Sequential Oil and Water Fracturing Fluids for Formation Swelling Control
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Solution Overview
Problem
Hydraulic fracturing with water-based fluids often causes formation swelling, clay migration, and conductivity issues due to water sensitivity, leading to damage in subterranean formations.
Innovation Solution
Using an oil-based fracturing fluid initially, followed by a water-based fluid, with additives to change the formation's wettability to oil-wet or omniphobic, reducing water absorption and swelling, and incorporating fluid loss agents to prevent water infiltration, while maintaining reservoir permeability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water-based fracturing fluid is used, then the fracturing process can be performed with conventional fluids, but formation swelling, clay migration, and conductivity issues occur due to water sensitivity
Solution Approach 1:
An oil-based fracturing fluid is injected into the formation before the water-based fracturing fluid to modify the wettability of the formation. This preliminary action prepares the formation by making it oil-wet, which prevents water absorption and subsequent formation swelling and clay migration when the water-based fluid is later injected.
Solution Approach 2:
The oil-based fracturing fluid acts as an intermediary between the water-based fracturing fluid and the water-sensitive formation. It creates a protective interface that prevents direct contact between water and the formation, thereby eliminating harmful effects while allowing the water-based fracturing process to proceed.
2Productivity
If water-based fracturing fluid is used, then the fracturing operation can proceed, but reservoir permeability and conductivity are reduced due to water absorption and formation damage
Solution Approach 1:
The oil-based fluid is injected first to modify the formation wettability to oil-wet conditions. This preliminary modification ensures that when the water-based fracturing fluid is subsequently injected, the formation does not absorb water, thereby maintaining reservoir permeability and conductivity while still allowing the fracturing operation to proceed effectively.
Solution Approach 2:
The oil-based fracturing fluid serves as a protective intermediary layer between the water-based fracturing fluid and the water-sensitive formation. This intermediary prevents water from entering the formation pores, thus preserving the formation's permeability and conductivity while enabling the water-based fracturing process.
3Object-affected harmful factors
If formation wettability is modified to oil-wet, then water absorption is reduced and formation swelling is prevented, but additional additives and process complexity are required
Solution Approach 1:
The wettability of the formation is modified by changing the chemical parameters of the fracturing fluid from water-based to oil-based. This parameter change alters the interfacial properties between the fracturing fluid and the formation, making the formation oil-wet and thereby reducing water absorption and formation swelling. The process uses commercially available oil-based fracturing fluids with standard additives, maintaining practical simplicity.
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 minimizes the impact on the subterranean formation during fluid switching, enhances fluid recovery, and maintains permeability by using oil-based fluids as a fluid loss agent and wettability modifier, reducing the need for additional additives and preventing formation swelling.
Implementation Method 1
Additives to the oil-based fluids can be used to change the wettability of a subterranean formation to oil-wet or omniphobic
Implementation Method 2
The oil-based fluid also behaves as a fluid loss agent and limits or prevents water from getting into the formation solids
Implementation Method 3
fluid loss agents can also be included in oil-based fluid to prevent minimum imbibition of oil or other fracturing fluid in the formation thereby keeping the water saturation of the formation low
Data Source
AI summary
A method for hydraulic fracturing of a subterranean formation includes injecting an oil-based fracturing fluid into the subterranean formation through a well. The method also includes injecting a second fracturing fluid, for example a water-based fracturing fluid, into the subterranean formation through the well after completion of the injection of the oil-based fracturing fluid.