Pad-Wide CO2 Flow Scheduling for Zipper Hydraulic Fracturing
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Solution Overview
Problem
Current hydraulic fracturing methods, including zipper fracturing, suffer from low hydrocarbon recovery factors and significant loss of carbon dioxide (CO2) to the atmosphere due to cyclic operation during stage changes, limiting the amount injected and causing environmental pollution.
Innovation Solution
A method for continuous CO2 injection during zipper hydraulic fracturing operations, alternating between perforation, CO2 injection, and proppant-carrying fracturing fluid injection to maintain continuous CO2 flow, reducing atmospheric emissions and enhancing CO2 utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cyclic CO2 injection is used during zipper fracturing operations, then CO2 can be injected into multiple wells, but significant CO2 is lost to the atmosphere during stage changes
Solution Approach 1:
The patent implements continuous CO2 injection by alternating between injecting CO2 into different wells in the pad, ensuring that CO2 injection never stops. When one well is being fractured, CO2 is simultaneously injected into another well, eliminating idle time and atmospheric losses associated with cyclic operation. This continuous action resolves the contradiction by maintaining high injection volume while preventing CO2 loss to the atmosphere.
Solution Approach 2:
The patent uses periodic switching between multiple wells to maintain continuous CO2 injection. Instead of injecting into a single well cyclically (which causes loss during transitions), the system periodically alternates between multiple wells, creating a staggered injection pattern that eliminates idle time and atmospheric losses while maintaining overall continuous injection action.
2Productivity
If conventional hydraulic fracturing is used, then hydrocarbon production can be achieved, but recovery factor remains low (less than 5%)
Solution Approach 1:
The patent changes the physical and operational parameters of the fracturing process by introducing continuous CO2 injection alongside conventional fracturing. This parameter change (adding continuous CO2) modifies the fracture network characteristics and hydrocarbon flow dynamics, thereby improving the recovery factor from the conventional less than 5% to higher levels while maintaining productive hydrocarbon extraction.
Solution Approach 2:
The patent creates a composite fracturing system that combines conventional fracturing fluid with CO2 injection. This composite approach integrates multiple mechanisms (proppant support, CO2 pressure maintenance, potential carbonate reactions) into a unified system that enhances both hydrocarbon production and recovery factor simultaneously.
3Ease of operation
If CO2 injection is interrupted during well stage changes, then operational flexibility is maintained, but atmospheric pollution increases
Solution Approach 1:
The patent prepares multiple wells in advance for sequential CO2 injection. By having multiple wells ready and staged for injection, the system can switch between wells without interrupting CO2 injection, thereby maintaining operational flexibility while preventing atmospheric pollution. The preliminary preparation of multiple wells enables continuous operation during stage changes.
Solution Approach 2:
The patent uses multiple wells as intermediaries to maintain continuous CO2 injection. When one well is being fractured, CO2 is simultaneously injected into another well, which acts as an intermediary receiver. This intermediary approach allows the system to transition between wells smoothly without interrupting injection, thereby maintaining both operational flexibility and environmental cleanliness.
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
Reduces atmospheric CO2 leakage and increases the amount of CO2 injected, improving hydrocarbon recovery by maintaining continuous CO2 flow and creating more complex fracture networks.
Implementation Method 1
pumping of large quantities of fracturing fluid into a subterranean formation under high hydraulic pressure to promote the formation of one or more fractures
Implementation Method 2
promote the formation of one or more fractures within the matrix of the formation and to create high-conductivity flow paths
Implementation Method 3
Proppant particles are often included in the fracturing fluid. Once the fracturing fluid has been pumped into the subterranean formation, such proppant particles are transported into the fractures and settle therein
Implementation Method 4
the proppant particles remaining in the fractures keep the fractures open by preventing them from collapsing
Implementation Method 5
facilitating the flow of hydrocarbon fluids from the fractured formations into the wellbore through the propped fractures
Data Source
AI summary
A method for hydraulically fracturing a plurality of wells from a pad. The method comprises, for each of the plurality of wells, alternating between perforation, injection of CO2, and injection of proppant-carrying fracturing fluid such that each stage of each well is hydraulically fractured in sequence. The method also comprises maintaining continuous CO2 injection for the pad as a whole.