Dynamic Viscosity Fracturing Fluid for Proppant Transport
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Solution Overview
Problem
Hydraulic fracturing with low viscosity fluids in tight gas reservoirs faces challenges such as proppant settling in manifold lines and pump equipment damage due to high specific gravity proppants and insufficient viscosity, leading to reduced fracture area and increased treating pressures.
Innovation Solution
A method involving blending water with a viscosifying polymer and crosslinking agent to create a fracturing fluid with high viscosity at the wellhead, which decreases rapidly upon entering the reservoir, minimizing proppant settling and equipment damage, while maintaining effective fracture conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low viscosity fluids are used for fracturing tight gas reservoirs, then fracture area increases and fluid efficiency improves, but proppant settling occurs in manifold lines and pump equipment damage increases
Solution Approach 1:
The patent applies a dynamic viscosity approach where the fracturing fluid exhibits high viscosity during pumping to prevent proppant settling, then rapidly decreases viscosity after entering the formation to maximize fracture area. This time-dependent and location-dependent viscosity change resolves the contradiction between maintaining proppant suspension and creating large fracture areas.
Solution Approach 2:
The patent changes the viscosity parameter of the fracturing fluid from high to low after injection into the formation. This parameter change is achieved through the use of viscosifying polymers that degrade or unwind upon contact with formation fluids, allowing the fluid to transition from a proppant-suspending state to a low-viscosity fracture-propagating state.
2Strength
If high specific gravity proppants are used, then fracture conductivity increases, but proppant settling in manifold lines occurs and pump equipment damage increases
Solution Approach 1:
The patent introduces a viscosifying polymer as an intermediary substance that mediates between the high specific gravity proppant and the pumping system. The polymer creates a viscous matrix that suspends the heavy proppant during transport, preventing settling in manifold lines and pump equipment, while still allowing the proppant to settle effectively in the formation to create conductive fractures.
3Reliability
If high viscosity fracturing fluid is used, then proppant transport stability improves, but fracture area decreases and treating pressure increases
Solution Approach 1:
The patent implements a periodic action pattern where the fluid viscosity cycles between high and low states. During the injection phase, high viscosity maintains proppant suspension and transport stability. After injection into the formation, the viscosity rapidly decreases to allow fracture propagation and maximize fracture area, thereby resolving the contradiction between transport stability and fracture area.
4Reliability
If conventional viscosifying polymers are used, then proppant suspension improves, but formation damage increases due to polymer residue
Solution Approach 1:
The patent uses polymers whose molecular configuration changes from extended to coiled states, or whose crosslinking density changes, allowing the fluid to maintain high viscosity during pumping then rapidly reduce viscosity after injection. This parameter change minimizes polymer residue in the formation, reducing formation damage while maintaining proppant suspension during transport.
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
The method enhances proppant transport and placement, reduces pump failures, and achieves efficient fracture stimulation with lower polymer loading, minimizing formation damage and increasing fluid efficiency in low permeability reservoirs.
Implementation Method 1
a fracturing fluid which contains a hydratable polymer and a crosslinking agent wherein the apparent viscosity of the fluid decreases distally from the entrance site of the reservoir
Implementation Method 2
a fracturing fluid which contains a hydratable polymer
Implementation Method 3
the viscous nature of the fracturing fluid enables the fluid to transport the proppant to the perforating sites in the wellbore while minimizing settling
Implementation Method 4
a fracturing treatment fluid containing a solid proppant is injected into the formation at a pressure sufficiently high enough to cause the formation or enlargement of fractures in the reservoir
Data Source
AI summary
Subterranean formations, such as tight gas formations, may be subjected to hydraulic fracturing by introducing into the formation a fracturing fluid of an aqueous fluid, a hydratable polymer, a crosslinking agent and proppant. The fracturing fluid is prepared in a blender and then pumped from the blender into the wellbore which penetrates the formation. The fluid enters the reservoir through an entrance site. The apparent viscosity of the fluid decreases distally from the entrance site such that at least one of the following conditions prevails at in situ conditions:(a) the apparent viscosity of the fracturing fluid 100 feet from the entrance site is less than 10 percent of the apparent viscosity of the fracturing fluid at the entrance site;(b) the apparent viscosity of the fracturing fluid 15 minutes after introduction into the entrance site is less than 15% of the apparent viscosity of the fracturing fluid at the entrance site; or(c) the apparent viscosity of the fracturing fluid is less than 10 cP within 15 minutes after being introduced through the entrance site.