Abatement of GHG Emissions by Simplifying Field Architecture with Multiphase Flowmeters in Onshore US Shale: A Field Case Study

Abstract

Abstract Methane is a powerful greenhouse gas (GHG). Over 20 years, it is 80 times more potent at warming than carbon dioxide, with onshore conventional wellsite production facilities being the source of more than 50% of petroleum methane emission in the United States (US). An operator working in the gas condensate window of the Eagle Ford shale has been diligently looking for innovative transition technologies to help minimize methane emissions from wellsite sources. Other key sustainability attributes for the project were capex and opex savings while simplifying well-pad architecture. Leak detection and repair (LDAR) programs that identify unintended or fugitive emissions from equipment in an oil and gas facility are a traditional way to drive maintenance activities to reduce emissions. However, this is focused on detection rather than elimination. The operator typically configures well-pads with three to six wells with one test separator per well, resulting in multiple separators per well-pad. The switch from test separators to full gamma-spectroscopy/Venturi combination surface multiphase flowmeters (MPFM) was an ideal solution as it eliminates the need for so many test separators, thus eliminating valves, pneumatic devices, and connections responsible for most fugitive gas emissions on production well sites, while simultaneously delivering real-time monitoring, which provides repeatable and accurate fluid measurements. Over the course of a field trial, the MPFM performed within the uncertainty range specified by the operator and even helped identify bias errors with reference to a test separator to enable remediation. Additionally, the high-frequency data (up to 1 second) helped detect changes in flow behavior like slugging flow or slight changes in water cut. Financial incentive was a significant driver in assessing the MPFM as it provides a 50% reduction in capex per well by simplifying the equipment and pipeline infrastructure and the investment cost for ancillaries (space, power, manifolds, etc.). In addition, overall methane emissions were reduced by an estimated 67%, and the number of potential leak paths for fugitive methane was minimized. Using the field case study, the paper demonstrates how integrating the use of MPFM technology to reduce GHG emissions will bring more tangible results than leak detection and repair efforts. The study shows how emissions can be reduced by more than 72% in different scenarios, depending on the number of wells in a well-pad with one test separator. If the test separator is removed, the reduction can reach up to 92%. Simplifying well-pad architectures using MPFMs for well measurements while performing separation and liquid handling at centralized facilities minimizes the many connections and valves responsible for most methane fugitive emissions. New or retrofitted facilities can use this transforming technology as their cost has decreased significantly, and data are repeatable and accurate.