PLA Filtration Control in Drilling Fluids With Easy Acid Cleanup
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Solution Overview
Problem
Existing drilling fluids rely on starch as a filtration control agent, which is inefficient to remove in harsh reservoir environments and can cause formation damage, leading to reduced well productivity.
Innovation Solution
Use of polylactic acid (PLA) particle dispersion as a filtration control agent that forms an impermeable filter cake, easily removable with mild acids even at low temperatures, compatible with high salinity brines and common drilling fluid components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If starch is used as filtration control agent, then filtration performance is improved, but removal efficiency deteriorates in harsh reservoir environments
Solution Approach 1:
The patent changes the chemical composition parameter from starch to polylactic acid (PLA) particles, which maintains filtration performance through similar filter cake formation mechanisms while improving removal efficiency through biodegradation and acid solubility, especially effective in harsh reservoir environments
Solution Approach 2:
The patent employs PLA particles that are designed to be temporary and easily removable after serving their filtration purpose, contrasting with starch that persists and causes formation damage, aligning with the principle of using disposable materials that fulfill their function and are then easily discarded
2Reliability
If starch is used as filtration control agent, then filtration performance is improved, but formation damage increases
Solution Approach 1:
The patent changes the material composition from starch to polylactic acid (PLA) particles, which maintain the necessary filtration performance while eliminating formation damage through biodegradation and acid solubility, allowing complete removal after drilling operations
Solution Approach 2:
The patent converts the potential harm of persistent filter cake materials into benefit by using PLA that naturally degrades and can be easily removed with mild acids, transforming what would be a harmful persistent residue into a beneficial easily-removable material
3Ease of operation
If enzymatic removal is used for starch filter cake, then removal capability is improved, but effectiveness deteriorates in harsh local environment
Solution Approach 1:
The patent employs PLA particles that are self-service in terms of removal, as they can be degraded by naturally occurring microorganisms in the reservoir environment or easily dissolved with mild acids, eliminating the need for specialized enzymatic treatments and their associated limitations
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
PLA dispersion forms a tough, impermeable filter cake that is easily cleaned up with mild acids, maintaining well integrity and preventing formation damage, suitable for a wide range of reservoir temperatures.
Implementation Method 1
The PLA dispersion and calcium carbonate form an impermeable PLA-filter cake to block pores and stop whole fluid invasion in the formation
Implementation Method 2
Removal of the filter cake is accomplished by injection of a mild organic acid like acetic acid that hydrolyzes the PLA under low temperature reservoir conditions
Data Source
AI summary
A well fluid containing submicron polylactic acid (PLA) particle dispersions for use as a filtration control agent have applicability in low temperature reservoirs and are easy to clean-up after treatment. Methods for the application of PLA containing drilling, completion or drill-in fluids are also discussed.