Thermochemical Well Cleanup Composition for Barite Filter Cake Removal
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Solution Overview
Problem
Current well cleanup methods, particularly for horizontal wells, face challenges in efficiently removing barite filter cakes due to uncontrolled reactions and incompatibilities of formulation ingredients, leading to incomplete removal and potential formation damage.
Innovation Solution
Aqueous compositions containing ammonium and nitrite salts in specific molar ratios, combined with ethylenediamine tetraacetic acid (EDTA), are introduced into the wellbore to initiate exothermic chemical reactions, generating heat and pressure that disrupt barite filter cakes, allowing for efficient removal without complex equipment or foaming agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional acid-based methods are used to remove barite filter cakes, then removal efficiency is improved, but corrosion and stability issues worsen
Solution Approach 1:
The patent changes the chemical parameters by replacing traditional acid-based formulations with a composition containing ammonium nitrite salt and EDTA at specific concentrations and molar ratios. This parameter change maintains removal efficiency while eliminating corrosion problems associated with acids
Solution Approach 2:
The patent converts the previously harmful exothermic reaction of ammonium nitrite into a beneficial tool by controlling the reaction to generate heat and pressure that actively disrupts and removes the filter cake, transforming a potentially unstable reaction into a useful cleaning mechanism
2Productivity
If exothermic chemical reactions are used to generate heat and pressure, then filter cake disruption efficiency is improved, but reaction control difficulty worsens
Solution Approach 1:
The patent controls the exothermic reaction by precisely specifying the molar ratio (1:1) and concentration ranges of ammonium nitrite salt and EDTA, transforming an uncontrollable reaction into a reliable process through parameter optimization
Solution Approach 2:
The patent uses EDTA as an intermediary substance that not only chelates barium ions but also moderates the exothermic reaction of ammonium nitrite, providing dual functionality that enhances both effectiveness and controllability
3Productivity
If complex formulation ingredients are used, then removal effectiveness is improved, but formulation incompatibility worsens
Solution Approach 1:
The patent extracts and eliminates incompatible ingredients from complex formulations, retaining only the essential components (ammonium nitrite salt and EDTA) that provide the necessary cleaning action while ensuring chemical compatibility and stability
Solution Approach 2:
The patent creates a composite chemical system where ammonium nitrite salt and EDTA work synergistically, combining the exothermic reaction capability with chelating action to achieve effective filter cake removal while maintaining formulation stability
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 achieves at least 85% removal of filter cake mass within 6 hours, with up to 95% efficiency, while avoiding corrosion and stability issues associated with traditional acid-based methods, and is effective for both water-based and oil-based drilling fluids.
Implementation Method 1
allowing the aqueous composition to reach a temperature in the wellbore sufficient to initiate an exothermic chemical reaction of the components of the aqueous composition and thereby cause a temperature and/or pressure surge at the wellbore face to disrupt the filter cake
Implementation Method 2
Aqueous compositions containing ammonium and nitrite salts in specific molar ratios, combined with ethylenediamine tetraacetic acid (EDTA), are introduced into the wellbore to initiate exothermic chemical reactions, generating heat and pressure that disrupt barite filter cakes
Data Source
AI summary
A well cleanup process involves removing an impermeable filter cake from a formation face with thermochemical and chelating agents to allow formation fluids to flow from a reservoir to a wellbore. The method may be used with oil and water-based drilling fluids with varied weighting agents, e.g., bentonite, calcium carbonate, or barite. Such thermochemical agents may involve two salts, e.g., NO2− and NH4+, which, when mixed together, can generate pressure and heat, in addition to hot H2O and/or N2. For example, the thermochemical agents may comprise Na+, K+, Li+, Cs+, Mg2+, Ca2+, and/or Ba2+ with NO2− and NH4+ with F−, Cl−, Br−, I−, CO32−, NO3−, ClO4−, and/or −OH. The thermochemical agents in combination with a chelator such as EDTA can removed the filter cake after 6 hours with a removal efficiency of 89 wt % for the barite filter cake in water based drilling fluid, exploiting the generation of a pressure pulse and heat which may disturb the filter cake and/or enhance barite dissolution and polymer degradation.