Degradable Polymetaphosphate Bridging Agent for Drill-in Fluids
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Solution Overview
Problem
Current subterranean formation treatment fluids face challenges in depositing a high-strength filter cake that can be easily removed without chemicals, which is essential for maintaining wellbore permeability and reducing production downtime.
Innovation Solution
A drill-in fluid composition comprising an aqueous base fluid, a viscosifier, a fluid loss control additive, and a degradable high-strength polymetaphosphate bridging agent, which forms a filter cake that can be irreversibly degraded using an aqueous or acidic fluid, reducing fluid loss and facilitating efficient removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high strength polymetaphosphate material is used as bridging agent, then filter cake strength is improved, but filter cake removal difficulty increases
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the bridging agent. Specifically, it uses polymetaphosphate materials with controlled chain lengths and cross-linking densities that provide high strength when deposited but become susceptible to degradation under specific downhole conditions (temperature, pressure, chemical environment), enabling easy removal after serving their function.
Solution Approach 2:
The patent implements dynamics by creating a filter cake with time-dependent and condition-dependent properties. The polymetaphosphate bridging agent forms a strong, stable filter cake initially to control fluid loss, but under downhole conditions over time, the material degrades and becomes removable. This dynamic transformation allows the same material to provide both high strength during treatment and easy removal afterward.
2Ease of manufacture
If degradable polymetaphosphate material is used, then filter cake removal is facilitated, but filter cake strength is reduced
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the molecular parameters of the polymetaphosphate material, including chain length, degree of polymerization, and cross-linking density. These parameter optimizations enable the material to exhibit high strength characteristics during filter cake formation while maintaining degradability under specific downhole conditions, thus achieving both strong filter cake and easy removal.
3Ease of manufacture
If calcium carbonate particulate is used as bridging agent, then filter cake removal is easy, but filter cake strength is limited
Solution Approach 1:
The patent employs composite materials by combining polymetaphosphate bridging agents with complementary properties. The polymetaphosphate material integrates the advantages of both calcium carbonate (easy removal) and high-strength particulates (superior filter cake strength), creating a composite bridging agent that achieves both high strength and easy removability through its unique molecular structure and degradation characteristics.
4Reliability
If starch coated polymetaphosphate particulate is used, then diversion performance is improved, but filter cake removal difficulty increases at temperatures below 170°F
Solution Approach 1:
The patent applies parameter changes by optimizing the coating parameters and molecular structure of the polymetaphosphate material. Instead of using starch coating, the patent employs polymetaphosphate materials with controlled hydrophilicity, molecular weight, and chain structure that provide effective diversion performance while maintaining degradability at lower temperatures, thus enabling easy filter cake removal without requiring high temperatures or aggressive chemicals.
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 reduces fluid loss during treatments and allows for quick removal of the filter cake, minimizing downtime and preserving wellbore permeability without the need for chemical cleaners.
Implementation Method 1
a degradable high strength polymetaphosphate bridging agent, which forms a filter cake that can be irreversibly degraded using an aqueous or acidic fluid
Data Source
AI summary
Drill-in fluids disclosed herein comprise an aqueous base fluid, a viscosifier, a fluid loss control additive, and a degradable bridging agent comprising a degradable high strength polymetaphosphate material capable of undergoing an irreversible degradation downhole. The present disclosure further relates to a method for controlling fluid loss through a subterranean surface by using the drill-in fluid for form a filter cake on the subterranean surface. Also provided is a method of degrading a filter cake with an aqueous fluid or aqueous acidic fluid, wherein the filter cake is produced from the drill-in fluid. Further provided is a specific order of addition of constituents of the drill-in fluid, which results in improved filter cake performance and/or filter cake removal.