Nested Well Completion String for Multi-Zone Gravel Pack Trips
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Solution Overview
Problem
The repetitive trips required for completing multiple zones in a wellbore increase operational risks, rig time, and personnel hours, making existing systems inefficient and costly.
Innovation Solution
A completion system comprising an outer completion string and an inner service string with integrated downhole flow control, allowing for the deployment of all completion hardware in a minimum number of trips, including a lower completion string for sand control and upper completion for production, with the inner service string performing operations without moving within the outer string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple work strings are run into and out of the wellbore for completing different zones, then each zone can be completed with dedicated equipment, but operational risks, rig time, and personnel hours increase
Solution Approach 1:
The patent implements nesting by placing the inner service string inside the outer completion string. The inner service string can be deployed and retrieved independently while the outer completion string remains in place, allowing multiple services to be performed without repeated trips. This nested configuration enables one equipment system to contain another, resolving the contradiction between zone completion capability and rig time by allowing sequential operations through a single deployment.
Solution Approach 2:
The outer completion string is designed with universal functionality to serve multiple purposes: it acts as both the production completion string and the conduit for deploying inner service strings for various wellbore services. This multi-functional design eliminates the need for separate equipment deployments for different zones and services, thereby reducing rig time while maintaining adaptability for completing multiple zones.
2Adaptability or versatility
If multiple work strings are run into and out of the wellbore for completing different zones, then each zone can be completed with dedicated equipment, but operational risks and personnel hours increase
Solution Approach 1:
The nested configuration allows the inner service string to be deployed within the protected environment of the outer completion string. This reduces operational risks by minimizing the number of times equipment must be run into and out of the wellbore, thereby reducing exposure to downhole conditions and potential failure modes associated with repeated trips.
Solution Approach 2:
The outer completion string is installed first and remains in place as a permanent or semi-permanent structure. This preliminary action creates a stable platform that eliminates the need for subsequent trips to re-enter the wellbore for service operations, thereby reducing operational risks associated with repeated equipment deployment and retrieval.
3Ease of operation
If the inner service string moves within the outer completion string to perform operations, then flexibility in performing services is improved, but system complexity increases
Solution Approach 1:
The patent resolves the complexity issue by implementing a straightforward nested configuration where the inner service string simply moves vertically within the outer completion string. This elegant solution provides operational flexibility without requiring complex control mechanisms, as the inner string can be deployed to different depths to service different zones while maintaining a relatively simple overall system architecture.
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3C
AI summary
A system includes an outer completion string, an inner service string configured to connect within the outer completion string, and an upper completion. The outer completion string includes at least one isolation packer, a sand control assembly and a gravel pack extension disposed uphole of a washdown shoe in a bottom-most well zone. In a top well zone, the outer completion string includes a latch profile, a female inductive coupler, a gravel pack packer, and a sand control assembly and a gravel pack extension disposed downhole of the gravel pack packer. The inner service string includes, among other components, an inner concentric string that is concentrically arranged within a workstring creating an inner-annulus between the workstring and the inner concentric string. The upper completion includes a male inductive coupler that is configured to connect with the female inductive coupler of the outer completion string.