Resource Efficient Central Gas Processing Facility with Reduced Methanol Demand
Authors: Elizareva N. L. , Kolchin A. V. , Kurochkin A. V. 
Published: October 2015

Low temperature separation technology is commonly used for field gas processing. Nevertheless typical technological schemes ensure high-quality gas treatment for further transportation with a significant pressure drop at the facility only the first 10-12 years of field production.

Other problems are a sizeable amount of low head flash gases and methanol entrainment with commercial products that increase the operating costs.

Research objective is a design resource and energy saving technology of gas and gas condensate treatment that is characterized by high operation effectiveness, decrease in amount of flash gases and methanol consumption.

As a base was chosen a technological scheme that includes inlet separation, recuperative cooling, flash condensation of gas, reducing, low temperature separation, methanol feed points at interstage and low temperature separation. Processed gas heats by feed gas and outputs from the facility. Obtained condensates intermix and then stabilize. Flash gases burn on flare.

Developed technology assumes substitution of recuperative cooling and flash condensation at interstage separation by gas refluxing due to obligue cooling with low temperature gas and condensate. To decrease methanol consumption when ensuring non-hydrate operation of refluxing and low temperature separation processes low temperature separation condensate injection is provided into the refluxer for methanol stripping by feed gas.

Simulation was realized in software package HYSYS.

Developed technology allows exceeding compressionless operating period of a field due to decrease in minimum allowed gas pressure down to 4,7 MPa that at 0,9 MPa lower than the same parameter of basic scheme.

Such gas treatment allows increasing an output of a commercial gas and a gas condensate for 2-3 %. Notably that the amount of flash gases decreases for 20% in comparison with basic scheme when operating in a regime that ensures standardized quality of commercial products.

Developed technology increases mass output of stabilized gas condensate for 7,3% as well as recovery ratio of C3+ components for 14% in comparison with basic scheme when the developed technology operates in a regime of maximum hydrocarbon component recovery.

Methanol stripping from the low temperature condensate in the refluxer allows decreasing inhibitor consumption for 10-12% in comparison with the basic scheme due to recycle of the major part of entrainment inhibitor. Location of a feed point depends on gas treatment conditions.

It is recommended to operate developed technology at minimum pressure drop on reduction valve as the output of commercial gas and condensate increases for 2-3% as well as the amount of flash gases decrease for 5,3%.

Developed technology allows significant flexibility in operation regimes depending on requirements to quality of the commercial products. It might be consider as a component of a complex solution in efficiency improve of gas field production.

Developed technological scheme is applicable during the processing of well streams from gas and gas condensate fields. The main technical solutions protected by a patents of RF.