from liquid-wet to neutral-wet (6,14).  Limitation: still at research stage (15,16).…”

Benchmarking Project Level Engineering Productivity / Inžinerinės Veiklos Našumo Lyginimas Projektų Lygmeniu

“…Although many approaches have been adopted for performance evaluation in the various industry sectors such as software industry, manufacturing industry, and even the construction industry (Bang et al 2010;Benestad et al 2009; de Aquino, de Lemos Meira 2009;Fleming et al 2010;Issa et al 2009;Niu, Dartnall 2010;Ren 2009;Yang, Paradi 2009), there are limited suitable approaches for the development of a project level engineering productivity metric. The Project-Level Productivity (PLP) index was developed by Ellis and Lee (2006) for monitoring multidiscipline daily labor productivity.…”

Mitigation of the Effects of Condensate Banking: A Critical Review

“…Barnum et al (1995) found a dramatic decline in the production rates and hence reduction in gas recovery for wells with a permeability-thickness product of less than 1,000 md-ft. Takeda et al (1997) claimed that gravity force and interfacial tension are important factors in determining the relative permeability, and hence the buildup of condensate, around the wellbore. Barnum et al (1995) reported that the higher the well capacity (well capacity is the kh product, where k is the rock permeability and h is the reservoir thickness, and is a measure of the reservoir quality), the less the impact of the condensate banking on the productivity of wells drilled in condensate reservoirs. Simulation and laboratory studies have indicated that condensate saturation around the wellbore may reach 70% (Marokane et al 2002).…”

“…These models showed that the liquid condensation and accumulation around the wellbore results in a reduction in gas permeability and in a significant decline in the production rates of wells (Hinchman and Barree 1985;Clark 1985;Barnum et al 1995;Ahmed et al 1998). Barnum et al (1995) found a dramatic decline in the production rates and hence reduction in gas recovery for wells with a permeability-thickness product of less than 1,000 md-ft. Takeda et al (1997) claimed that gravity force and interfacial tension are important factors in determining the relative permeability, and hence the buildup of condensate, around the wellbore. Barnum et al (1995) reported that the higher the well capacity (well capacity is the kh product, where k is the rock permeability and h is the reservoir thickness, and is a measure of the reservoir quality), the less the impact of the condensate banking on the productivity of wells drilled in condensate reservoirs.…”