Abstract Recent developments in environmental regulations have made emissions of the aromatic compounds Benzene, Toluene, Ethyl-Benzene, and Xylene isomers (BTEX) and other Volatile Organic Compounds (VOCs) from glycol units a major concern for the natural gas industry. Hence, quantifying the absorption levels has become more important in recent years due to increased restrictions on BTEX/VOC Emissions from glycol dehydration units.
This problem is one, which requires careful attention in the design phase, and also the environmental considerations as mentioned above are increasingly driving the selection and operation of process alternatives to reduce the BTEX/VOCs emissions in the atmosphere.
In this paper, we will focus the study on one of the glycol dehydration unit for one of the onshore petroleum fields at Abu Dhabi managed by ADCO. Firstly, we quantify the BTEX/VOCs emission levels vented out to atmosphere, along with a description of the sampling technique used. Secondly, we optimize the process parameters around all major equipments in the glycol unit, i.e. absorber, flash tank, and regenerator. The optimization study will start by building a process simulation model which is based on actual design data given by the glycol unit vendor and verified by operational data.
1. Introduction Abu Dhabi Company for Onshore Oil Operations (ADCO) operates a recently commissioned onshore oil/gas facility located in Abu Dhabi. The primary objective of this facility is to separate oil, gas, and water produced from the field. Oil separated from the mixture in the three-phase separator is pumped to facilities at another field for further processing before oil shipment. The gas is dehydrated and re-compressed then re-injected back into the reservoir to maintain the reservoir pressure. The water is further processed in a water treatment plant before disposal.
1.1 Process Description The process flow diagram for the Central Degassing Station (CDS) for this field is shown in Fig. 1. The crude coming from the existing and new wells is gathered in manifolds located at the Remote Degassing Station (RDS) at about 5 Km from the Central Degassing Station (CDS).
A test separator is present at both stations. The crude collected at RDS-1 is routed via a new 16" transfer line to the inlet manifold of the CDS. At the CDS the oil, gas, and water are separated in one of the two 3-phase production separators.
The oil separated at the CDS is pumped by booster and Main Oil Line (MOL) pumps to another ADCO field, through the existing 12" MOL for final separation and salt control, in which the oil is washed with fresh water to reduce the salt level.
1.1 Process Description The process flow diagram for the Central Degassing Station (CDS) for this field is shown in Fig. 1. The crude coming from the existing and new wells is gathered in manifolds located at the Remote Degassing Station (RDS) at about 5 Km from the Central Degassing Station (CDS).
A test separator is present at both stations. The crude collected at RDS-1 is routed via a new 16" transfer line to the inlet manifold of the CDS. At the CDS the oil, gas, and water are separated in one of the two 3-phase production separators.
The oil separated at the CDS is pumped by booster and Main Oil Line (MOL) pumps to another ADCO field, through the existing 12" MOL for final separation and salt control, in which the oil is washed with fresh water to reduce the salt level.