The MEG (Mono Ethylene) Injection Gas Dehydration Process Evaluation for the Margarita Field Development

摘要

The objective of the study is to select the gas dehydration process system within the Margarita Field Development Project based on “MEG (MONO ETHYLENE) Injection with Mechanical Refrigeration” and compare it with the “Glycol Dehydration Process System”, from the technological and economical point of view. The dehydration process based on TEG is the most common process for natural gas dehydration; it is an efficient technology and its operation is very well known. In order to reduce the CAPEX and OPEX of the Project, the operator has studied potential process options. One way to optimize the gas dehydration process is by simplifying and combining it with other processes, which is the case when considering the combined MEG injection with mechanical refrigeration, a common practice in the Industry. The scope of this report covers: o Estimate of the downstream and utility equipments as required (glycol loss, glycol rate recirculation, electrical requirements, etc) o Cost Estimate (OPEX / CAPEX). O Explanation of uncertainties and risks that may be associated in applying the dehydration process on this particular application, and steps (if required) to eliminate those uncertainties. O To take experience of similar plants with similar requirement. The MEG Injection together with a Dew Point Plant is able to dehydrate the natural gas, because the chiller unit operates at low temperatures and it permits the water content of the gas to be condensed and removed in "cold separation", but this process requires inhibitor injection in order to avoid hydration formation, being glycol the usual inhibitor. Removing the Contactor Tower and changing TEG by MEG has little impact in the Dew Point Plant design. The additional power required in the propane compressor is compensated in the glycol pump which is lower power consumption because the MEG injection rate is lower than the TEG one. The different aspects evaluated between MEG Injection and Contactor Tower with TEG, are favorable toward the MEG Injection as: o CAPEX: FOB Cost. O MEG Injection saves MEG regeneration unit which is smaller and lighter. O Elimination of TEG contactors will simplify the plant, reduce installation cost and avoid large heavy vessels with transportation constraints. O MEG injection is easier to regenerate than TEG and alleviates environmental issues with BTEX emission. After taking in consideration all the points in favor of the MEG Injection, it is recommended to install it in the Gas Treatment Plant.