A Successful Water Shut Off Treatment in Gas Well of Bassein Field by Polymeric Gel System

Abstract

Worldwide excessive water production in gas reservoirs has always been regarded as one of the most formidable problems, which hampers the productivity of the well to any extent and in the extreme cases may lead to ceasure of the well due to water loading although the reservoir contains sufficient amount of recoverable reserves. The source of water production can be a channel behind casing due to poor cementation, casing leaks, coning, encroachment, water breakthrough and flow through natural and induced fractures. In the process of shutting off /mitigation of unwanted water production, the identification of source of water inflow in the well is the most important step for choosing a correct technique. However, the problem becomes even more complex if multiple mechanisms of water invasion are simultaneously active in the well. There are various mechanical and chemical techniques to deal with excessive water production. The mechanical means provide a seal in the near-wellbore openings. However, most of the time, it is desirable to achieve matrix or small fissure penetration of the sealing material. Among the chemical methods, polymer gels are considered as one of the most commonly applied technique on account of relatively low cost, ease of pumping and ability to penetrate deeper into the reservoir. Bassein is a major gas field in the western offshore basin of India and is producing gas since 1988. The entire structure of the field is a gas cap gas reservoir, which is underlain by very thin oil column and large aquifer and producing gas under partial aquifer drive. The field recovery has crossed 60% of GIIP and presently most of the wells of BC and BE platforms are either producing large amount of water or have ceased to flow due to water loading leading to huge loss of well productivity and making them suitable candidates for water-shut-off treatments. The well BC-2, which was/ had ceased to flow due to water loading, but could not be brought back on production even after mechanical water shut off method was chosen as a pilot well for treatment with deep penetrating high temperature resistant gel system. After gel treatment, the well was put on sustained production along with reduction in water production by 90%. This paper discusses the laboratory studies for polymeric gel optimization, methodology of job design with operation sequence and results obtained from the field.

Physical simulation for water invasion and water control optimization in water drive gas reservoirs

“…Numerous efforts have been made regarding gas reservoir water invasion control by researchers in the oil and gas industry. There are currently three main types of water control countermeasures, i.e., water drainage, gas well deliquification, and water shut-off [8][9][10] . Water shut-off is performed to reduce the permeability of fractures by injecting chemical agents, such as gelant, into them, thus preventing water invasion.…”

Study on Selective Water-blocking Agent for Temperature and Salt Resistance, Water Blocking, Air Permeability

“…At present, the common water plugging system includes polymer, polymer gel, foam gel and so on. The gel system formed by Mattey et al [4] by combining polymers with organic cross-linker can cope with the water production problem caused by channeling and fracture communication, but the effective time is short and the long-term water plugging cannot be achieved. He [5] et al and Wang [6] et al believe that although foam gel can achieve selective water plugging through bubble deformation, its erosion resistance is poor due to its poor stability and other problems.…”

Physical Simulation for Water Invasion and Water Control Optimization in Water Drive Gas Reservoirs

“…Numerous efforts have been made regarding gas reservoir water invasion control by researchers in the oil and gas industry. There are currently three main types of water control countermeasures, i.e., water drainage, gas well deliquification, and water shut-off (Hearn 2010;Yang et al 2013;Mattey et al 2017). Water shut-off is performed to reduce the permeability of fractures by injecting chemical agents, such as gelant, into them, thus preventing water invasion.…”