Proppant Pack Annulus Isolation for Fracture Control
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Solution Overview
Problem
Conventional methods for completing horizontal wells in tight reservoirs, such as cementing and mechanical isolation, limit production efficiency and increase costs, while open hole fracturing techniques face issues like unpredictable fracture propagation and proppant packing difficulties.
Innovation Solution
A method involving a production liner with a fluid pill containing lightweight proppant is used to create permeable yet impermeable packs in the annulus, allowing for discrete fracture placement and fluid communication, enabling efficient fracturing and production without cementing or mechanical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cementing the annulus is used to isolate fractures, then fracture isolation is achieved, but production efficiency is severely limited because cement prevents matrix production into the wellbore
Solution Approach 1:
The patent uses proppant material to create a porous pack in the annulus that allows fluid communication between the formation and wellbore while preventing fracturing fluid from traveling along the annulus. The porous structure enables matrix production to continue into the wellbore, resolving the contradiction between isolation and production efficiency.
Solution Approach 2:
The proppant pack acts as an intermediary material between the cemented annulus and the formation, providing both isolation of fracturing fluids and maintained production pathways. This mediator allows the system to achieve fracture isolation without blocking production routes.
2Reliability
If mechanical packers and ball operated frac sleeves are used for isolation, then fracture isolation is achieved, but significant additional cost is added to the wells
Solution Approach 1:
The patent employs proppant material as a low-cost, disposable isolation mechanism that eliminates the need for expensive mechanical packers and frac sleeves. The proppant pack provides sufficient isolation for the duration of fracturing operations without requiring complex mechanical components.
Solution Approach 2:
The invention extracts the isolation function from complex mechanical devices and implements it through simple proppant packing, removing unnecessary mechanical components and their associated costs while maintaining the essential isolation capability.
3Productivity
If open hole fracturing techniques are used, then production efficiency is improved, but fracture fluid leaks off to induced fractures lower in the well and propagation becomes unpredictable
Solution Approach 1:
The proppant pack creates a porous barrier that controls fluid flow through the annulus, preventing fracturing fluid from leaking off to lower fractures while maintaining predictable fracture propagation. The porous structure allows controlled fluid passage while blocking unwanted fluid migration.
4Device complexity
If a liner without annular flow containment mechanisms is used, then well completion simplicity is maintained, but fluid travels along the annulus and propagates along previous fractures
Solution Approach 1:
The proppant pack in the annulus serves as a simple yet effective flow containment mechanism that prevents fluid travel along the annulus without requiring complex mechanical devices. The porous material provides passive isolation that maintains fracture integrity while keeping the completion system simple.
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 allows for effective placement of multiple stage fractures in uncemented lined wellbores, enhancing production efficiency and reducing costs by maintaining fluid communication and preventing fracturing fluid from propagating along the annulus, while allowing formation fluids to be produced through the packed proppant.
Implementation Method 1
The proppant slurry is then slowly squeezed and packed into the annulus, the filtrate of the fluid pill leaking off to the surrounding formation
Implementation Method 2
The proppant slurry is then slowly squeezed and packed into the annulus
Implementation Method 3
The packed proppant is permeable to liquids but impermeable to fracturing proppants
Implementation Method 4
The packed proppant creates a porous material that prevents the fracturing treatment from traveling along the annulus
Data Source
AI summary
A production tubing comprising a liner is placed downhole in a wellbore. A fluid pill containing proppant is squeezed into the annulus between the formation and liner, thereby packing the proppant into the annulus, effectively isolating the annulus. The packed proppant is permeable to liquids but impermeable to fracturing proppants. After isolation of the annulus, the wellbore may be perforated using a resettable perforation assembly. Once perforating is complete, the wellbore is fractured. The presence of the packed proppant in the annulus generates resistance to the flow of fracturing fluid along the annulus, forcing the fracture to propagate down the perforation tunnels, while also allowing subsequent production fluids to be produced along the annulus.