Endothermic Solid Particles for Acid Penetration in Carbonate Formations
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Solution Overview
Problem
The rapid reaction of acidic fluids with carbonate subterranean formations at elevated depths limits the radial penetration of acid and results in hydrocarbon production constraints, as the acid dissipates quickly, forming channels near the wellbore rather than deep within the formation.
Innovation Solution
The use of well treatment fluids containing solid particles such as urea, ammonium nitrate, and barium hydroxide, encapsulated or in emulsion form, which initiate an endothermic reaction upon deployment, cooling the formation and reducing the acid-rock reaction rate, allowing for deeper acid penetration and enhanced hydrocarbon extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acidic fluids are injected into deep carbonate formations, then hydrocarbon extraction is enhanced, but the acid reacts rapidly with the rock matrix before achieving deep penetration
Solution Approach 1:
The patent changes the temperature parameter of the formation by introducing endothermic reactions that absorb heat and lower the formation temperature. This parameter change reduces the reaction rate between acid and carbonate rock, allowing acid to penetrate deeper into the formation before being consumed, thereby resolving the contradiction between deep penetration and rapid reaction.
Solution Approach 2:
The patent introduces endothermic reaction materials as intermediaries that absorb excess heat from the acid-carbonate reaction. These intermediaries act as mediators by consuming thermal energy and preventing it from accelerating the unwanted side reaction, thus enabling deeper acid penetration while maintaining hydrocarbon extraction effectiveness.
2Length of moving object
If large volumes of acid are used to achieve deep penetration, then radial penetration is improved, but the acid is spent only on rock mass around the wellbore and loses dissolving capacity
Solution Approach 1:
By changing the temperature parameter through endothermic reactions, the patent reduces the reaction rate constant of the acid-carbonate system. This allows the same volume of acid to penetrate deeper into the formation without being rapidly consumed, thereby improving penetration depth while reducing acid volume consumption.
Solution Approach 2:
The patent converts the harmful effect of rapid acid consumption near the wellbore into a beneficial cooling effect. The endothermic reactions that initially seem to compete with acid dissolution actually serve to lower the formation temperature and reduce the overall reaction rate, allowing acid to travel farther before being spent.
3Speed
If elevated temperatures increase acid reactivity with carbonate, then reaction rate is improved, but channels form near the wellbore instead of deep flow channels
Solution Approach 1:
The patent directly addresses this contradiction by changing the temperature parameter from elevated to reduced levels through endothermic reactions. This parameter change simultaneously reduces both the reaction rate and the tendency to form shallow channels, allowing for the creation of deep flow channels while maintaining controlled reaction rates.
Solution Approach 2:
The patent applies preliminary anti-action by introducing endothermic materials that preemptively absorb heat before the acid can rapidly react with the carbonate rock. This preliminary cooling action prevents the formation of shallow channels by counteracting the temperature-driven acceleration of the reaction before it can occur.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces the acid-rock reaction rate, enabling deeper penetration of the acid and forming conductive flow channels that connect the hydrocarbon-bearing formation to the wellbore, thereby increasing hydrocarbon production.
Implementation Method 1
releasing the solid particles from the capsules or emulsion within the formation, initiating an endothermic reaction and cooling the formation
Data Source
AI summary
Well treatment fluids may include solid particles comprising one or more components selected from the group consisting of urea, ammonium nitrate, ammonium chloride, barium hydroxide, and ammonium thiocyanate. These well treatment fluids may also include a carrier fluid, which may be an aqueous polymeric fluid, an oil, or combinations thereof. The aqueous polymeric fluid may include a polymer selected from the group consisting of guar gum, hydroxypropyl guar, carboxymethyl hydroxypropyl guar, cellulose, or polyacrylamide. The oil may include a material selected from the group consisting of diesel, mineral oil, and wax. Methods for reducing an acid carbonate reaction in a carbonate formation may include pumping a composition of solid particles into a formation; releasing the solid particles from the capsules or emulsion within the formation; and injecting an acid following the releasing step or during pumping, wherein the acid carbonate reaction is carried out at a reduced reaction rate.