First Successful Filtercake Damage Removal Treatment Utilizing In-situ Nitrogen/Heat Generating system for Relatively Heavy Oil Wells

Abstract

Nitrogen/heat generating system (N/HGS) is a thermal-chemical method comprising huge amounts of heat and nitrogen gas generated by reaction between two nitrogen-containing aqueous salts, ammonium chloride and sodium nitrate. The inherent properties of this system make it a good additive in matrix acid stimulation and clean-up treatments for heavy oil wells. The generated heat tends to reduce the oil viscosity, thus enhancing oil mobility while the generated nitrogen gas will reduce hydrostatic pressure of the oil column. Both actions will help the reservoir to better cleanup. Lab results showed that N/HGS was effective in removing oil-based mud filtercake damage. Application of N/HGS cleanup fluid in HP/HT filter press cell was associated with an increase in pressure of more than 100 psi and in temperature of nearly 40°C. An optimized N/HGS formulation was very effective on filtercake removal; nearly 81% of flow efficiency was obtained. The N/HGS formulation contains in addition to the basic nitrogen-containing salts an organic acid, an emulsion breaker and a viscosity reducer. The organic acid, acting as a reaction catalyst in N/HGS, is also proposed to dissolve bridging material presents in filtercake, calcium carbonate. Application of this system, for first time in Saudi Arabia, to remove oil-based filtercake damage from a sandstone horizontal well was very successful. The N/HGS components were pumped in a way to be mixed in the wellbore of the horizontal section. Coiled tubing was used to pump one component while the other component was pumped through the annulus. The reaction of N/HGS components was associated with generation of huge heat as detected by the Distributed Temperature Survey (DTS) which showed that reservoir temperature increased from 153 to more than 300°F. Following the N/HGS treatment, the dead well was able to produce naturally with a competitive production rate compared to offset wells treated with conventional clean-up fluids.

Thermally Activated Nitrogen/Heat Generating Reaction: A Kinetic Study

“…As promising techniques, in situ nitrogen gas/heat generation reactions have been given more attention by several researchers nowadays. In situ generated N 2 can be utilized to provide better foam quality for different field applications, including well cleanout, enhanced oil recovery (EOR), and fracturing operations. − Therefore, understanding the rate of nitrogen gas generation is crucial to design required foam quality under specific field conditions. In this study, the reaction kinetics of a thermally activated NH 4 Cl/NaNO 2 reaction was studied.…”

Study of Chemical Additives for Optimization of Binary Systems Used for Downhole Thermochemical Treatment of Heavy Oil

“…This method has a universal stimulating effect, helping to clean up heavy oil wells by reducing the viscosity of the oil, and also reducing the hydrostatic pressure in the oil column due to the release of nitrogen gas. Thus, both actions are aimed at ennobling the bottomhole formation zone by improving filtration characteristics as well as removing asphaltene-resin and paraffin deposits from the walls of the well and the wellbore equipment [16].…”

A new type of experimentally proposed in situ heat/gas clean foam fracturing fluid system

“…This system reduces the cold damage through the addition of heat-generating agents to the fracturing fluid to increase the temperature of the system (Tiwari et al 2014;Collesi et al 1987;McSpadden et al 1986;Ashton et al 1989). After the in situ heat fracturing fluid system is pumped into the formation, heat-generating agents can react to produce large amounts of heat and inert gas (Rollins and Taylor 1959;Al-Taq et al, 2014). The system forms a foam-like fracturing fluid, which effectively reduces fluid loss, increases pressure, and promotes flowback (Saidu Mohamed 2013;Mitchell et al 1984;Khalil and de Franco 1990).…”