Horizontal Well Permeability Calculation Using Production Logs
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Solution Overview
Problem
Current methods for determining permeability in horizontal wells are inaccurate and limited, especially in heterogeneous reservoirs with faults, fractures, and high conductive flow channels, as they rely on indirect measurements and empirical models that perform poorly across different formations.
Innovation Solution
A downhole tool and computer system that calculates permeability using multiphase production logs, dividing the horizontal well into segments and applying the generic Darcy's law for multiphase flow to estimate permeability profiles on a foot-by-foot basis, incorporating fluid properties, relative permeability, and production data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If core plugs or formation fluid testers are used to directly determine permeability, then measurement precision is improved, but device complexity and operational difficulty increase due to limited core availability and discrete point measurements
Solution Approach 1:
The patent replaces mechanical core sampling and laboratory testing with a downhole tool that uses electrical measurements and production logging data to calculate permeability. The system substitutes physical core analysis with computational methods based on production data, relative permeability curves, and reservoir parameters, eliminating the need for actual core plugs while maintaining continuous along-wellbore permeability profiles.
Solution Approach 2:
The patent introduces an intermediary computational model that bridges production logging data and permeability calculation. The system uses relative permeability curves as intermediaries to translate production data into permeability profiles, and employs a downhole tool with computational algorithms to mediate between measurable parameters (production rates, pressures) and the target parameter (permeability).
2Ease of operation
If wireline-log responses are used to estimate permeability, then ease of operation is improved, but measurement precision deteriorates due to indirect measurements and empirical model limitations
Solution Approach 1:
The patent changes the fundamental parameters used for permeability estimation from indirect wireline-log correlations to direct production data measurements. Instead of using empirical correlations between porosity and permeability, the system uses actual production rates, pressures, and relative permeability curves to calculate permeability, fundamentally changing the approach from indirect estimation to direct calculation based on flow equations.
Solution Approach 2:
The patent segments the wellbore into multiple intervals along the horizontal well path, calculating permeability for each segment independently using production data specific to that segment. This segmentation allows the system to capture spatial variations in permeability and apply localized production data to each segment, improving both accuracy and operational flexibility.
3Ease of manufacture
If empirical models based on porosity and water saturation are used, then ease of manufacture is improved, but adaptability deteriorates when applied to different formations with faults, fractures, and high conductive flow channels
Solution Approach 1:
The patent introduces dynamic elements to the permeability calculation system by using actual production data that varies with time and conditions, rather than static empirical correlations. The system dynamically adjusts calculations based on measured production rates, pressures, and relative permeability curves specific to each formation, allowing adaptation to heterogeneous reservoirs with faults, fractures, and high conductive flow channels.
Solution Approach 2:
The patent applies local quality by calculating permeability profiles specific to each well segment based on local production data and formation characteristics. Instead of using a single empirical model for the entire formation, the system tailors permeability calculations to local conditions, using segment-specific production rates, pressures, and relative permeability curves to accurately represent heterogeneous reservoir properties.
4Productivity
If continuous permeability profiles are estimated for horizontal wells, then productivity is improved through better reservoir characterization, but loss of time increases due to the complexity of downhole tool operations and data processing
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing relative permeability curves and reservoir parameters before the actual permeability calculation is needed. The downhole tool uses pre-computed relative permeability data and reservoir properties to quickly calculate permeability profiles during production logging operations, reducing real-time computational time while maintaining accuracy.
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 method provides accurate permeability profiles for horizontal wells, improving inflow control device design, intelligent well completions, and overall oil recovery by accounting for complex reservoir characteristics and fluid flow dynamics.
Implementation Method 1
calculating, for each respective well segment, a horizontal permeability using the fluid properties, relative permeability to oil, relative permeability to water, a trajectory of the horizontal well, completion specifications of the horizontal well, and actual production logging data
Implementation Method 2
a downhole tool for permeability calculation... receive (i) fluid properties associated with the horizontal well, under downhole production logging conditions; (ii) relative permeability to oil and relative permeability to water
Data Source
AI summary
A downhole tool for permeability calculation includes a body configured for insertion into and retraction from a horizontal well, and coupled with a computer system that includes an interface operable to receive (i) fluid properties associated with the horizontal well, under downhole production logging conditions; (ii) relative permeability to oil and relative permeability to water, for the horizontal well; and (iii) actual production logging data associated with the horizontal well. The computer system may also include one or more processors that are operable to (i) determine an approximate upper boundary and an approximate lower boundary of the horizontal well; (ii) divide the horizontal well into a plurality of well segments; and (iii) calculate, for each respective well segment, a horizontal permeability.