Microseismic Data Analysis via Geomechanical Stress Modeling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for analyzing microseismic data from hydraulic fracturing in oil and gas wellbores face significant errors and scatter due to noise and unrealistic geomechanical interpretations, making it difficult to accurately determine the orientation of hydraulic fracture planes.
Innovation Solution
A method employing a geomechanical model to identify the most likely slippage planes based on shear and normal stress ratios, which are then validated against microseismic event amplitudes and statistically compared to randomized data to ensure internal consistency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a simplistic approach comparing amplitudes of primary and secondary elastic waves is used to infer failure plane orientation, then the interpretation process is simple, but the results contain great error and scatter due to noise and are inconsistent with realistic geomechanical bounds
Solution Approach 1:
The patent transforms the interpretation from directly using raw amplitude ratios to using a geomechanical model that incorporates stress state parameters (vertical stress, horizontal stresses, pore pressure) to calculate shear stress and normal stress on potential failure planes. This parameter transformation allows the system to filter out noise while maintaining geological realism.
Solution Approach 2:
The patent introduces a geomechanical model as an intermediary between the observed microseismic data and the inferred failure plane orientation. This model acts as a mediator that translates amplitude observations into geomechanically consistent stress states, thereby resolving the contradiction between simplicity and accuracy.
2Productivity
If external information is used to estimate plane slippage angle from external sources, then the interpretation can proceed, but the results may not be internally consistent with the measured microseismic data
Solution Approach 1:
The patent implements a feedback mechanism where the geomechanical model is iteratively adjusted to match the observed amplitude ratios. The model predictions are compared with actual measurements, and the stress state parameters are refined until consistency is achieved. This feedback loop ensures both internal consistency and reliability of the interpretation.
Solution Approach 2:
The patent makes the interpretation dynamic by allowing the geomechanical model parameters to be adjusted based on the observed data. Rather than using fixed external estimates, the model adapts to the specific conditions of each microseismic event, improving both reliability and internal consistency.
3Quantity of substance
If microseismic data with large scatter and uncertainty is used directly, then all available data is utilized, but the precise spatial location and orientation of failure planes cannot be determined accurately
Solution Approach 1:
The patent transforms the problem from directly interpreting noisy amplitude ratios to inverting a geomechanical model that relates stress state parameters to observed amplitudes. This parameter transformation allows the system to utilize all available data while filtering out noise through the physical constraints of the geomechanical model.
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 provides a reliable and internally consistent interpretation of microseismic data, reducing the impact of noise and scatter, and can be used to improve hydraulic fracture modeling and simulation, distinguishing between fluid-related microseismicity and movement on pre-existing fault planes.
Implementation Method 1
applying the geomechanical model to the postulated orientation to determine the resulting shear stress and normal stress applied to the postulated orientation
Implementation Method 2
seismic traces are recorded, which include both the longitudinal and transverse waves travelling through the formation
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method of analyzing measured microseismic events obtained from monitoring induced hydraulic fracturing of underground geological formations, the method involving (a) postulate a geomechanical model for the region bounding the microseismic events, the model including the parameters vertical stress, reservoir pore pressure, minimum horizontal stress and the orthogonal horizontal stress, (b) select a microseismic event and (c) for the selected microseismic event assume an associated slippage plane with a postulated orientation, (d) apply the geomechanical model to the postulated orientation to determine the resulting shear stress and normal stress applied to the postulated orientation, (e) repeat steps (c) and (d) to produce a number of postulated slippage planes each with their own shear stress and normal stress attributable to them, (f) select the fracture plane having the highest ratio of shear stress to normal stress as being the fracture plane most likely to be representative of a real slippage plane consistent with the geomechanical model, (g) repeat steps (b) to (f) to analyze a number of microseismic events to generate a slippage plane most likely to be representative of a real slippage plane for each microseismic event is provided.