Formation Heat Treatment Process by Combustion of Gases Around the Wellbore

Abstract

Formation damage can occur at any stage during the lifetime of a well. Operations such as drilling, completion, workovers, and stimulations expose the formation to fluids that may be almost all incompatible with the formation and its original fluids. These situations can cause a reduction in the permeability of the formation around the well bore, and/or a reduction in the production of fluids. A detailed description of the formation damage mechanisms is presented in the literature (1,2) .New methods have been developed to counteract formation damage and, in doing so, improve injectivity. One of these methods is formation heating. The aim of formation heating is to increase the temperature of the formation around the well-bore in order to improve the hydrodynamic conditions in the near wellbore area. A popular field application technique of formation heating is the utilization of a down-hole electrical heater. The heater is placed as close as possible to the target zone, and an inert gas, such as nitrogen, is co-injected through the annulus. Using this method, the temperature of the injected gas may rise to as high as 800˚ C before entering into the formation (3) . The big inconvenience of this method is the large energy requirements associated with it.Another remediation technique is the use of a down-hole gas burner. Using this method, hot flue gases are injected into the formation. The main concern with down-hole gas burners is the lack of combustion control, corrosion, and the requirement of specialized and expensive equipment (4) .The utilization of a radio frequency (RF) antenna, as a heating system for enhanced oil recovery, is another remediation technique (5) . Electrical heating tools and their applications can be divided in into three categories: (1) low frequency currents are used in resistive/ohmic heating. (2) high frequency currents are used in microwave heating methods. (3) induction tools utilize electrical energy to inductively heat the reservoir through the ferro-magnetic casing (6,7) . Using these techniques, the increase in temperature of the formation is not enough to vapourize water and, as a result, their application will only result in heating the oil in the near-wellbore area.A technique called combustion stimulation was proposed and used in the 1960s (4,8,9) . Using this method, a combustion front is initiated in the well-bore by means of a heater or burner, and the front is propagated into the formation to a distance of 3 m to 6 m. As a result, the formation in this zone is reduced to clean, burned sand, offering very little resistance to fluid production.Research on the combustion of gases in porous media at the University of Calgary is being carried out with the potential of applying this concept to the process of formation heating. Gaseous combustible mixtures may be injected in a uniform distribution over the sand face, ensuring a uniform treatment, and allowing for a uniform modification of structural and fluid mechanical properties. In the field, this process can be initiated by t...

Thermal simulation of shale gas recovery involving the use of microwave heating

“…The authors argued that , the combination of hydraulic fracturing and horizontal drilling has allowed more gas to be easily extracted from shale, however its impact on the environment suggests that alternative techniques needs to be explored. Similar studies also suggests thermal stimulation of shale gas reservoirs can result in effective permeability improvement just like in oil shales (Busch and Amann-Hildenbrand, 2013;Sanmiguel et al, 2002). According to Jamaluddin et al(2000) thermal treatments in tight gas reservoirs enhances the permeability of the formation by vaporizing the capillary blocked water, dehydrating the clay bound water and creating thermally induced micro-fractures.…”

Diffusive Effects on Recovery of Light Oil by Medium Temperature Oxidation

“…The temperature of the medium is bounded by the boiling point of the liquid and, thus, remains relatively low. There are numerous references indicating that gas-phase reactions in porous media in itself are important (Bakry et al 2011;Pereira et al 2009;Sanmiguel et al 2002;Zheng et al 2010). Gas-phase reactions can be important for HPAI .…”

A Fully Coupled Numerical Model for Microwave Heating Enhanced Shale Gas Recovery

“…Formation heat treatment (FHT) is a process with great potential in enhancing gas production from unconventional oil/gas reservoirs [1,[12][13][14]. Different heating technologies, such as an electrical heater, hot water flooding, high-temperature steam, in-situ combustion, and electromagnetic heating (microwave/radio frequency) and so on, were applied to the oil and gas industry [4,6,[15][16][17].…”

“…Different heating technologies, such as an electrical heater, hot water flooding, high-temperature steam, in-situ combustion, and electromagnetic heating (microwave/radio frequency) and so on, were applied to the oil and gas industry [4,6,[15][16][17]. It is asserted that the heat treatment of shale gas reservoirs can enhance permeability in a similar way for oil shales [3,13]. The combustion and pyrolysis can remove organic matter and decompose minerals from shale and further increase shale matrix permeability [4,6].…”

“…The maximum temperature increment could reach around 650 • C. Gas-phase combustion for tight gas reservoirs may be an alternative for FHT. The temperature within the porous media can reach above 600 • C [12,13]. Meanwhile, the combustion enhancing recovery of shale gas was investigated through numerical simulations [3] and experiments [4,6].…”