ULW Deformable Core Fluid Pill for Horizontal Wellbore Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In horizontal wellbores, existing methods for hydraulically isolating zones are inefficient due to gravitational settling of sand or proppant, which compromises the formation of a stable sand plug, and require time-consuming and expensive coiled tubing operations.
Innovation Solution
A fluid pill containing an ultra lightweight (ULW) deformable core coated with a viscosifying polymer and crosslinking agent is pumped into the wellbore, allowing the core to remain suspended and form a highly viscous gel that bridges off to create a fluid-impermeable plug, enhancing isolation without the need for separate shipping of additives and reducing surface operating space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sand or proppant is used to build a plug in a horizontal wellbore, then hydraulic isolation of zones is achieved, but gravitational settling causes the plug to settle along the bottom creating voids that compromise isolation
Solution Approach 1:
Ultra lightweight proppant or neutrally buoyant proppant is used to counteract gravitational settling. The proppant's density is matched to the fracturing fluid or made sufficiently lightweight that it remains suspended rather than settling to the bottom of the horizontal wellbore, thereby preventing void formation and ensuring uniform plug composition throughout the isolation zone.
Solution Approach 2:
The density parameter of the proppant is changed from conventional sand density to ultra lightweight or neutrally buoyant density. This parameter change allows the proppant to remain suspended in the fluid pill during the fracture closure period, preventing gravitational settling and ensuring uniform distribution throughout the wellbore cross-section for reliable hydraulic isolation.
2Reliability
If the fluid pill is pumped at a slow rate to keep sand suspended, then isolation is improved, but treatment time increases
Solution Approach 1:
By using ultra lightweight or neutrally buoyant proppant that naturally resists gravitational settling, the fluid pill can be pumped at higher rates without the proppant settling out. This eliminates the need for slow pumping rates while still maintaining suspended proppant for effective bridging and plug formation, thereby reducing overall treatment time.
Solution Approach 2:
The proppant is pre-selected to have ultra lightweight or neutrally buoyant properties before the fracturing treatment begins. This preliminary characterization of the proppant ensures that it will remain suspended during rapid pumping, allowing the treatment to proceed at optimal speeds without compromising plug formation reliability.
3Reliability
If coiled tubing is used to push and set a bridge plug in a horizontal wellbore, then hydraulic isolation is achieved, but the operation becomes time-consuming and expensive
Solution Approach 1:
The fracturing fluid itself, containing ultra lightweight or neutrally buoyant proppant, serves the dual function of both fracturing the formation and forming the isolation plug. The proppant automatically bridges off at the fracture entrance due to its suspended state and the partial closure of fractures, eliminating the need for separate bridge plug deployment operations using coiled tubing or wirelines.
Solution Approach 2:
The fracturing fluid is given multiple functions: it fractures the formation, transports proppant into the fracture, and simultaneously forms the hydraulic isolation plug at the fracture entrance. This multi-functionality eliminates the need for separate isolation devices and operations, significantly improving treatment efficiency and reducing costs.
4Reliability
If conventional sand plug construction is used, then hydraulic isolation is achieved, but separate shipping of additives and surface operating space is required
Solution Approach 1:
The ultra lightweight or neutrally buoyant proppant, viscosifying agent, and crosslinking agent are combined into a single integrated fluid pill formulation. This merging of components eliminates the need for separate shipping of additives and reduces surface operating space requirements, as all necessary materials are pre-combined and ready for direct pumping into the wellbore.
Solution Approach 2:
A composite fluid pill is created that integrates ultra lightweight or neutrally buoyant proppant with viscosifying agents and crosslinking agents. This composite material provides both the suspension characteristics needed for effective plug formation and the gelation properties required for stable isolation, while simplifying logistics by combining multiple components into one shipment.
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 effectively forms a stable plug that prevents fluid flow into isolated zones, reducing waiting time for fracture closure and plug formation, and allows for more efficient multizone fracturing treatments in horizontal wellbores.
Implementation Method 1
Constructing a sand plug within a horizontal wellbore is difficult since gravitational settling of sand or proppant in the wellbore causes the plug to settle along the bottom of the wellbore
Implementation Method 2
a fluid pill containing an ultra lightweight (ULW) deformable core coated with a viscosifying polymer and crosslinking agent is pumped into the wellbore, allowing the core to remain suspended and form a highly viscous gel that bridges off to create a fluid-impermeable plug
Data Source
AI summary
A method for building a plug in a horizontal wellbore using a fluid pill containing a suspended well treatment agent. The well treatment agent contains an ultra lightweight (ULW) deformable core and a viscosifying polymer and crosslinking agent coated onto the core. The fluid pill is pumped into the wellbore at the end of a fracturing treatment. The fluid pill is displaced by a displacement fluid and the fluid pill transforms to a thickened gel. The thickened gel is formed by the in-situ reaction of the viscosifying polymer and crosslinking which become disassociated from the ULW deformable core. The gelled fluid containing the ULW deformable core assists in the bridging of the ULW deformable core and forming the bridge plug.