Anchored Riserless Mud Return System for Deepwater Stability

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Solution Overview

Problem

Conventional riserless mud return systems face challenges in deep water and strong currents, where flexible return lines are undesirable due to significant mud losses, environmental concerns, and operational limitations, necessitating a more secure and efficient method for recycling drilling mud during subsea well drilling.

Innovation Solution

A riserless mud return system secured by an anchor to the sea floor, which includes a suction module, a pump, and a return conduit that collects and recycles drilling fluid, preventing mud loss and environmental impact, while anchoring the return line to the sea floor to prevent displacement by currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a flexible return line is used in deep water and strong currents, then the system can be simpler and easier to deploy, but the line may be displaced by currents causing mud losses and operational problems

Engineering Contradiction:

Improveease of deploymentVSAvoidstability of return line position

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The return line system is segmented into a flexible upper portion for ease of deployment and a rigid lower portion anchored to the sea floor for stability. The rigid portion includes a riser and anchor assembly that prevents displacement by currents, while the flexible upper portion maintains operational flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The return line is pre-positioned and anchored to the sea floor before drilling operations begin. The anchor assembly is deployed in advance to secure the rigid portion of the return line, ensuring stability is established before mud circulation starts, preventing current-induced displacement during operations.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If drilling mud is discharged onto the sea floor without recycling, then the system is simpler, but significant mud losses occur and environmental harm is caused

Engineering Contradiction:

Improvesimplicity of mud return systemVSAvoiddrilling mud loss

Core Design Contradiction:

Device complexityVSLoss of substance

Solution Approach 1:

The system establishes continuous circulation of drilling mud by pumping mud down the drill string, collecting it at the sea floor, and returning it to the surface through the rigid return line. This continuous loop prevents mud discharge onto the sea floor and eliminates the need for frequent mud replenishment.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The rigid return line acts as an intermediary conduit between the sea floor suction point and the surface drilling rig. It provides a stable, dedicated pathway for mud return that prevents direct discharge onto the sea floor while maintaining system efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If drilling mud is discharged onto the sea floor, then no recycling equipment is needed, but environmental concerns and visibility problems for ROVs arise

Engineering Contradiction:

Improvenumber of recycling componentsVSAvoidenvironmental impact and ROV visibility

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The continuous mud circulation system captures drilling mud at the sea floor and returns it to the surface, preventing discharge onto the marine environment. This eliminates environmental contamination and maintains clear visibility for ROV operations while establishing a continuous operational loop.

Inventive Principle:

Principle #20Continuity of useful action

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 recycles drilling mud, reducing costs and environmental impact by securely anchoring the return line, preventing mud loss and equipment damage from currents, and enhancing operational reliability in challenging conditions.

Implementation Method 1

a suction module for collecting the drilling fluid emerging from the well bore

Methodology Applied

Scientific EffectSuction: Suction

Implementation Method 2

a pump for receiving the drilling fluid from the suction module and pumping the drilling fluid through the return conduit to a location at the water surface

Methodology Applied

Scientific EffectPumping: Pump

Implementation Method 3

an anchor for securing the return conduit. The anchor is coupled to the return conduit and the sea floor

Methodology Applied

Scientific EffectGravitation: Gravitation

Implementation Method 4

anchoring the return line to the sea floor to prevent displacement by currents

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS7938190B2Anchored riserless mud return systems

Publication Date: 2011.05.10 ENHANCED DRILLING INC

AI summary

A riserless mud recovery system including a mud return line secured by an anchor is disclosed. Some system embodiments for drilling a well bore in an offshore location having a water surface and a subsea formation include an offshore structure positioned on a platform at a water surface, a drill string for forming the well bore suspended from the offshore structure, a drilling fluid source on the platform for supplying drilling fluid through the drill string, a suction module for collecting the drilling fluid emerging from the well bore, a return pipe coupled to the suction module, a pump for receiving the drilling fluid from the suction module and pumping the drilling fluid through the return pipe to a location at the water surface, and an anchor for securing the return pipe, where the anchor is coupled to the return pipe and the subsea formation.