Degradable Polyester Diverting Agents for Low-Temperature Oil Wells
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Solution Overview
Problem
Current diverting agents used in hydraulic fracturing, such as polylactic acid (PLA), do not degrade rapidly enough at low temperatures, necessitating the use of degradation enhancers that can damage well formations.
Innovation Solution
The use of particulate, degradable polyester diverting agents like ethylene glycol succinates, acid-terminated polyglycolic acids, and mixtures with half acid esters, which can degrade effectively at temperatures below 150°F without the need for degradation enhancers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polylactic acid (PLA) is used as a diverting agent in low-temperature wells, then the diverting agent can be used in the formation, but it does not degrade rapidly enough at temperatures below 130°F
Solution Approach 1:
The patent modifies the chemical structure of the polyester diverting agent by incorporating specific ester linkages and functional groups that are more susceptible to hydrolysis at low temperatures. This changes the degradation parameters of the material to enable rapid breakdown below 130°F without requiring external degradation enhancers
Solution Approach 2:
The patent uses composite polyester formulations combining multiple polymer components with complementary degradation characteristics. This composite approach creates a diverting agent that maintains structural integrity at well temperatures while degrading rapidly through multiple simultaneous pathways, solving the low-temperature degradation problem
2Productivity
If mineral acids or degradation enhancers are used to accelerate decomposition of the diverting agent, then the degradation speed increases, but the well formations are permanently damaged
Solution Approach 1:
The patent designs the polyester diverting agent to be self-degradable through inherent chemical structures that automatically hydrolyze at low temperatures. The material serves its own degradation needs without requiring external acids or enhancers, eliminating formation damage while maintaining rapid degradation speeds
Solution Approach 2:
The patent converts the typically harmful effect of water (which causes slow hydrolysis at low temperatures) into a beneficial degradation mechanism. By designing ester linkages that are highly susceptible to water attack at low temperatures, the naturally present formation water becomes the degradation agent, eliminating the need for harmful chemical enhancers
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
These diverting agents demonstrate improved degradability at low temperatures, enhancing the productivity of low-temperature wells by allowing for faster oil extraction without damaging well formations.
Implementation Method 1
The diverting agent must then leave the fractures, typically by decomposing or dissolving
Implementation Method 2
The diverting agent has a melting point greater than the average temperature within the formation
Data Source
AI summary
A hydraulic fracturing method for recovering oil from a low-temperature subterranean oil formation is disclosed. Before, during, or after inducing hydraulic fracturing within the formation, a particulate, degradable polyester diverting agent is introduced into the formation in an amount effective to improve oil production from the formation. The diverting agent is allowed to degrade, and oil is recovered. The diverting agent has a melting point greater than the average temperature of the formation and is selected from: (i) ethylene glycol succinates; (ii) acid-terminated ethylene glycol succinates; (iii) acid-terminated polyglycolic acids; (iv) acid-terminated polylactic acids; and (v) mixtures of any of (i) through (iv) with a half acid ester.