News Article

Ranking Dehydration & Desalting Technologies

By Pedro Alcalá | Mon, 05/11/2020 - 10:13

Offshore oil and gas production in Mexico depends on onsite processing facilities and equipment. Among the most important tasks that these facilities perform is that of dehydrating and desalting the crude oil that is produced on a daily basis. Associated saltwater highlights crude’s most undesirable characteristic from an infrastructural perspective. Its corrosive properties increase wear and tear on ducts and processing equipment, while limiting an operator’s storage and transportation options. Higher volumes of water in oil can also increase its viscosity, which creates the need to inject more pressure into the system to move the oil through ducts, pipelines and other facilities, which in turn increases operational costs and reduces efficiency and profit margins. As a result, this kind of conditioning is essential. 

In Mexican offshore reservoirs, the presence of water and salt is prominent in the heavy crudes that make up the majority of the country’s daily production. The most immediate and applicable strategy to address this issue is to systematically reduce or shut down production from wells where the presence of water and salt is at its peak. Unfortunately, this strategy is also at odds with the government’s ambitions to increase production. The only option is to be as smart and as efficient as possible when making necessary investments in dehydration and desalting equipment and technologies. These components must guarantee that oil production meets Mexico’s requirements for crude’s entry into the international market. Those requirements are as follows: water content must not exceed 0.5 percent of the crude’s volume and salt content must not exceed 50 PTB (pounds per thousand barrels).  

In this context, Cayros presents a new study in which dehydration and desalting technologies are ranked according to a number of criteria relevant to operators looking for the most economical option. The study begins by identifying and describing down to its scientific and operational requirements six technologies in the following category: three-phase separators, chemical treatments, thermal treatments, gun-barrel separators (also known as wash tanks), mechanical centrifugal separation and electrostatic separators. 

The study ranks these technologies by applying a polling system designed through Cayros’ access to offshore operational data. This system applies one of four ratings (Low, Medium, High and Very High) to the technology based on answers to the following questions: 

How mature is this technology? 

How successful have laboratory tests of this technology proven to be when applied to Mexican crudes?

How successful have tests of this technology proven to be when applied to international crudes? 

How successful have onsite pilot tests of this technology proven to be in offshore facilities? 

What is the quality of the dehydrated and desalted crude that this technology produces? 

How easy is it to handle and dispose of the residual waters that this technology outputs? 

How reliable and available is this technology? 

How large is the unit capacity of this technology? 

How capable is this technology to provide an integrated service?  

How large are the energy requirements of this technology? 

How large are the spatial requirements of this technology? 

How long is the operational life cycle of this technology? 

How long does it take to build and install this technology? 

How big of an investment does this technology represent? 

How difficult and costly is this technology to operate and maintain? 

How much additional infrastructure does this technology require? 

How capable is this technology in terms of chemical injection?

How sensitive is this technology to flow variations? 

After analyzing and weighting the results, the ranking produced a clear winner: from a technical and economic perspective, electrostatic separators proved to be the best option while thermal treatments proved to be the least convenient. It is important to not interpret these results as definitive, but instead as the beginning of a conversation that can implement quantitative data already generated or to be generated in the future and qualitative data such as the experiences of operators in Mexico, which will become much more diversified as PEMEX becomes one among other oil and gas producing entities in the country. These experiences will help contextualize data so that this linear ranking can turn into operational advice, allowing operators to choose the best technology for a specific field and even for a specific well.

Pedro Alcalá Pedro Alcalá Journalist and Industry Analyst