Investigation of Causes of Tight Emulsions in Gas Oil Separation Plants

Abstract Sludge formation could significantly impair well productivity if deposited in the wellbore or surface flow lines. In a field where sludge formation is not common, an oil production well showed a sudden deterioration in well productivity. Thorough investigation of abnormal well performance, from surface and sub-surface perspective, indicated that the deposition of a thick layer of a tight emulsion across the surface choke has resulted in ceasing the oil flow to the gas oil separation plant. Extensive lab analysis indicated that the obstruction material was a sludge deposition promoted by the presence of asphaltene, high amount of iron and low pH brine. It is noteworthy to mention that the analytical results of lab prepared emulsion samples elucidate the rule of low pH aqueous solution, asphaltene and iron ions in inducing tight emulsion formation which helps to understand the root causes of sludge deposition. To come up with a cost-effective remedial treatment considering health, safety and environment (HSE), different emulsion breaking formulations, including different de-emulsifiers and anti-sludge agents, were examined in this study. An effective diesel-based formulation including proper de-emulsifier and anti-sludging agent was used during the execution of the field job. The design of the field job took into consideration a minimal footprint to the environment through the flowback of the well to the neighboring gas oil separation plant. This paper summarizes the joint efforts by production engineers and lab scientists to systemically tackle such major flow assurance issues which could significantly jeopardize wells productivity. The systemic approach starts with problem detection through well intervention and sample collection. It also includes the lab work which was carried out to identify the type and composition of deposition and evaluate/optimize a proper formulation for sludge deposition removal. The paper discusses in detail the design and execution of a successful field treatment, which has resulted in restoring and maintaining the well potential.

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Troubleshooting Gas Dehydration Systems Using Data Analysis

10.2118/207390-ms ◽

2021 ◽

Author(s):

Abdullah Al-Aiderous

Keyword(s):

Data Analysis ◽

Operating Temperature ◽

Triethylene Glycol ◽

Gas Oil ◽

Separation Plant ◽

Oil Separation ◽

Analysis Techniques ◽

Using Data ◽

Product Specifications

Abstract The objective of this paper is to showcase the successful and innovative troubleshooting data analysis techniques to operate a TEG dehydration system optimally and reduce glycol loss and to meet the product specifications in one of the gas dehydration systems in an upstream gas oil separation plant (GOSP). The gas dehydration system using Triethylene Glycol (TEG) is the most widely used and reliable gas dehydration system in upstream operation. These proven data analysis techniques were used to tackle major and chronic issues associated with gas dehydration system operation that lead to excessive glycol losses, glycol degradation, and off-specification products. Glycol loss is the most important operating problem in the gas dehydration system and it represents a concern to the operation personnel. Most dehydration units are designed for a loss of less than 1 pound of glycol per million standard cubic feet of natural gas treated, depending on the TEG contactor operating temperature. In this paper, comprehensive data analysis of the potential root causes that aggravate undesired glycol losses degradation and off-specification products will be discussed along with solutions to minimize the expected impact. For example, operating the absorption vessel (contactor) or still column at high temperature will increase the glycol loss by vaporization. Also, the glycol losses occurring in the glycol regenerator section are usually caused by excessive reboiler temperature, which causes vaporization or thermal decomposition of glycol (TEG). In addition, excessive top temperature in the still column allows vaporized glycol to escape from the still column with the water vapor. Excessive contactor operating temperature could be the result of malfunction glycol cooler or high TEG flow rate. This paper will focus on a detailed case study in one of the running TEG systems at a gas-oil separation plant.

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