Ether-Modified Methane Gas for Oil Mobilization

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Solution Overview

Problem

Associated gas, primarily composed of methane, is not miscible with oil at pressures below 50 MPa, making it unsuitable for enhanced oil recovery processes in formations with lower pressures, resulting in waste and inefficiency in oil extraction.

Innovation Solution

Injecting a gas formulation comprising at least 70 mol % methane and an ether with 2 to 4 carbon atoms, such as dimethyl ether, into the oil-bearing formation to reduce the minimum miscibility pressure and enhance miscibility with oil, allowing for effective oil mobilization and recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If methane-rich associated gas is injected into the formation, then gas availability is improved, but miscibility with oil deteriorates at pressures below 50 MPa

Engineering Contradiction:

Improvegas availabilityVSAvoidmiscibility with oil

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces ether compounds (2-4 carbon atoms) as intermediary substances that facilitate miscibility between methane-rich associated gas and oil. The ether acts as a mediator that bridges the immiscible phases, enabling the gas to effectively contact and mobilize oil at formation pressures below 50 MPa where pure methane would fail to miscible.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the injection gas by adding ether compounds to the methane-rich associated gas. This parameter change (compositional modification) transforms the gas from a non-miscible state with oil to a miscible state, enabling enhanced oil recovery at lower formation pressures.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If gases with higher carbon numbers (propane, butane) are used for miscible gas injection, then miscibility with oil is improved, but gas cost and complexity increase

Engineering Contradiction:

Improvemiscibility with oilVSAvoidgas formulation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The ether compound serves as a simpler intermediary alternative to using complex higher carbon number hydrocarbons. Instead of injecting propane or butane which require more complex supply chains and handling, the patent uses ether as a mediating substance that achieves the same miscibility effect with simpler logistics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a simpler, more readily available gas formulation (methane-rich associated gas with ether) rather than expensive, specialized higher carbon number gases. This approach uses cheaper, more accessible materials to achieve the desired oil recovery effect.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Object-affected harmful factors

If associated gas is flared to dispose of waste, then safety is maintained, but resource waste increases

Engineering Contradiction:

ImprovesafetyVSAvoidgas waste

Core Design Contradiction:

Object-affected harmful factorsVSLoss of substance

Solution Approach 1:

The patent converts the previously harmful waste product (associated gas that would be flared) into a beneficial resource for oil recovery. By injecting the methane-rich associated gas mixed with ether into the formation, the gas that would have been destroyed by flaring is instead utilized to mobilize and produce additional oil, transforming a waste disposal problem into an economic benefit.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent enables the associated gas to serve a useful function (oil recovery) rather than requiring external disposal infrastructure (flaring systems). The waste gas self-services by being injected into the formation where it performs the dual function of pressure maintenance and oil mobilization when combined with ether.

Inventive Principle:

Principle #25Self-service

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 proposed method enables the recovery of oil from formations with pressures below the minimum miscibility pressure by creating a miscible gas phase, increasing oil sweep efficiency and production, and reducing interfacial tension between oil and connate water, thereby enhancing the overall oil recovery process.

Implementation Method 1

Methodology Applied

Scientific EffectMinimum miscibility pressure reduction:

Implementation Method 2

The injected gas dissolves in the oil forming a single phase solution with the oil, mobilizing the oil by swelling the oil, thereby reducing the viscosity of the oil

Methodology Applied

Scientific EffectOil swelling:

Implementation Method 3

by reducing the interfacial tension between the oil and water in the formation, thereby reducing the capillary forces that hold the oil in place in the formation

Methodology Applied

Scientific EffectInterfacial tension reduction: Surface Tension

Implementation Method 4

The injected gas dissolves in the oil forming a single phase solution with the oil

Methodology Applied

Scientific EffectMiscibility:

Data Source

PatentUS9784081B2Oil recovery process

Publication Date: 2017.10.10 SHELL USA INC

AI summary

The present invention provides a method for enhancing the recovery of oil from a formation. An enhanced oil recovery formulation comprising a gas comprised of a hydrocarbon-containing gas and an ether having from 2 to 4 carbons is injected into an oil-bearing formation to mobilize the oil. The mobilized oil is then produced from the formation.