Gamma Density and Acoustic Standoff Estimation for Mud Weight
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Solution Overview
Problem
Accurate determination of mud weight during drilling operations is challenging due to variations in drilling fluid properties under downhole conditions, and existing methods often require expensive additional sensors or are inaccurate.
Innovation Solution
A system and method using gamma density and acoustic caliper measurements to determine standoff and mud density, employing iterative refinement processes to correct for errors without needing pressure, temperature, or rheology data, utilizing a spine-and-rib diagram for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors are deployed for mud weight calculations, then measurement precision may improve, but device complexity and cost increase
Solution Approach 1:
The patent combines gamma density measurements and acoustic caliper measurements into a unified system that calculates mud weight through integrated data processing. The controller merges density tool responses with acoustic echo time measurements to derive mud weight indirectly, eliminating the need for separate mud weight sensors while maintaining measurement accuracy through computational synthesis of multiple measurement modalities.
Solution Approach 2:
The patent introduces standoff and formation density as intermediary parameters that mediate between the primary measurements (density and acoustic responses) and the target parameter (mud weight). By calculating standoff approximation and formation density first, then using these intermediaries to solve for mud weight, the system achieves accurate mud weight determination without direct sensing, reducing device complexity while maintaining precision.
2Device complexity
If surface measurements are used for mud weight determination, then device complexity is reduced, but measurement precision deteriorates due to pressure and temperature variations
Solution Approach 1:
The patent performs preliminary calculations of standoff approximation and formation density using downhole measurements before computing mud weight. By establishing these intermediate parameters in-situ under downhole pressure and temperature conditions, the system compensates for environmental variations before deriving the final mud weight value, ensuring accuracy without requiring complex real-time correction systems.
Solution Approach 2:
The patent implements an iterative feedback process where the controller uses initial mud weight approximations to refine standoff calculations, then uses refined standoff values to recalculate formation density and mud weight. This feedback loop continuously improves measurement precision by using each calculation to enhance the accuracy of subsequent calculations, maintaining high precision with a relatively simple device configuration.
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
Provides accurate mud weight measurements that enhance drilling operations by improving standoff and mud density calculations, enabling better steering decisions and borehole stability without additional equipment costs.
Implementation Method 1
a gamma density tool, such as those manufactured by Services Industries, a division of Baker Hughes, Inc. of Houston, Tex.
Implementation Method 2
an acoustic module (e.g., an acoustic caliper), and a controller
Data Source
AI summary
A method for determining at least one of a mud density or a standoff, includes determining, a short-spaced density, a long-spaced density, and a time of sound propagation between a tool body and a borehole wall. The method also includes determining, based at least in part on the short-spaced density and the long-spaced density, a formation density using a spine-and-rib-diagram. The method further includes determining a distance-to-spine value based on the short-spaced density, the long-spaced density, and the formation density. The method includes determining a mud density approximation, based at least on the distance-to-spine value. The method also includes determining a standoff approximation, based at least on the mud density approximation. The method further includes determining, based at least on the mud density approximation and the standoff approximation, at least one of a computed mud density or a computed standoff.