Hydraulic Fracture Profile Prediction for Multi-Layer Height Control
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Solution Overview
Problem
Hydraulic fracturing in multi-layered formations is challenging due to non-constant horizontal in-situ stresses and hydrostatic fluid pressures, leading to uncontrolled fracture propagation into non-production zones and reduced operational efficiency.
Innovation Solution
A data processing system uses one-dimensional high-order elements to discretize multi-layer formations, calculating stress intensity factors at fracture tips, optimizing pump schedules, and selecting proppant sizes to control fracture height and width, accounting for depth-dependent stresses and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic fracturing is performed in multi-layered formations with non-constant horizontal in-situ stresses, then fracture stimulation effectiveness is improved, but fracture height control becomes difficult causing propagation into non-production zones
Solution Approach 1:
The multi-layered formation is divided into discrete layers, each with its own stress and pressure characteristics. The fracture propagation is analyzed layer-by-layer using one-dimensional high-order elements, allowing precise control and prediction of fracture height in each layer while accounting for non-constant in-situ stresses
Solution Approach 2:
The system performs preliminary calculation of depth-dependent horizontal in-situ stresses and hydrostatic fluid pressures before fracturing operations. This advance computation of stress profiles enables optimization of pump schedules and proppant selection to control fracture height before actual fracturing begins
2Ease of manufacture
If constant horizontal in-situ stress and linear hydrostatic pressure distribution are assumed, then calculation simplicity is improved, but prediction accuracy of fracture profiles deteriorates
Solution Approach 1:
The system transitions from assuming constant stress and linear pressure to using depth-dependent variable parameters. One-dimensional high-order elements are employed to model the non-linear distribution of horizontal in-situ stresses and hydrostatic pressures, significantly improving fracture profile prediction accuracy while maintaining computational efficiency through numerical integration methods
3Productivity
If fracture height is allowed to grow uncontrolled, then maximum production performance is improved, but fractures propagate into non-production zones causing negative consequences
Solution Approach 1:
The system uses calculated stress intensity factors at fracture tips as feedback to predict fracture propagation behavior. This information feeds back into optimizing pump schedules and selecting proppant sizes to control fracture height, creating a closed-loop system that maximizes production while preventing unwanted propagation through iterative refinement of fracturing parameters
Data Source
AI summary
Techniques for fracturing a formation include receiving a data representing depth-dependent horizontal in-situ stress and a fracture toughness for one or more layers of the formation, predicting a hydraulic fracture profile within the formation, and pumping a fluid into a wellbore to fracture the formation at a perforation location based on the predicted hydraulic fracture profile. Predicting the hydraulic fracture profile can include determining a location of an upper portion of the fracture profile when an upper fracture tip stress intensity factor satisfies an upper fracture tip propagation condition, and determining a location of a lower portion of the fracture profile when a lower fracture tip stress intensity factor satisfies a lower fracture tip propagation condition. Predicting the hydraulic fracture profile can include determining a depth-dependent width profile of the hydraulic fracture based on the determined locations of the upper and lower portions.