Lightweight Sand Plugs for Isolation in Highly Deviated Wells
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Solution Overview
Problem
In subterranean stimulation operations, highly deviated well bores present challenges in isolating multiple production zones due to varying fracture gradients, leading to ineffective stimulation treatments as traditional sand plugs and mechanical packers often fail to provide adequate isolation, especially in horizontal wells where zones closer to the wellhead are not properly isolated.
Innovation Solution
The method involves using a sand plug comprising lightweight particulates with a specific gravity below 1.25, suspended in a carrier fluid, pumped into the well bore at controlled rates and pressures, with the squeeze technique applied to ensure effective isolation by forming a hydraulic seal that spans the entire well bore diameter, even in highly deviated sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sand plugs are used in highly deviated well bores, then the well bore can be plugged, but the sand plugs fail to fully isolate zones due to gravitational settling
Solution Approach 1:
The patent changes the density parameter of the sand plug by using lightweight particulates with specific gravity less than 1.25, which matches or exceeds the density of formation fluids. This prevents gravitational settling in highly deviated well bores and maintains plug integrity throughout the treatment process.
Solution Approach 2:
The patent uses composite lightweight particulates that combine low density with adequate mechanical strength and chemical stability. These composite materials provide both the buoyancy needed to prevent settling and the structural integrity needed to maintain an effective hydraulic seal.
2Reliability
If mechanical packers and bridge plugs are used to isolate production zones, then zone isolation can be achieved, but the devices are prone to sticking and failure in open perforations
Solution Approach 1:
The patent replaces mechanical packers and bridge plugs with a hydraulic sand plug system. Instead of relying on mechanical expansion and setting mechanisms that can stick or fail, the invention uses a fluid-based hydraulic seal that adapts to the well bore geometry and provides reliable isolation without mechanical sticking issues.
Solution Approach 2:
The sand plug acts as an intermediary material that creates a hydraulic barrier between zones. Rather than using a mechanical device that must physically contact and seal against the well bore wall, the sand plug suspends in the carrier fluid and forms a distributed hydraulic seal throughout the treatment fluid column.
3Productivity
If stimulation operations are conducted simultaneously on multiple production zones, then efficiency is improved, but fracturing fluids preferentially enter depleted zones with lower fracture gradients
Solution Approach 1:
The patent segments the well bore into isolated zones using sand plugs placed between production zones. This allows each zone to be stimulated independently with tailored fracturing treatments, preventing fluid diversion to depleted zones and ensuring each zone receives the appropriate stimulation intensity and fluid type.
Solution Approach 2:
The sand plugs are placed in advance before stimulation operations to pre-establish hydraulic isolation between zones. This preliminary action ensures that when multiple zones are stimulated, the fracturing fluids remain contained within each zone and do not preferentially flow into depleted adjacent zones.
4Reliability
If sand concentration in treatment fluid is increased to form a sand plug, then downstream zones can be isolated, but traditional sand plugs fail to span the entire well bore diameter in highly deviated sections
Solution Approach 1:
The patent changes the density parameter by using lightweight particulates that match or exceed formation fluid density, preventing the sand plug from settling away from the well bore centerline in highly deviated sections. This maintains the plug's cross-sectional area and ensures it spans the entire well bore diameter for effective hydraulic sealing.
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 allows for successful isolation of downstream zones from upstream zones in highly deviated well bores, enabling independent stimulation of multiple zones along the well bore, improving hydrocarbon production by ensuring that fracturing fluids do not reach isolated zones, thus enhancing the effectiveness of stimulation treatments.
Implementation Method 1
providing a sand plug comprising lightweight particulates having a specific gravity of below about 1.25
Implementation Method 2
allow it to settle into a portion of the well bore adjacent the zone to be isolated
Data Source
AI summary
Methods of isolating portions of a subterranean formation adjacent to a highly deviated well bore having a downstream end and an upstream end and substantially filling a first zone with a sand plug comprising lightweight particulates having a specific gravity of below about 1.25 so as to substantially isolate the first zone from the second zone wherein the first zone is located closer to the downstream end of the wellbore than the second zone.