Compressible Objects with Foam Interiors for Variable Density Drilling Mud
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Solution Overview
Problem
The existing methods for drilling operations face challenges in maintaining the optimal density of drilling mud within the pore pressure gradient (PPG) and fracture pressure gradient (FG) as depth increases, leading to inefficiencies and increased costs due to the need for multiple casing strings and large volumes of drilling mud, particularly in deep wells.
Innovation Solution
The use of compressible objects with a shell enclosing a partially foamed interior, which change volume in response to pressure changes, are integrated into the drilling fluid to create a variable density drilling mud, allowing for adjustments in mud weight between PPG and FG, thereby reducing the number of casing strings and optimizing drilling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the weight of the drilling mud is increased to maintain it above the pore pressure gradient (PPG) at greater depths, then the drilling mud can prevent kicks and allow drilling operations to continue, but the drilling mud may leak off into the formation if the weight exceeds the fracture pressure gradient (FG)
Solution Approach 1:
The patent applies dynamics by using compressible objects that change their volume in response to pressure changes. These objects are introduced into the drilling mud to create a variable density system where the effective mud weight can dynamically adjust with depth and pressure conditions, allowing the system to maintain reliability without excessive mud weight that would cause losses.
Solution Approach 2:
The patent changes the density parameter of the drilling mud by incorporating compressible objects. These objects alter the overall density characteristics of the mud system, enabling precise control of mud weight to stay within the safe operating window between PPG and FG, thereby preventing both kicks and mud loss into the formation.
2Reliability
If multiple casing strings are installed to maintain drilling mud weight within PPG and FG at different depth intervals, then drilling operations can proceed to greater depths, but the cost and time of drilling operations increase
Solution Approach 1:
The patent changes the density parameter of the drilling mud using compressible objects, allowing a single casing string to handle multiple depth intervals that would traditionally require multiple casing strings. This parameter change enables the drilling mud to maintain appropriate weight at various depths without requiring intermediate casing installations, reducing both time and cost.
Solution Approach 2:
The compressible objects serve multiple functions: they adjust mud weight dynamically, eliminate the need for multiple casing strings, and enable drilling through varying pressure gradients. This multi-functionality reduces the complexity and time associated with traditional multi-casing drilling operations.
3Ease of operation
If the diameter of the initial casing string is increased to provide sufficient wellbore diameter for tools at subsurface formations, then the wellbore can accommodate drilling tools, but the cost increases due to increased volume of cuttings, cement, and drilling mud
Solution Approach 1:
The patent changes the density parameter of the drilling mud to compensate for the reduced volume caused by smaller casing strings. By increasing the density of the mud (while keeping it within safe limits using compressible objects), the hydrostatic pressure is maintained despite the smaller wellbore volume, allowing smaller casing to be used without sacrificing tool accessibility or 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
This approach enables deeper drilling with reduced costs by maintaining the necessary mud weight, minimizing mud loss, and reducing the number of casing strings required, thus enhancing operational efficiency and economic feasibility.
Implementation Method 1
compressible objects having a shell that encloses an interior region, the interior region at least partially filled with foam... adapted to compress when external pressures exceed an internal pressure to reduce the volume of the compressible object
Data Source
AI summary
A compressible object is described that may be utilized in drilling mud and with a drilling system to manage the density of the drilling mud. The compressible object includes a shell that encloses an interior region. The interior region of the shell is at least partially filled with a foam. The internal pressure of the compressible object may be greater than about 200 psi (pounds per square inch) at atmospheric pressure, greater than 500 psi at atmospheric pressure, greater than 1500 psi at atmospheric pressure or more preferably greater than 2000 psi at atmospheric pressure.