Stoneley Wave Logging for Cased Hole Perforation Evaluation
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Solution Overview
Problem
Conventional methods are inadequate for accurately evaluating the effectiveness of perforations in cased wellbores in under-pressured gas reservoirs, leading to uncertainties in production testing and hydro-fracturing, as they lack sensitivity and resolution to detect effective perforations prior to well testing or hydro-fracturing.
Innovation Solution
A well logging method using a sonde with an acoustic energy source and receivers to measure the travel time, attenuation, and reflection coefficient of Stoneley waves along the casing in cased wellbores, allowing for the determination of production capability of perforations and remedial actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional testing methods are used in under-pressured sand reservoirs, then production testing can be performed, but the diagnosis of perforation effectiveness is inadequate due to lack of sensitivity and resolution
Solution Approach 1:
The patent replaces conventional mechanical production testing methods with acoustic wave-based detection. By using acoustic energy sources and receivers to generate and detect Stoneley waves, the system achieves high-resolution perforation evaluation without relying on fluid flow measurements, thereby resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent utilizes the composite structure formed by the casing-cement-formation system as an acoustic waveguide. By analyzing how acoustic waves propagate through this composite structure and interact with perforations, the method achieves sensitive detection of perforation effectiveness that conventional single-method approaches cannot provide.
2Adaptability or versatility
If Stoneley wave logging is applied directly to formation walls in open hole wells, then formation intrinsic permeability can be assessed, but the method becomes inapplicable for cased wells with perforations
Solution Approach 1:
The patent introduces the casing as an intermediary medium for acoustic wave propagation. Instead of requiring direct contact with formation walls, the method uses the casing as a waveguide that transmits acoustic energy to and from the perforations, enabling perforation effectiveness measurement in cased wells while maintaining measurement precision.
Solution Approach 2:
The patent creates a universal acoustic detection method that works for both open hole and cased wells by adapting the wave propagation path. The same basic acoustic principles apply, but the implementation is modified to account for the presence of casing, allowing the technique to be universally applied across different well completion types.
3Measurement precision
If prior art methods requiring outgoing flowing fluid are used, then formation parameters can be estimated, but the method cannot be applied when production capability of perforations is uncertain or unknown
Solution Approach 1:
The patent performs preliminary acoustic characterization of perforations before production testing or hydro-fracturing. By evaluating perforation effectiveness in advance using acoustic waves, the method determines whether the formation requires stimulation or can proceed directly to production, eliminating the need for fluid flow-based methods in uncertain scenarios.
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
Enables precise assessment of perforation effectiveness, reducing uncertainties in production tests and hydro-fracturing by identifying effective and ineffective perforations, thereby optimizing gas production and preventing asset loss.
Implementation Method 1
Stoneley waves are a type of large-amplitude interface, or surface, waves generated by a well logging tool in a well borehole. Stoneley waves can propagate along a solid-fluid interface, such as along the walls of a fluid-filled borehole
Implementation Method 2
The acoustic energy receivers sense the time of travel of the imparted acoustic energy waves along the walls of the casing in the cased completed well
Implementation Method 3
The acoustic energy receivers also sense the amplitude of the acoustic energy waves along the walls of the casing in the cased completed well
Data Source
AI summary
Production capability of cased hole perforations in a cased completed well lined with a casing in an under-pressured gas producing reservoir is tested. A sonde of a dipole shear or array sonic (full waveform) acoustic well logging tool is moved in a well bore of the cased completed well in the reservoir across a depth interval of interest, which covers cased hole perforations zones in the reservoir. The well logging sonde has in it an acoustic energy source and acoustic energy receivers. Responses are logged at depth intervals of interest to the transit of Stoneley waves along the casing walls from the acoustic energy source to the acoustic energy receivers. Measures of characteristics (e.g., travel time and attenuation) of the Stoneley wave are obtained. The responses are then processed to indicate production capability of the cased hole perforations.