Gas Lift Apparatus with Segmented Strings for Reservoir Protection
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Solution Overview
Problem
Conventional gas lift apparatuses are inadequate for well flushing and snubbing operations, as they allow flushing or killing fluids to enter the reservoir, compromising well recovery time and reservoir integrity.
Innovation Solution
A gas lift apparatus with a tubing production string featuring side pocket mandrels, sliding sleeves, latch seal assemblies, single-bore packers, landing nipples, and flow control devices like tubing-retrievable check valves and plugs, which enable controlled communication and sealing between the tubing and annulus, preventing fluid backflow and ensuring reservoir protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gas lift apparatus is used for well flushing or well killing, then the basic gas lift function is maintained, but flushing fluid or killing fluid will pour into reservoir causing pollution and extending recovery time
Solution Approach 1:
The gas lift apparatus is divided into separate functional sections: an upper string containing gas lift valves and a lower string containing flow control devices (check valves and plugs). This segmentation allows independent control of gas lift injection and fluid flow direction, preventing flushing/killing fluids from entering the reservoir while maintaining gas lift functionality.
Solution Approach 2:
A tubing-retrievable check valve or plug is introduced as an intermediary flow control device in the lower string. This intermediary component acts as a barrier that prevents flushing fluid or killing fluid from reaching the reservoir, while still allowing the gas lift system to function through the upper string.
2Productivity
If conventional gas lift apparatus is used for well flushing, then gas lift production capability is maintained, but recovery time for the oil well becomes longer
Solution Approach 1:
The apparatus employs dynamically controllable flow control devices (tubing-retrievable check valves and plugs) that can be set or retrieved as needed. During flushing operations, these devices are configured to prevent fluid entry into the reservoir, and can be adjusted or removed to facilitate quicker well recovery, thereby reducing overall recovery time while maintaining gas lift production capability.
Solution Approach 2:
The tubing-retrievable check valve or plug can be discarded (left in place) during flushing operations to prevent reservoir contamination, and then recovered (removed) after flushing is complete to accelerate well recovery. This temporary use and subsequent removal of the flow control device optimizes both reservoir protection during flushing and recovery speed afterward.
3Reliability
If conventional gas lift apparatus is used for well killing, then basic well control is achieved, but reservoir pollution occurs
Solution Approach 1:
The apparatus segments the well control function into two separate strings: the upper string handles gas lift injection, while the lower string with retrievable check valves or plugs controls killing fluid flow. This segmentation ensures that killing fluids are contained and directed away from the reservoir, preventing pollution while maintaining effective well control.
Solution Approach 2:
A tubing-retrievable check valve or plug serves as an intermediary barrier in the lower string that specifically prevents killing fluid from reaching the reservoir. This intermediary device enables well killing operations to be performed safely without causing reservoir contamination.
Data Source
AI summary
A gas lift production apparatus is provided for use in flushing and snubbing well operation. The apparatus comprises upper production string and lower production string. The upper production string includes at least one side pocket mandrel carrying a gas lift valve, tubular strings connected with every side pocket mandrel, a sliding sleeve installed as part of the production string below side pocket mandrels and a latch seal assembly threaded in the tubular string below the sliding sleeve. The lower production string includes a single bore packer below the latch seal assembly, tubular strings, a landing nipple and a bell mouth at the bottom of the production string. The upper production string are run in and removed as a single unit from the packer which is anchored within the well casing. It is emphasized that this apparatus is provided with three functions such as producing a gas lift well, flushing well and snubbing well operation. Application of the apparatus will prevent flushing or killing fluid from polluting the reservoir and increase production efficiency.