Ultra Lightweight Proppant Plug Formation in Horizontal Wellbores
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Solution Overview
Problem
Existing methods for isolating zones in horizontal wellbores using bridge plugs are inefficient and costly due to difficulties in maintaining sand or proppant suspension, leading to incomplete plug formation and requiring remedial operations.
Innovation Solution
A method involving a fluid pill with a high concentration of ultra lightweight proppant, which remains suspended during fracturing fluid displacement, allowing the proppant to bridge off and form a plug within the wellbore by varying the pumping rate and using neutrally buoyant or larger diameter proppants to prevent settling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sand or proppant is used in fracturing fluid, then the proppant can be pumped into the wellbore, but the proppant settles during displacement causing incomplete plug formation
Solution Approach 1:
The patent changes the density parameter of the proppant by using ultra lightweight proppant (specific gravity 1.05-1.30) instead of conventional proppant (specific gravity 2.65). This parameter change allows the proppant to remain suspended in the fracturing fluid during displacement operations, preventing settling and ensuring complete plug formation at the target zone.
Solution Approach 2:
The patent applies the anti-weight principle by using proppant with density matching or slightly less than the fracturing fluid density. This creates neutral buoyancy or slight positive buoyancy, counteracting the gravitational settling that occurs with conventional heavier proppant, thereby maintaining suspension stability throughout the wellbore displacement process.
2Reliability
If bridge plugs are used to isolate zones in horizontal wellbores, then hydraulic isolation can be achieved, but the operation becomes time-consuming and expensive
Solution Approach 1:
The patent extracts the isolation function from the mechanical bridge plug and implements it through a sand/proppant plug built in-situ within the wellbore. This eliminates the need to run, set, and later retrieve mechanical bridge plugs, significantly reducing operation time and cost while maintaining hydraulic isolation effectiveness.
Solution Approach 2:
The sand/proppant plug is built using the fracturing fluid itself as the carrier medium. The proppant is pumped with the fracturing fluid and self-accumulates at the target zone to form the isolation plug, eliminating the need for separate isolation operations and equipment.
3Ease of operation
If wireline is used to pump bridge plugs into horizontal wellbores, then the plug can be inserted, but fracturing fluid is displaced into the formation causing adverse effects
Solution Approach 1:
The patent uses a sand/proppant plug as an intermediary mechanism to achieve isolation. The plug is built by pumping proppant with fracturing fluid that remains in the wellbore, rather than using wireline to push a bridge plug that would displace fracturing fluid into the formation. This intermediary approach eliminates the harmful fluid displacement while achieving the same isolation goal.
4Reliability
If coiled tubing is used to push bridge plugs into horizontal wellbores, then isolation can be achieved, but the process becomes expensive requiring tubing removal between treatments
Solution Approach 1:
The patent extracts the isolation function from complex mechanical bridge plugs requiring coiled tubing deployment and retrieval. Instead, a simple sand/proppant plug is built in-situ using standard fracturing equipment, eliminating the need for coiled tubing and associated rig-up/rig-down operations between treatments.
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 effectively builds a stable sand or proppant plug within the wellbore, reducing the need for costly remedial operations and allowing for a wider range of fracturing fluids, while maintaining proppant suspension and promoting bridging off at perforations.
Implementation Method 1
utilizing a fluid pill containing a high concentration of ultra lightweight proppant in order to form a proppant plug
Implementation Method 2
The use of an ultra lightweight proppant helps the proppant to remain suspended within the fluid pill while it is stationary within the wellbore
Implementation Method 3
the suspended sand in the fluid pill begins to bridge off against the fractures
Implementation Method 4
the ultra lightweight proppant to bridge off against the fractures and/or the perforations tunnels
Data Source
AI summary
An improved method for building a plug in a horizontal wellbore using a fluid pill pumped into the wellbore at the end of a fracturing treatment. The fluid pill includes a high concentration of an ultra lightweight proppant, such as a neutrally buoyant proppant or an ultra lightweight proppant mixture. The fluid pill is pumped down the wellbore until it almost reaches fractures within a zone of interest. The pumping is then ceased or reduced, allowing the fractures to partially close. The ultra lightweight proppant remains suspended within the fluid pill while stationary. The pumping is then resumed at a very slow rate or as a short pump burst, thus causing the proppant in the fluid pill to bridge off until a bridge plug is formed.