Interface Rag Treatment via Thermal Decomposition and Diluent Mixing
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Solution Overview
Problem
The existing methods for treating the 'rag' mixture accumulating at the oil/water interface in crude oil production are inefficient, requiring external processing that is costly and time-consuming, and result in undesirable constituents being left in the dilbit, leading to penalties from refineries.
Innovation Solution
A method involving controlled removal of rag from upstream separators, heating to 350°F to decompose additives, mixing with additional diluent to achieve 30 API gravity, and processing through an electrostatic treater or hydrocyclone cluster to separate solids and water, eliminating the need for tank storage and flash treaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tank processing is used to separate rag by gravity, then separation effectiveness is improved, but processing time and cost increase significantly
Solution Approach 1:
The invention changes the temperature parameter by heating the rag mixture to 250-300°F, which fundamentally alters the separation mechanism from gravity-based (tank processing) to thermal decomposition and flash evaporation-based. This parameter change enables rapid separation within minutes rather than days, resolving the time-effectiveness contradiction.
Solution Approach 2:
The invention utilizes phase transitions through flash evaporation of water and light hydrocarbons at elevated temperatures. The rapid phase change from liquid to vapor enables instantaneous separation of water, light hydrocarbons, and solids from the rag mixture, eliminating the need for prolonged gravity separation in large tanks.
2Productivity
If flash treating is used to remove water from rag, then processing speed is improved, but undesirable constituents (solids, asphaltenes, salts) remain in the dilbit
Solution Approach 1:
The invention optimizes temperature parameters (250-300°F) and residence time parameters to achieve complete thermal decomposition of chemicals and effective separation of all undesirable constituents. This parameter optimization ensures that unlike conventional flash treating, the process removes solids, asphaltenes, and salts while maintaining high processing speed.
Solution Approach 2:
The invention implements continuous heating and continuous separation action throughout the process. The rag mixture undergoes continuous thermal decomposition and phase separation in a controlled environment, ensuring complete removal of harmful constituents without the interruptions or incomplete separation associated with conventional batch flash treating.
3Manufacturing precision
If external processing is used for rag, then separation capability is improved, but operational complexity and cost increase
Solution Approach 1:
The invention enables the separation process to occur within the existing dehydration and desalting equipment itself, utilizing the equipment's own heating and separation capabilities. The process self-regulates through controlled temperature increase and automatic phase separation, eliminating the need for complex external processing systems and reducing operational complexity.
Solution Approach 2:
The invention merges the rag treatment process with the existing dehydration and desalting operations. By combining heating, thermal decomposition, and separation functions into a single integrated process flow within existing equipment, the system eliminates separate external processing steps and reduces overall operational complexity.
4Manufacturing precision
If heat is added to control rag volume, then rag separation is improved, but energy consumption increases
Solution Approach 1:
The invention utilizes phase transitions (liquid to vapor) that occur at relatively low temperature differences (250-300°F). The rapid phase change of water and light hydrocarbons provides efficient separation with minimal energy input compared to alternative heating methods, as the phase transition itself drives the separation mechanism rather than requiring excessive temperature increase.
Data Source
AI summary
A method for treating an interface rag includes the steps of removing a volume of rag at a controlled rate from an upstream rag source and passing the rag through a high pressure pump and a heater. The heater heats the rag to a temperature of at least 350° F. to thermally decomposing any chemicals that had been added to the interface rag to promote separation. Diluent is then mixed with the heated rag to cool the rag to a temperature less than 300° F. and produce a 30 API rag. The cooled diluted rag is then treated in an electrostatic treater or sent directly to a hydrocyclone cluster. The electrostatic treater is preferably a vertical electrostatic treater with a conical-shaped lower portion and a means for agitating the solid-laden water within the treater to prevent the solids from settling on the bottom of the treater.