Solvent Mixture for Downhole Sulfur Removal and Formation Stimulation
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Solution Overview
Problem
Elemental sulfur deposition in production wells and gathering facilities is a challenge for sour gas reservoirs, causing flow restrictions and operational issues due to the solubility of sulfur in sour gas, and existing solvents like diaryl disulfide and dimethyl disulfide have limitations such as odor issues and availability problems, while also requiring careful consideration to maintain formation permeability.
Innovation Solution
A solvent mixture comprising an elemental sulfur solvent fraction, primarily dimethyl disulfide, and an odorant fraction with lactate ester solvents like ethyl lactate, which generates lactic acid in situ to dissolve sulfur deposits and stimulate the formation without adversely affecting permeability, reducing odor intensity through the 'white smell effect'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMDS-based solvents are used to dissolve elemental sulfur, then sulfur removal effectiveness is improved, but odor intensity increases making the solvent impractical or impermissible to apply
Solution Approach 1:
The patent combines DMDS (effective sulfur solvent) with lactate ester solvents and other components to create a composite solvent mixture. This composite formulation maintains the sulfur-dissolving capability of DMDS while the lactate esters and other ingredients mask the unpleasant odor, making the solvent practical for field application.
Solution Approach 2:
The lactate ester solvents act as intermediary substances that interact with the DMDS to reduce its odor impact. These intermediaries preserve the primary function of sulfur removal while modifying the sensory characteristics to acceptable levels.
2Reliability
If solvents are used to dissolve elemental sulfur downhole, then sulfur deposition is reduced, but formation permeability may be adversely affected
Solution Approach 1:
The patent carefully selects and adjusts the chemical parameters of the solvent mixture, including the type and concentration of disulfide compounds, lactate esters, and other ingredients. By optimizing these parameters, the solvent achieves effective sulfur dissolution while maintaining compatibility with formation rock and preserving permeability.
Solution Approach 2:
The solvent mixture is formulated to have different functional components that perform localized functions: DMDS targets sulfur dissolution, lactate esters provide odor control and potential formation stimulation, and other ingredients address specific downhole conditions. This localized functionality ensures effective sulfur removal without harmful effects on formation permeability.
3Object-affected harmful factors
If DADS-based solvents are used to remove elemental sulfur, then sulfur removal effectiveness and odor acceptability are improved, but availability and ease of utilization deteriorate
Solution Approach 1:
The patent employs DMDS and other readily available, cost-effective solvent ingredients that can be easily manufactured and supplied. While individual components may have shorter stability periods, the overall formulation achieves effective sulfur removal and acceptable odor characteristics without relying on scarce or expensive specialty chemicals like DADS.
Solution Approach 2:
The patent optimizes the concentration ratios and chemical parameters of available ingredients to achieve performance comparable to or better than DADS-based solvents. By adjusting formulation parameters, the patent makes effective sulfur removal achievable with readily obtainable materials.
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
Effectively removes elemental sulfur from well components, maintains or improves formation permeability, and reduces odor intensity, enabling continuous operation and enhanced hydrocarbon production.
Implementation Method 1
the elemental sulfur solvent fraction of the solvent mixture dissolves elemental sulfur deposited on well components
Implementation Method 2
contacting the solvent mixture with water such that the lactate ester solvent within the odorant fraction reacts with the water to generate lactic acid
Data Source
AI summary
Solvent mixtures for downhole elemental sulfur removal and formation stimulation, and methods for utilizing such solvent mixtures, are described herein. One method includes providing a solvent mixture that includes an elemental sulfur solvent fraction and an odorant fraction that includes a lactate ester solvent. The method also includes injecting the solvent mixture into a hydrocarbon well such that the elemental sulfur solvent fraction of the solvent mixture dissolves elemental sulfur deposited on well components, and contacting the solvent mixture with water such that the lactate ester solvent within the odorant fraction reacts with the water to generate lactic acid. The method further includes stimulating a formation through which the hydrocarbon well extends by flowing the solvent mixture including the lactic acid through the hydrocarbon well and into the formation.