Toe-Dominant Solvent Injection to Prevent ESP Gas Locking
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Solution Overview
Problem
Gas interference with electric submersible pumps (ESPs) during solvent or non-condensable gas injection in steam-assisted gravity drainage (SAGD) processes leads to reduced oil production rates and increased steam-to-oil ratios, necessitating methods to minimize gas interference without increasing costs or completion complexity.
Innovation Solution
Implementing a well-pair with dual or triple injection tubings, preferentially injecting more solvent into the toe than the heel, and adjusting solvent distribution based on gas lock frequency to mitigate gas interference, thereby optimizing oil production rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solvent is injected into the reservoir during SAGD process, then oil viscosity is reduced and production is enhanced, but gas interference with ESP occurs and pump efficiency decreases
Solution Approach 1:
The injection well is divided into multiple injection zones (heel and toe regions) with separate injection strings. This segmentation allows independent control of solvent injection at different locations, enabling preferential injection at the toe region to direct solvent away from the ESP and minimize gas interference while maintaining production enhancement benefits
Solution Approach 2:
Different injection strategies are applied to different regions of the well. The toe region receives preferential solvent injection to create a solvent-rich zone that directs flow away from the ESP, while the heel region receives reduced or no solvent injection. This local differentiation optimizes both production enhancement and pump protection
2Productivity
If more steam is injected to mobilize heavy oil, then oil recovery is improved, but steam-to-oil ratio increases and energy consumption rises
Solution Approach 1:
The invention changes the physical state parameter of the injection fluid from steam to solvent (or reduced steam). By injecting solvent at reservoir conditions or slightly elevated temperatures, the process achieves oil mobilization without requiring large amounts of steam, thereby reducing the steam-to-oil ratio and associated energy consumption while maintaining or improving recovery
3Productivity
If dual or triple injection tubings are implemented, then solvent distribution is optimized and gas interference is minimized, but well completion complexity increases
Solution Approach 1:
The injection system is segmented into multiple independent injection strings (heel and toe) that can be controlled separately. This segmentation enables optimized solvent distribution to different reservoir zones, directing solvent preferentially to the toe region to minimize gas interference with the ESP while maintaining manageable completion complexity through modular design
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
Enhances oil production rates by minimizing gas interference at the ESP, reducing the steam-to-oil ratio, and maintaining efficient solvent distribution within the reservoir.
Implementation Method 1
injecting more solvent into the toe-injection tube than into the heel-injection tube, thereby minimizing gas interference with the ESP
Implementation Method 2
injecting more solvent into the toe-injection tube than into the heel-injection tube
Data Source
AI summary
A method for producing heavy oil using solvent injection without gas interference at the electric submersible pump (ESP), the method including completing the injection well with two or more injector tubings, at a heel and toe, and optionally therebetween. Ideally, when gas locking of the ESP is detected, the operator switches to toe dominant injections, mitigating the gas locking problem, and producing oil at a faster rate than possible with evenly distributed injections.