Noncompressible Lightweight Drilling Fluid for Managed Pressure Control
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Solution Overview
Problem
Current drilling fluids, especially those based on water or oil, face challenges in achieving low densities necessary for efficient hydrocarbon recovery without using compressible gases, which complicate equipment requirements, safety, and environmental concerns, and often cause wellbore damage due to high buoyancy and pressure.
Innovation Solution
A noncompressible, lightweight drilling fluid is developed using a hydrocarbon base liquid and styrenic butadiene diblock copolymer, with glass bubbles added to achieve densities of 8 pounds per gallon or less, allowing for controlled pressure and rheology management through recirculation and additive adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If compressed gas is used to lighten the drilling fluid column, then the hydrostatic pressure is reduced, but the equipment complexity and safety risks increase due to the need for compressors and gas handling systems
Solution Approach 1:
The invention extracts and eliminates the gas component from the drilling fluid system entirely. Instead of using aerated or nitrified fluids that require compressors and gas handling equipment, the patent employs a deaerated, non-aqueous drilling fluid that achieves the required light weight through chemical composition alone, thereby removing the need for complex gas compression and injection equipment
Solution Approach 2:
The invention changes the fundamental parameters of the drilling fluid by using a non-aqueous base fluid with specific gravity less than water and maintaining zero gas content. This parameter change allows the fluid to achieve the desired light weight effect without requiring gas compression equipment, resolving the contradiction between pressure reduction and equipment complexity
2Quantity of substance
If aerated or nitrified fluids are used to achieve low density, then the drilling fluid weight is reduced, but the rheology control and prediction become more difficult
Solution Approach 1:
The invention changes the fundamental composition parameters by using a deaerated non-aqueous drilling fluid with specific gravity less than water. This eliminates gas bubbles from the fluid system, allowing rheology to be measured and predicted using conventional equipment and methods at ambient conditions, thereby resolving the contradiction between achieving low density and maintaining measurable rheology
Solution Approach 2:
The invention replaces the complex, variable rheology of aerated fluids with a simple, stable non-aqueous fluid composition. This allows for easy and accurate rheology measurement using conventional, inexpensive equipment rather than requiring complex pressurized rheometers, resolving the measurement difficulty
3Stress or pressure
If gas is injected into drilling fluid to reduce density, then the hydrostatic column is lightened, but the fluid properties become unpredictable and harder to control
Solution Approach 1:
The invention extracts and removes all gas components from the drilling fluid system, using only deaerated liquid phases. This eliminates the compressibility and volume variability associated with gas, resulting in a fluid with stable, predictable composition and properties that can be precisely controlled throughout the drilling operation
Solution Approach 2:
The invention changes the fluid composition to use a non-aqueous base with specific gravity less than water and maintains zero gas content. This parameter change creates a fluid with stable, predictable properties that respond immediately to pressure control inputs, resolving the contradiction between pressure reduction and property stability
4Ease of operation
If conventional water-based or oil-based drilling fluids are used, then the drilling fluid provides good lubrication and cuttings transport, but the density is too high causing wellbore damage and lost circulation
Solution Approach 1:
The invention uses a composite non-aqueous drilling fluid composition consisting of a base fluid with specific gravity less than water, viscosity modifiers, and other functional additives. This composite formulation achieves the dual goal of low density to prevent wellbore damage while maintaining adequate viscosity and rheology for effective cuttings transport and wellbore lubrication
Solution Approach 2:
The invention changes the fundamental density parameter by using a non-aqueous base fluid with specific gravity less than water, while adjusting viscosity and other rheological parameters through additives. This allows the fluid to achieve low density for wellbore protection while maintaining operational effectiveness for drilling
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
This solution eliminates the need for compressors and gas separators, enables rapid pressure control, reduces equipment complexity and environmental impact, and maintains effective drilling performance with lower buoyancy, enhancing drilling efficiency and safety.
Implementation Method 1
The fluid, including a very light weight hydrocarbon base liquid, a styrenic butadiene diblock copolymer and an organoclay, is heated to achieve excellent rheology including thixotropicity
Implementation Method 2
Densities as low as 4 pounds per gallon are achieved with the addition of glass bubbles
Implementation Method 3
The fluid, including a very light weight hydrocarbon base liquid, a styrenic butadiene diblock copolymer and an organoclay, is heated to achieve excellent rheology
Data Source
AI summary
A very light weight, noncompressible drilling fluid including a very light weight hydrocarbon base liquid, and a styrenic butadiene diblock copolymer is heated to achieve excellent rheology including thixotropicity, making an effective drilling fluid with a density of 8 pounds per gallon or less. Densities as low as 4 pounds per gallon are achieved with the addition of glass bubbles. The glass bubbles may, but normally will not, exceed 50% by volume. A method of making the drilling fluid includes passing the light weight liquid and the copolymer through a cavitation device. The invention includes drilling and with and recirculating the fluid to maintain the desired density, viscosity and rheology by adjusting the ingredients accordingly. A method of managed pressure drilling employs the novel fluid, enabling control of drill pressure and physical properties of the fluid including equivalent circulating density.