Weighted Fluid Loss Control Pill for Wellbore Sealing
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Solution Overview
Problem
Current completion fluids used in hydrocarbon reservoirs are lost to the formation, reducing efficiency and increasing costs, as they are difficult to remove from perforations and fractures, leading to reduced hydrocarbon production and the need for costly remedial procedures.
Innovation Solution
A composition of weighted completion fluids comprising polymetaphosphate, a biopolymer suspension agent, and a fluid loss control additive that temporarily blocks openings in the formation, allowing for completion operations and can be quickly removed with an acidic fluid, preventing permanent blockage and maintaining reservoir permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gel or particulate fluid loss control agents are used to seal openings in the formation, then fluid loss is prevented, but the agents may form impenetrable plugs that cannot be removed, stopping hydrocarbon production
Solution Approach 1:
The patent applies parameter changes by using polymetaphosphate composition that changes its solubility parameter in response to pH changes. The composition is insoluble in neutral completion fluids (providing reliable sealing) but becomes soluble when exposed to acidic formation fluids (enabling easy removal). This dynamic parameter change resolves the contradiction between effective sealing and easy removal.
Solution Approach 2:
The patent employs a disposable sealing mechanism where the polymetaphosphate composition is designed to be temporary. It performs its sealing function during completion operations and then naturally dissolves in formation fluids, eliminating the need for complex removal procedures. This short-living approach resolves the contradiction by accepting that the sealing agents are meant to be transient rather than permanent.
2Reliability
If viscous completion fluids are used to suspend weighting materials, then wellbore control is achieved, but the fluids are lost into formations, reducing hydrocarbon production
Solution Approach 1:
The patent extracts the fluid loss control function from the main completion fluid system. Instead of relying on the viscosity of the entire completion fluid to prevent loss, it uses a separate polymetaphosphate composition that specifically targets and seals flow paths. This extraction allows the completion fluid to maintain wellbore control while the polymetaphosphate handles the fluid loss prevention, reducing overall fluid loss into the formation.
Solution Approach 2:
The patent applies local quality by concentrating the fluid loss control mechanism at specific flow paths rather than throughout the entire formation. The polymetaphosphate composition selectively seals perforations and fractures where fluid loss occurs, while leaving the rest of the formation permeable. This localized approach prevents fluid loss without compromising overall hydrocarbon production.
3Reliability
If soluble solid particulates are used to bridge openings, then fluid loss is blocked, but the particulates cannot be removed by circulated solvents, requiring costly reperforation
Solution Approach 1:
The patent uses parameter changes in the chemical environment (pH) to control the solubility of the sealing composition. The polymetaphosphate remains insoluble in the neutral pH environment of completion fluids (providing reliable blocking) but becomes soluble when exposed to the acidic pH of formation fluids (enabling easy removal by circulated solvents). This resolves the contradiction by making removability dependent on environmental conditions rather than inherent material properties.
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 solution effectively prevents fluid loss during completion operations, allowing for efficient hydrocarbon production by temporarily sealing openings and ensuring quick removal of the sealing agents, thus reducing the need for costly reperforation and maintaining reservoir permeability.
Implementation Method 1
the polymetaphosphate and fluid loss control additive temporarily block openings such as those in a wellbore communicating with a subterranean formation
Implementation Method 2
the polymetaphosphate and fluid loss control additive can be removed by dissolution after a few minutes of contact with an acidic fluid circulated through the wellbore
Implementation Method 3
a biopolymer suspension agent for increasing the viscosity of the weighted brine
Data Source
AI summary
Novel completion fluid compositions for fluid loss control during completion and workover operations conducted on a wellbore penetrating a subterranean formation are disclosed. In particular, the composition is a weighted brine fluid having a polymetaphosphate composition, a biopolymer suspension agent, and a fluid loss control additive. These novel compositions provide a means to temporarily seal a wellbore communicating with a subterranean formation to enable completion or workover operations to be performed, after which the composition can be removed by contact with an acidic composition.