Staged Underreamer Cutter Block for Wellbore Enlargement

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Solution Overview

Problem

In oil and gas well drilling, existing methods for enlarging the wellbore below existing casing strings are limited, reducing the annular space for cementing and the production flow area, which restricts the use of larger casing diameters and affects oil and gas production.

Innovation Solution

A cutting apparatus with expandable cutter arms and stabilizer portions that transition between retracted and expanded positions, allowing for staged reaming and stabilization within the wellbore, enabling efficient enlargement of the wellbore diameter and maintaining structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If conventional underreamers with single-stage cutter blocks are used, then the tool structure is simple, but the wellbore enlargement is limited and annular space for cementing is insufficient

Engineering Contradiction:

Improveannular space for cementingVSAvoidcutter block structure

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The cutter block is divided into multiple stages with different cutter arm configurations. The first stage has cutter arms extending to a first radial position for initial reaming, while the second stage has cutter arms extending to a second radial position for further enlargement. This segmentation allows progressive wellbore enlargement to create sufficient annular space for cementing while maintaining manageable structural complexity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cutter arms are designed to be movable between different radial positions, transitioning from a retracted state for passage through existing casing to an extended state for wellbore enlargement. This dynamic configuration enables the tool to adapt its cutting radius based on operational requirements, maximizing annular space creation while controlling device complexity through controlled movement mechanisms.

Inventive Principle:

Principle #15Dynamics

2Productivity

If larger diameter casing strings are used, then production flow area increases, but the annular space for cementing operation is reduced

Engineering Contradiction:

Improveproduction flow areaVSAvoidannular space for cementing

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

The underreamer performs preliminary wellbore enlargement below the existing casing strings before the larger diameter casing strings are installed. By pre-reaming the wellbore to a larger diameter, sufficient annular space is created in advance to accommodate the cementing operation for the larger casing strings, thereby enabling increased production flow area without compromising cementing capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The solution addresses the dimensional conflict by operating in a different spatial dimension - creating the enlarged wellbore diameter in the radial dimension before installing the larger casing. This sequential dimensional change allows the annular space to be established at the required size to accommodate both the larger casing and adequate cementing area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If cutter arms are extended to maximize wellbore enlargement, then reaming effectiveness increases, but tool stability decreases

Engineering Contradiction:

Improvereaming effectivenessVSAvoidtool stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The cutter block is segmented into multiple stages with stabilizer portions positioned between cutter arms of different stages. These stabilizer portions engage with the wellbore wall to provide rotational and positional stability during operation, preventing tool wander and maintaining cutting accuracy. This segmentation with integrated stabilizers allows extended cutter arms for effective reaming while maintaining tool stability through the stabilizing action of the intermediate portions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Stabilizer portions are introduced as intermediary elements between the cutter arms and the tool body. These stabilizer portions act as mediators that transfer stability requirements from the tool body to the cutter assembly, providing rotational support and positional control to extended cutter arms during wellbore enlargement operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11814903B2Staged underreamer cutter block

Publication Date: 2023.11.14 SCHLUMBERGER TECH CORP

AI summary

A downhole assembly includes a bit and a cutting tool uphole of the bit. The cutting tool has one or more expandable cutter arms. The one or more expandable cutter arms include at least one stabilizer portion having a radial position that is about the same as a gauge of the bit when the one or more expandable cutter arms are in an expanded position. A spline on the cutter arms are used by a cutting tool to move the cutter arms.