Cement-Forming Drilling Fluid for Lost Circulation Control
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Solution Overview
Problem
Current drilling fluids face challenges in preventing fluid loss into subterranean formations, particularly in naturally fractured zones, due to insufficient operational robustness and premature gelation, which can cause damage to the near-wellbore region and hinder effective drilling and well completion.
Innovation Solution
A cement-forming aqueous fluid with viscoelastic surfactants, monovalent or multivalent salts, magnesium powder, and a retarder is introduced, which forms pseudo-crosslinked micelles to increase viscosity and inhibit fluid loss, allowing for controlled gelation and cement formation at the wellbore temperature, preventing fluid leakage into the formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If large amounts of weighting agents are used to increase fluid density, then the fluid density increases, but the dispersibility of other fluid components deteriorates
Solution Approach 1:
A dispersant is introduced as an intermediary substance to facilitate the uniform distribution of weighting agents and other components in the drilling fluid. The dispersant acts as a mediator that prevents aggregation of barite particles and maintains fluid component dispersibility even at high densities (14-20 ppg), resolving the contradiction between achieving high fluid density and maintaining component dispersibility.
2Reliability
If polymer resin sealing is used to prevent fluid loss, then fluid loss control improves, but premature gelation occurs
Solution Approach 1:
The patent changes the chemical parameters of the sealing mechanism by replacing polymer resin crosslinking with magnesium powder-cement-based sealing. This parameter change eliminates premature gelation while maintaining fluid loss control, as the cement-based system allows for controlled setting time adjustment through water-to-cement ratio and chemical additives, preventing unwanted early gelation that occurs with polymer resins.
3Reliability
If thixotropic slurry is used for lost circulation prevention, then fluid loss control improves, but operational robustness deteriorates
Solution Approach 1:
The patent employs a composite material system combining magnesium powder, cement, and VES (viscoelastic surfactant) to create a lost circulation prevention fluid with superior operational robustness. This composite approach integrates the benefits of thixotropic behavior for fluid loss control while adding the operational advantages of cement-based materials, including predictable setting characteristics, high strength development, and resistance to premature gelation, thereby resolving the contradiction between fluid loss control and operational robustness.
4Reliability
If high density fluid is used to balance formation pressure, then wellbore stability improves, but fluid loss into formation increases
Solution Approach 1:
The patent applies local quality by creating a specialized high-density fluid composition with enhanced filtration control properties specifically tailored for use in fractured formations. The fluid incorporates magnesium powder and cement components that locally seal off fracture pathways while maintaining the high density needed for wellbore stability, thus preventing fluid loss into the formation at critical locations without sacrificing overall wellbore stability.
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 provides a robust and pumpable fluid with high viscosity that effectively prevents fluid loss into the formation, maintaining operational efficiency and allowing for post-job acid flush cleanup, reducing damage to the reservoir and enhancing drilling and completion processes.
Implementation Method 1
increasing the viscosity of the cement-forming aqueous fluid by the action of the at least one VES forming elongated micelles
Implementation Method 2
the at least one monovalent salt is present in an amount effective to pseudo-crosslink the elongated VES micelles to further increase the viscosity of the aqueous fluid
Implementation Method 3
forming a cement by reacting at least one magnesium powder and the water
Implementation Method 4
The aqueous fluid includes... a dispersant
Data Source
AI summary
A formulation for use as a lost circulation preventive material is a cement-forming aqueous fluid comprising water, a viscoelastic surfactant (VES), a monovalent or multivalent salt, a magnesium powder, a retarder, a weighting material, and a dispersant. The formulation is used in a method of drilling into a subterranean formation that includes introducing into a wellbore passing at least partially through the subterranean formation the cement-forming aqueous fluid, and further increasing the viscosity of the aqueous fluid with the VES; where the monovalent salt is present in an amount effective to pseudo-crosslink the elongated VES micelles to further increase the viscosity of fluid. The formulation further forms a cement by reacting the magnesium powder and the water which reaction is retarded by the retarder. The water may be saline water. When the fluid density is greater than 14 pounds per gallon, a dispersant is required, such as a sulfonated copolymer.