Capillary Injection Valves Prevent Siphoning

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Solution Overview

Problem

In capillary injection systems for wells, siphoning of treatment fluid due to relative vacuum between the capillary tube and wellbore pressure leads to inconsistent fluid flow and potential blockages, making it difficult to regulate and ensure a continuous volume of treatment fluid injection.

Innovation Solution

A bottomhole assembly with a series of injection valves, each with a cumulative set pressure greater than or equal to 6.895 MPa (1 ksi), is deployed to prevent siphoning by maintaining a sufficient pressure differential, ensuring consistent fluid injection and reducing the risk of blockages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the injection pressure or back-pressure at the bottom of the capillary tube is not correct, then the treatment fluid can be injected into the wellbore, but the treatment fluid is siphoned into the wellbore due to hydrostatic pressure being greater than bottom hole pressure

Engineering Contradiction:

Improvecontrol of treatment fluid injectionVSAvoidsiphoning action of treatment fluid

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The injection system is divided into multiple injection valves (first, second, and third injection valves) positioned at different locations along the capillary tube. Each valve independently controls fluid injection at its specific location, allowing segmented pressure management to prevent siphoning while maintaining reliable injection control.

Inventive Principle:

Principle #1Segmentation

2Productivity

If the relative vacuum in the capillary tube causes treatment fluid to boil, then fluid can be injected, but buildup is deposited in the tube leading to blockage

Engineering Contradiction:

Improvetreatment fluid injectionVSAvoidbuildup deposition and blockage

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The injection valves are positioned and pre-configured to maintain positive pressure at critical locations before boiling and deposition can occur. By establishing proper pressure conditions in advance through strategically placed valves, the system prevents the relative vacuum that causes fluid boiling and subsequent buildup deposition.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If voids or bubbles move through the capillary tube, then treatment fluid can flow, but inconsistent application of treatment fluid occurs

Engineering Contradiction:

Improvetreatment fluid flowVSAvoidconsistency of treatment fluid application

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The multiple injection valves create a feedback mechanism where pressure conditions at different locations along the capillary tube are independently monitored and controlled. This allows the system to detect and correct pressure variations that would cause void formation, ensuring consistent treatment fluid application through active pressure management.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP2636840B1Bottomhole assembly for capillary injection system

Publication Date: 2017.02.01 WEATHERFORD TECHNOLOGY HOLDINGS LLC

AI summary

A method of treating production fluid in a wellbore includes deploying a capillary string (60) into the wellbore (5). The capillary string (60) has a plurality of injection valves (100 a-c). The method further includes pumping treatment fluid through the capillary string (60) and into the wellbore (5). The injection valves (100 a-c) have a cumulative set pressure greater than or equal to a hydrostatic pressure of the treatment fluid.