Well Control Sub for Chemical Injection and ICV Switching
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Solution Overview
Problem
Existing chemical injection systems in oil and gas wells face issues with chemical evaporation and clogging due to void formation in capillary tubes, leading to reduced well performance and inaccurate flowrate monitoring, especially when annulus pressure drops below hydrostatic pressure.
Innovation Solution
A well system with a tubular and control system that includes a directional valve and inflow control valve (ICV), allowing selective routing of operating fluids to injection ports or isolating fluid flow, and utilizing a surface-controlled actuator to manage chemical injection and valve positioning, with optional pressure sensors for diagnostic and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical injection is performed through a capillary tube, then chemical additives can be injected into the well, but chemical evaporation and clogging occur when annulus pressure drops below hydrostatic pressure
Solution Approach 1:
The patent introduces a check valve as an intermediary component in the chemical injection system. This check valve acts as a mediator that prevents backflow and maintains positive pressure in the capillary tube, thereby eliminating the harmful effects of chemical evaporation and clogging while preserving the chemical injection function
Solution Approach 2:
The patent applies beforehand cushioning by pre-positioning a check valve in the chemical injection line to prevent pressure drops before they can cause harmful effects. The check valve is installed in advance to cushion against potential backflow and maintain continuous positive pressure, preventing chemical evaporation and particulate formation before they can occur
2Object-generated harmful factors
If check valves are installed on capillary tube exits, then backflow is prevented, but they cannot maintain fluid column when annulus pressure drops below hydrostatic pressure
Solution Approach 1:
The patent applies parameter changes by selecting a check valve design with specific pressure characteristics that can maintain the fluid column under varying annulus pressures. The check valve is chosen or designed to operate effectively across the expected pressure range, changing its flow characteristics to maintain reliability when annulus pressure drops below hydrostatic pressure
3Quantity of substance
If relief valves are used to maintain chemical level, then chemical level can be maintained, but injection pump head requirements increase and leakage occurs over time
Solution Approach 1:
The patent extracts the problematic relief valve component from the chemical injection system and replaces it with a check valve configuration. This removal eliminates the energy losses and leakage issues associated with relief valves while maintaining the essential function of chemical level control through a simpler valve mechanism
4Loss of substance
If chemical additives are injected at low flowrates, then cost is reduced, but accurate flowrate monitoring becomes difficult
Solution Approach 1:
The patent replaces mechanical flowrate monitoring methods with electronic or digital measurement systems that can accurately measure low flowrates. This substitution enables precise monitoring of chemical additive flowrates even at the low rates needed for cost-effective injection, eliminating the trade-off between cost and measurement accuracy
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
The system effectively maintains chemical levels in the capillary tube, preventing evaporation and clogging, enabling accurate flowrate monitoring and enhancing well performance by ensuring consistent chemical injection and valve operation.
Implementation Method 1
a control system selectively changeable to a position in which operating fluid is routed to an injection port in the tubular and is selectively changeable to another position in which operating fluid is routed to a valve
Implementation Method 2
surface controlled actuator connected to the directional valve
Implementation Method 3
surface controlled actuator connected to the directional valve
Implementation Method 4
a pressure sensor in communication with the fluid line for use in one of diagnostic, verification, or positioning requirements
Data Source
AI summary
A production string is installed in a well that includes production tubing and a control sub. In the control sub is a control system that controls both operation of an inflow control valve (“ICV”) in the production string and chemical injection into the production string. The chemical injection is provided from surface through injection tubing installed in the well, which connects to a directional valve included with the control system. Positioning the directional valve diverts chemical injection to reposition the ICV between an open and closed configuration, or injects the chemical injection into the production string. A surface controlled actuator is used to operate the directional valve.