Drilling Fluid Testing for Borehole Stability and Fracture Pressure
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Solution Overview
Problem
The challenge lies in determining the link between drilling fluid properties and formation strength to prevent unintentional formation breakdown during drilling and ensure hydraulic fracturing, as existing methods fail to accurately predict borehole stability and fracture pressure.
Innovation Solution
A method involving the selection and formulation of drilling muds based on rock mechanical properties, fluid invasion testing, and geomechanical modeling to determine a mud weight range that ensures formation stability and enables successful hydraulic fracturing, involving the analysis of drilling mud formulations, core characterization, and finite element modeling to predict optimal mud weights for drilling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If drilling mud weight is increased to prevent borehole instability, then borehole stability is improved, but formation breakdown pressure increases making hydraulic fracturing difficult
Solution Approach 1:
The patent applies parameter changes by systematically varying mud weight, filtration rate, and other drilling fluid properties to identify optimal ranges that simultaneously achieve borehole stability and controlled formation breakdown. The method determines specific mud weight ranges and filtration rate limits that prevent excessive formation strength increase, allowing hydraulic fracturing to occur at manageable pressures.
Solution Approach 2:
The patent implements preliminary action through pre-drilling laboratory tests on core plugs to characterize rock mechanical properties and determine formation breakdown pressure before actual drilling operations. This preliminary characterization allows prediction of optimal mud weight ranges that prevent borehole instability while enabling successful hydraulic fracturing, avoiding trial-and-error during field operations.
2Productivity
If drilling fluid filtration rate is increased to improve borehole cleaning, then borehole cleaning is improved, but formation damage increases due to excessive fluid invasion
Solution Approach 1:
The patent applies parameter changes by establishing specific filtration rate limits and controlling the composition of drilling fluids to optimize the balance between borehole cleaning and formation protection. The method determines maximum filtration rates that prevent excessive fluid invasion into the formation while maintaining adequate borehole cleaning efficiency, thereby reducing formation damage.
Solution Approach 2:
The patent uses core plugs as an intermediary medium to simulate formation conditions and test drilling fluid properties in the laboratory. By measuring fluid invasion and mechanical property changes in core plugs before actual drilling, the method identifies optimal drilling fluid formulations that clean the borehole effectively without causing excessive formation damage during actual operations.
3Stability of the object's composition
If drilling mud formulation is optimized for borehole stability, then borehole stability is improved, but prediction accuracy of formation breakdown pressure decreases
Solution Approach 1:
The patent implements preliminary action by conducting comprehensive laboratory tests on core plugs to characterize rock mechanical properties, permeability, and formation breakdown pressure before drilling operations. This preliminary data, combined with drilling mud formulation optimization, enables accurate prediction of formation breakdown pressure while maintaining borehole stability, resolving the contradiction between stability optimization and prediction accuracy.
Solution Approach 2:
The patent applies feedback by using laboratory test results from core plugs to validate and refine drilling mud formulation predictions. The method compares predicted formation breakdown pressure with actual measured values from core plug testing, adjusting the formulation optimization process to improve prediction accuracy while maintaining borehole 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 allows for the accurate prediction of mud weights required to prevent borehole instability and facilitate hydraulic fracturing, reducing the risk of formation damage and operational costs by quantifying the influence of drilling fluids on rock mechanical properties and formation breakdown pressure.
Implementation Method 1
performing a fluid invasion of the core plugs with drilling muds
Data Source
AI summary
Systems and methods for quantifying drilling fluid influence on formation mechanical properties are disclosed. The methods include obtaining drilling mud formulations and properties; determining a subset of the drilling mud formulations; obtaining core plugs from a subsurface; measuring first rock mechanical properties from the core plugs for each of the subset of the drilling mud formulations; performing a fluid invasion of the core plugs with drilling muds; measuring second rock mechanical properties of the core plugs after the fluid invasion; modeling an effect of the drilling muds on a formation breakdown; determining a mud weight range for each of the subset of the drilling mud formulations; and selecting a preferred drilling mud formulation for a drilling operation based on the mud weight range for the subset of the drilling mud formulations.