Intermittent Fracturing for Complex Crack Networks
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Solution Overview
Problem
Conventional hydraulic fracturing methods for tight sandstone and shale reservoirs result in low complexity cracks, leading to rapid decline in oil well production and require expensive, high-risk equipment, limiting their effectiveness and safety.
Innovation Solution
An intermittent fracturing method that uses a fracturing truck, signal detecting vehicle, and sand blending truck to pump fracturing fluid and sand-carrying fluid into the well, forming complex cracks by repeating cycles of pressure pumping and under-pressure shut-in until microseismic signals are detected, reducing equipment requirements and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional hydraulic fracturing is used, then the fracturing process is simple and equipment requirements are low, but the crack complexity is low and production per well decreases rapidly
Solution Approach 1:
The patent applies periodic action by implementing intermittent fracturing with multiple cycles of pumping and shut-in. The fracturing process is divided into several stages where fracturing fluid is pumped to create cracks, then pumping is stopped to allow crack extension and pressure equalization. This cyclic process repeats multiple times to build a complex crack network system, transforming the simple continuous pumping of conventional methods into a periodic multi-stage process that achieves higher crack complexity without requiring complex additional equipment.
2Productivity
If high energy gas fracturing is used, then multiple cracks can be formed, but the equipment requirements are very high and safety risks are greater
Solution Approach 1:
The patent employs cheap short-living objects by using readily available fracturing fluids (water-based slickwater or sand-carrying fracturing fluid) instead of expensive specialized equipment like rocket propellants, supercritical CO2 systems, or liquid nitrogen tanks. The fracturing fluid is pumped through conventional pumping equipment already present at most oilfields, eliminating the need for complex gas generation, storage, and delivery systems. This approach achieves multiple crack formation through intelligent process control rather than through expensive specialized equipment.
Solution Approach 2:
The patent applies mechanics substitution by replacing the mechanical/chemical energy systems of high-energy gas fracturing (rocket engines, propellant combustion, supercritical fluid expansion) with a simple hydraulic pumping system. Instead of using chemical reactions or phase changes to generate fracturing energy, the patent uses conventional hydraulic fracturing pumps to deliver fracturing fluid at controlled rates and pressures, combined with intelligent shut-in timing based on microseismic signal detection to achieve complex crack network formation.
3Productivity
If supercritical carbon dioxide fracturing or liquid nitrogen fracturing is used, then a multi-crack system can be created, but the gas sources are not stable and safety is hard to ensure
Solution Approach 1:
The patent applies self-service by using microseismic signal detection to automatically control the fracturing process. Microseismic sensors monitor crack propagation in real-time, and when crack extension is detected, the system automatically adjusts pumping rates or initiates shut-ins without requiring external intervention or complex external control systems. This self-monitoring and self-adjusting capability ensures reliable and safe operation by responding directly to the actual state of the reservoir, eliminating the need for unstable external gas sources.
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 method creates a complex crack network in tight sandstone and shale reservoirs, enhancing oil well production while minimizing equipment needs and costs, making it a cost-effective solution for improving well productivity.
Implementation Method 1
pumping a fracturing fluid into an oil well to enter a reservoir by means of a fracturing truck, continuing pumping the fracturing fluid into fractured cracks after a pumping pressure has reached a preset pressure
Implementation Method 2
stopping the shut-in operation when a signal detecting vehicle cannot receive an obvious microseismic signal in the under-pressure shut-in process
Data Source
AI summary
A fracturing method for creating a complex crack network by intermittent fracturing on site, which relates to oil and gas field development, and comprises the following steps: pumping a fracturing fluid into an oil well to enter the reservoir, continuing pumping the fracturing fluid into fractured cracks after a pumping pressure has reached a preset pressure, and stopping pumping the fracturing fluid after a preset condition has been reached; performing under-pressure shut-in for the oil well; stopping the shut-in operation when a signal detecting vehicle cannot receive an obvious microseismic signal in the under-pressure shut-in process; repeating the above three steps multiple times; pumping the fracturing fluid into the oil well to enter the reservoir by the fracturing truck until an amount of the pumped in fracturing fluid reaches a design pump-in liquid amount; pumping a sand-carrying fluid into the oil well to enter the reservoir by means of a sand blending truck and the fracturing truck after the amount of the pumped in fracturing fluid has reached the design pump-in liquid amount, and stopping pumping the sand-carrying fluid after the pumped in sand-carrying fluid has reached a preset sand adding amount.