In Situ Acid Generation for Filtercake Removal
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Solution Overview
Problem
Conventional methods for removing filtercakes from boreholes using aqueous acid solutions are hazardous and inefficient, often leaving behind untouched filtercake due to rapid reaction and fluid loss.
Innovation Solution
Generating acid in situ through the reaction of a nucleophilic organic molecule and an electrophile, which can produce strong acids that effectively break down acid-soluble components in the filtercake without relying on water, allowing for efficient filtercake removal in subterranean applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an aqueous acid solution is used to remove filtercake, then the filtercake can be contacted with acid for removal, but the acid reacts rapidly at the initial point of contact creating a fluid loss zone and leaving much of the filtercake untouched
Solution Approach 1:
The acid clean-up process is segmented into two distinct stages: (1) initial rapid reaction stage where acid reacts with the filtercake at the point of contact, and (2) subsequent slow reaction stage where the acid continues to react with remaining filtercake. This segmentation allows optimization of each stage - the rapid initial reaction creates a conductive pathway while the slow subsequent reaction ensures complete filtercake removal along the entire borehole surface.
Solution Approach 2:
The acid solution is preliminarily treated by adding a clay stabilizer before being pumped into the borehole. This preliminary action prevents the acid from reacting with formation clay minerals, which would otherwise create additional fluid loss zones and reduce the acid available for filtercake removal. The stabilizer is consumed in this preliminary protection phase, allowing the acid to then effectively remove the filtercake without further formation damage.
2Productivity
If an aqueous acid solution is used to remove filtercake, then the filtercake can be contacted with acid for removal, but tubular goods and equipment are corroded and personnel are hazardous
Solution Approach 1:
The concentration of free acid in the solution is carefully controlled and maintained at low levels (0-5% HCl equivalent) through the use of buffered acid systems. This parameter change reduces the corrosiveness of the solution to tubular goods and equipment while still providing sufficient acid to effectively remove the filtercake. The buffered system allows the acid to remain active for filtercake removal without becoming overly corrosive.
Solution Approach 2:
Clay stabilizers and other protective agents act as intermediaries between the acid solution and the formation/tubular goods. These substances are added to the acid solution and preferentially react with or protect against the acid, preventing direct contact between the acid and metal surfaces or formation minerals. The intermediaries are consumed in protecting the system, allowing the acid to safely perform its filtercake removal function.
3Productivity
If aqueous acid solution is used for filtercake removal, then the filtercake can be removed from borehole surfaces, but the method is not suitable for water-sensitive formations
Solution Approach 1:
The water content of the acid solution is reduced to below 50% (preferably below 20%) by using non-aqueous carriers such as oils, alcohols, or other organic solvents. This parameter change makes the solution compatible with water-sensitive formations by minimizing water influx that could damage the formation. Despite the reduced water content, the solution maintains sufficient acid concentration to effectively remove the filtercake from the borehole surface.
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
This method enables effective removal of filtercakes from borehole surfaces, reducing the risk of corrosion and fluid loss, and can be used in both aqueous and non-aqueous drilling fluids, as well as in water-sensitive formations, improving the efficiency of subterranean operations.
Implementation Method 1
the acid can be generated through the reaction of a nucleophilic organic molecule and an electrophile
Data Source
AI summary
A variety of methods, systems, and compositions are disclosed, including, in one embodiment, a method of servicing a borehole including providing a borehole servicing fluid in a borehole penetrating a subterranean formation, wherein the borehole servicing fluid includes a nucleophilic organic molecule and an electrophile. The method further may include reacting the nucleophilic organic molecule and the electrophile to generate at least an acidic species. The method further may include contacting an acid-soluble component in the subterranean formation with the acidic species such that the acidic species degrades the acid-soluble component.