Pressure Chamber System for Maintaining ECD During Drill String Connections

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Solution Overview

Problem

The drilling industry faces challenges with maintaining a constant equivalent circulation density (ECD) during drilling operations, particularly when coupling or disconnecting new lengths of drill string, leading to unpredictable and unstable pressure conditions that can result in poor hole stability and formation fracturing.

Innovation Solution

A method involving a pressure chamber system with upper and lower chambers separated by an intermediate valve, where the drill string is locked and sealed, allowing for controlled pressure maintenance and fluid circulation, enabling consistent ECD by managing pressure transitions during drill string connections and disconnections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the drill string is stopped for coupling or disconnection, then the drill string can be modified, but the pressure on the formation drops and ECD becomes unstable

Engineering Contradiction:

ImproveAbility to couple or disconnect drill stringVSAvoidStability of ECD and pressure on formation

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The device segments the drill string into two separate parts that can be independently handled. The lower part remains in the well with maintained pressure and circulation, while the upper part is disconnected and replaced. This segmentation allows drill string modification without stopping circulation in the wellbore, thereby maintaining stable ECD.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The device nests a hollow body containing the lower drill string part within the upper drill string part during the coupling process. The hollow body acts as a temporary containment structure that maintains pressure and circulation while allowing the upper part to be disconnected and replaced, enabling seamless transitions without pressure loss.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If drilling fluid pressure is increased to prevent formation fluid inflow, then well control is improved, but formation fracturing risk increases

Engineering Contradiction:

ImproveWell control capabilityVSAvoidFormation fracturing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The device enables continuous circulation of drilling fluid through the lower drill string part even during coupling operations. This continuous circulation maintains stable hydrostatic pressure on the formation, preventing both formation fluid inflow and formation fracturing by avoiding pressure fluctuations that would otherwise occur during drill string modifications.

Inventive Principle:

Principle #20Continuity of useful action

3Ease of operation

If drilling fluid circulation is stopped during drill string coupling, then the coupling operation can be performed, but hole stability deteriorates and formation fracturing may occur

Engineering Contradiction:

ImproveAbility to perform coupling operationVSAvoidHole stability and formation integrity

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The device extracts the lower drill string part into a hollow body that is sealed and pressurized, separating it from the coupling operation. This allows the upper part to be disconnected and replaced while the lower part maintains continuous circulation and pressure, thereby maintaining hole stability and preventing formation fracturing during the coupling operation.

Inventive Principle:

Principle #2Taking out (Extraction)

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

This approach ensures a stable and predictable ECD, facilitating the drilling of difficult formations by maintaining consistent pressure and fluid flow, even during drill string modifications, thereby enhancing drilling efficiency and stability.

Implementation Method 1

the intermediate valve is closed, which separates the upper and lower pressure chambers, to maintain pressure in the lower chamber and to balance the pressure in the upper chamber to that of the surroundings

Methodology Applied

Scientific EffectPressure balance: Pascal's Law

Implementation Method 2

seals which prevent leakage of drilling fluid at the interfaces between the body and the drill string parts

Methodology Applied

Scientific EffectSealing:

Implementation Method 3

locking anchors for securing the drill string parts in the upper and lower chambers

Methodology Applied

Scientific EffectMechanical locking: Mechanical Fastener

Data Source

PatentEP2171207B1Device and method for maintaining constant pressure on, and flow drill fluid, in a drill string

Publication Date: 2016.08.24 SIEM WIS

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AI summary

A device is described for maintaining a predominately constant pressure on, and flow of drilling fluid in, a drill string (100) where drilling fluid is supplied via a circulation system for drilling fluid. The device comprises a mainly elongated, internally hollow body (10) arranged to surround the drill string where the hollow body (10) comprises at least an upper pressure chamber (40a) and a lower pressure chamber (40b) connected with respective inlet and/or outlet (50a, 50b) for drilling fluid from or to the drilling fluid circulation system, as said pressure chambers (40a, 40b) are able to be closed and separated by an intermediate valve (70) arranged for circulation of drilling fluid into or out of the drill string (100) during coupling up or disconnecting of a new length of drill string (100). A method to maintain the mainly constant pressure of drilling fluid in a drill string is also described.