Well Placement Landing Map Using Closure Stress Calibration
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Solution Overview
Problem
Current methods for selecting profitable completion zones in hydrocarbon and mineral reservoirs rely on seismic survey data with limited vertical resolution and relative rock property representation, requiring substantial interpretation and incurring high drilling costs.
Innovation Solution
A computer-based well placement system that integrates seismic survey data with microfracture testing and sonic logs to create a landing map highlighting desirable completion zones by deriving a relationship between seismic-based closure stress and minimum in-situ stress, allowing for precise well placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If seismic survey data is used for well placement, then broad subsurface coverage is achieved, but vertical resolution and measurement precision are limited
Solution Approach 1:
The patent combines seismic survey data with borehole log data (microfracture testing and sonic logs) to create an integrated landing map. This merging allows the broad areal coverage of seismic data to be complemented by the high vertical resolution of borehole measurements, resolving the contradiction between coverage area and measurement precision.
Solution Approach 2:
The patent introduces an intermediary relationship between seismic-based CSS and borehole-based CSS through calibration using microfracture testing data. This intermediary calibration process allows seismic data to be transformed into accurate closure stress measurements, bridging the gap between broad coverage and precise measurement.
2Loss of information
If traditional seismic interpretation methods are used, then substantial interpretation effort is required, but reliability of completion zone selection is reduced
Solution Approach 1:
The patent implements a feedback mechanism where borehole measurement data (microfracture testing) is used to calibrate and validate the seismic-based CSS model. This feedback loop continuously improves the reliability of completion zone identification while reducing the need for extensive subjective interpretation.
Solution Approach 2:
The patent replaces the mechanical/subjective interpretation process with an automated computational system that uses calibrated CSS relationships. This substitution eliminates the need for substantial manual interpretation while significantly improving the objective reliability of completion zone selection.
3Measurement precision
If microfracture testing is performed to obtain direct closure stress measurements, then measurement precision is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The patent applies partial action by performing microfracture testing at selected borehole locations rather than continuously across the entire subsurface area. This partial sampling provides sufficient calibration data to establish CSS relationships without requiring excessive testing that would increase complexity and cost unnecessarily.
Data Source
AI summary
Desirable completion zones can be identified using closure stress in combination with one or more other attributes such as porosity. One computer-based well placement method includes using the computer to: process a seismic data volume to map the spatial distribution of a seismic-based CSS attribute; acquire logs from one or more boreholes in the subsurface region; derive from the logs a relationship between CSS and a minimum in-situ stress; apply the relationship to the CSS attribute map to produce a landing map that highlights desirable completion zones; and place one or more wells in the desirable completion zones. The borehole logs may include direct measurements of minimum in-situ stress (acquired via microfracture testing), sonic tool measurements of P-wave and S-wave velocity, and density tool measurements of bulk formation density.