Viscoelastic Surfactant Drill-in Fluid Pseudo-Filter Cake
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Solution Overview
Problem
Conventional drill-in fluids using polymers for subterranean reservoirs often cause formation damage when the filter cake is removed, leading to reduced permeability and compromised hydrocarbon flow.
Innovation Solution
A drill-in fluid comprising viscoelastic surfactants, internal breakers, viscosity enhancers, and fluid loss control agents forms a temporary pseudo-filter cake that can be easily broken and removed without damaging the formation, using degradable barriers and hydraulic pressure to control fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If polymer-based gelled fluids are used to form filter cakes, then fluid loss control is improved, but formation damage occurs and permeability is reduced when the filter cake is removed
Solution Approach 1:
The patent changes the chemical composition parameters of the drill-in fluid by replacing polymer-based gelling agents with viscoelastic surfactants. This parameter change allows the fluid to maintain gel structure for fluid loss control while enabling easy breakdown and removal without formation damage, thus resolving the contradiction between fluid loss control and formation protection
Solution Approach 2:
The patent employs a disposable degradable barrier material that is intentionally designed to be temporary and easily removable. This barrier provides temporary protection during drilling operations and then degrades completely, leaving no harmful residues in the formation, thus resolving the contradiction between providing protective function and avoiding formation damage
2Ease of operation
If temporary seals or plugs are used to block flow pathways, then fluid flow control is improved, but removal of the seal or plug may cause formation damage
Solution Approach 1:
The patent incorporates internal breakers within the drill-in fluid formulation that are prepared in advance to automatically trigger gel breakdown under specific downhole conditions (such as temperature or pH changes). This preliminary action ensures the gel breaks down at the right time without requiring external intervention, thus resolving the contradiction between maintaining temporary seal and enabling easy removal
Solution Approach 2:
The patent designs the drill-in fluid system to be self-breaking through the inclusion of internal breakers that automatically activate under downhole conditions. The system serves itself by breaking down the gel structure without requiring external breakers or additional operational steps, thus resolving the contradiction between providing temporary flow control and enabling easy removal without formation damage
3Ease of operation
If degradable barriers are used in flow conduits, then fluid flow control is improved, but the barriers require removal mechanisms
Solution Approach 1:
The degradable barrier is designed to automatically degrade and remove itself through chemical breakdown triggered by downhole conditions such as temperature, pH, or contact with formation fluids. This self-service mechanism eliminates the need for complex external removal systems, thus resolving the contradiction between providing flow control function and avoiding device complexity
Solution Approach 2:
The patent replaces mechanical removal systems with chemical degradation mechanisms. Instead of requiring mechanical retrieval or complex removal equipment, the barrier material chemically breaks down into soluble or dispersible products, thus resolving the contradiction between providing temporary flow control and avoiding device complexity
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 minimizes formation damage, allows for efficient hydrocarbon flow, and reduces the need for external breakers, enabling quick and complete clean-up of the drill-in fluid without relying on reservoir hydrocarbons.
Implementation Method 1
at least one viscoelastic surfactant (VES) in an amount effective to increase the viscosity of the water
Implementation Method 2
The degradable barrier is removed from the flow conduit, in one non-limiting embodiment by a fluid such as an acid, solvent and/or by temperature or time
Implementation Method 3
Hydraulic pressure of a fluid, such as or similar to the drill-in fluid previous described, is supplied within the interior space of the pipe and the flow conduit and forms a temporary barrier
Implementation Method 4
The temporary coating on the well bore wall adjacent the flow conduit is removed, such as by reducing the viscosity of the drill-in fluid
Data Source
AI summary
A flow conduit having at least one orifice is placed in the vicinity of a flow source, which in one non-limiting embodiment may be a hydrocarbon reservoir. The flow pathway between the orifice and the source is temporarily blocked with a degradable barrier. Once the flow pathway is physically placed, the degradable barrier is removed under the influence of an acid, a solvent, time and/or temperature. The flow source and the flow pathways are at least partially covered (and flow blocked by) a temporary coating such as a pseudo-filter cake formed by a viscoelastic surfactant-gelled aqueous drill-in fluid, and the flow conduit is extended to the flow source. The pseudo-filter cake is removed when viscosity is reduced by an internal breaker, and flow is then allowed. The method is useful in one context of recovering hydrocarbons where the flow conduit is a telescoping sleeve or tube that contacts the borehole wall.