Practical Solutions For Small-Volume Associated Flare and Vent Gas
This paper presents practical solutions to monetize small-volume associated gas and their resulting technoeconomic implications at five offshore locations.
Flaring of associated gas at hydrocarbon production facilities contributes to Scope 1 greenhouse-gas emissions and is a waste of a valuable energy resource. A wide range of technical and technological solutions have been proposed to address this issue. The volumes of flared associated gas, however, are rarely large enough to capture and monetize economically at a single location, hence the struggle to achieve zero routine flaring, especially at offshore locations. This paper presents practical solutions to monetize this small-volume associated gas and their resulting technoeconomic implications at five offshore locations.
A thorough state-of-the-art review has been conducted categorizing external outlooks on process improvement initiatives and technologies that can be applied for flaring and venting management. The study focuses on solutions for offshore facilities where the volume of associated gas is small, 5 MMscf/D or less. Five fields in offshore Malaysia were considered for this purpose. A two-step technoeconomic assessment with a field case study was conducted to firm up internal rate of return (IRR), net present value (NPV), capital expenditures (CAPEX), operational expenditures, variable cost, and revenue for each technology solutions.
The four leading solutions were the following:
- Solution 1—Recovering the flare gas and using it as fuel gas to generate electric power using small-scale generators
- Solution 2—Recovering the flare gas and using it for gas reinjection through existing idle reinjection facilities
- Solution 3—Installing in-situ small-scale gas-to-liquids conversion process
- Solution 4—Improving the efficiency of the existing processing system using data analytics to further reduce or eliminate the gas volumes
Except for the fourth option, additional equipment are required with their respective footprints.
The existing processing system and platform size played a major role in determining the right solution for a given location. For the identified offshore field case studies, vent gas reduction was achieved through Solution 1 at two fields, Solution 2 at one field, and Solution 3 at two fields. The technoeconomics assessment shows that power generation (Solution 1) requires the lowest CAPEX and provides the highest IRR, 21%, with an NPV of $4.2 million. The gas reinjection solution (Solution 2) also has lower CAPEX, but the production increment is not significant and, hence, has the lowest IRR.
There is no single standard or generic solution to help recover associated flare and vent gases and monetize it. Operators need to consider several factors, especially with flare or vent volume variation, low pressure, and limited space at brownfield facilities.