Subterranean Cavern for Downhole Gravity Separation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current methods for producing oil from subterranean zones often result in oil being lifted with other formation fluids like water, necessitating costly surface treatment to separate the two.

Innovation Solution

The method involves forming a subterranean cavern within a wellbore by spraying acid onto the inner wall, allowing hydrocarbons and water to separate by gravity, and then pumping the oil from the cavern to the surface while minimizing water and other fluids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If artificial lifting mechanisms (electrical submersible pumps, gas lifts) are used to add energy to the fluid column, then the amount of oil produced from the subterranean zone increases, but the oil is lifted with other formation fluids (water) requiring costly surface treatment

Engineering Contradiction:

Improveamount of oil producedVSAvoidwater and formation fluids mixed with oil

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The wellbore is segmented into two distinct functional zones: a lower production zone where hydrocarbons are collected in a cavern, and an upper separation zone where the mixture separates by density. This vertical segmentation allows oil to be produced while water and formation fluids remain below, eliminating the need for surface treatment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from horizontal fluid transport in a conventional wellbore to vertical three-dimensional separation. By creating a cavern that extends vertically and allowing gravity-driven separation in the third dimension, the system achieves oil-water separation without requiring surface treatment facilities.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of substance

If a subterranean cavern is formed within the wellbore to enable gravity separation, then water and formation fluids are separated from oil, but the wellbore structure must be modified (acid spraying to expand radius)

Engineering Contradiction:

Improveseparation of water and formation fluids from oilVSAvoidmodification of wellbore structure

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The wellbore radius is changed from its original smaller dimension to a larger dimension by acid etching. This parameter change creates the necessary volume for gravity separation while maintaining a relatively simple wellbore structure. The acid spraying process modifies the wellbore geometry to achieve the desired cavern volume.

Inventive Principle:

Principle #35Parameter changes

3Volume of stationary object

If acid is sprayed onto the inner wall of the wellbore to form a larger radius cavern, then the cavern volume increases for better separation, but the wellbore structure is chemically modified

Engineering Contradiction:

Improvecavern volumeVSAvoidchemical modification of wellbore structure

Core Design Contradiction:

Volume of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The acid spraying process, which could be considered harmful to the wellbore structure, is converted into a beneficial tool for creating the separation cavern. The acid etching intentionally modifies the wellbore geometry to expand the radius and create volume for gravity separation, transforming a potentially damaging process into a constructive one.

Inventive Principle:

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

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 enhances downhole gravity separation, increases oil inflow, reduces the need for surface water treatment, and can store or dispose of carbon dioxide and water, thereby lowering production costs and time.

Implementation Method 1

spraying acid onto an inner wall of a wellbore to form a subterranean cavern

Methodology Applied

Scientific EffectAcid etching: Chemical Bonding

Implementation Method 2

The liquid hydrocarbons and the water separate under gravity within the subterranean cavern

Methodology Applied

Scientific EffectGravity separation: Gravitation

Implementation Method 3

drawing the liquid hydrocarbons from the subterranean cavern to a surface of the wellbore

Methodology Applied

Scientific EffectPumping: Pump

Data Source

PatentUS11187044B2Production cavern

Publication Date: 2021.11.30 SAUDI ARABIAN OIL CO

AI summary

A method includes spraying acid onto an inner wall of a wellbore formed in a subterranean zone with entrapped hydrocarbons that flow into the subterranean zone. Spraying the acid forms a subterranean cavern within a portion of the wellbore, the subterranean cavern being wider than the wellbore. The entrapped hydrocarbons flow into the subterranean cavern. The entrapped hydrocarbons include liquid hydrocarbons and water. The liquid hydrocarbons and the water separate under gravity within the subterranean cavern. The method also includes drawing the liquid hydrocarbons from the subterranean cavern to a surface of the wellbore.