The current trend of the oil and gas market is focused on the efficient use of natural resources, observing safety standards, and causing the minimum environmental impact. Under this premise, new oil reservoirs in the Gulf of Mexico follow this trend in operation and production; therefore, it is necessary to study in detail the processes to comply with these standards to become a leader for future installations.
The proposal for this paper is to discuss technical aspects of the process design used for a "Production, Drilling, Utilities, and Quarters" (PDUQ) facility located at the southeast basin of the Gulf of Mexico. Specifically, the challenges associated with the handling and disposal of NGLs.
The process systems were designed based on the well composition and the PVT analysis.
While the gas is compressed in different compression stages, the natural gas heavier compounds are condensed due to the intrinsic hydrocarbon’s nature, forming NGL; this is vaporized at the storage tanks, and then sent either to the flare or back to the VRU, wasting energy. Also, heavier gas components would condense into the pipeline, and consequently, the pressure drop would increase, demanding an increase of pigging operation’s frequency.
The base case study has considered mixing the NGL with the sales gas, giving, as a result, the accumulation of liquids in the sales gas pipeline. For such reason, to avoid potential operational problems, two cases study for handling and stabilizing NGL were developed to analyze the potential use of NGL to increase oil production and improve its API gravity.
Case 1-Transferring produced NGL to oil train, consists of mixing the NGLs in the intermediate pressure separation stage to capture the heavier compounds, increasing the oil production and improving its API gravity.
Case 2-Stripping NGL to increase gas production, develops a process to handle and stabilize the NGLs, and then to mix them with the crude oil.
From both cases, additional oil production, better API gravity, and reduction of liquids in the sales gas were obtained. The results indicate that the strategy selected for Case 1 produces a higher increase in oil production and further improves its API gravity, however the power and duty requirements are higher. Additionally, the export gas quality is improved, and the pressure drop in sales gas pipeline is reduced; therefore, lower frequency on pigging operations is required.
A preliminary economic assessment is developed considering CAPEX, OPEX, ROI, Net present value, and investment efficiency. Based on this assessment, Case 1 is found to be the most profitable solution.