Low Pressure Metering of Natural Gas

摘要

Many regions of the USA have many natural gas wells that are declining in both flow and pressure due to extensive exploitation and production over many years, horizontal drilling has brought new life to these regions however some regional production sites may not be capable to be rejuvenated which leaves them in a state of low output. These traditional wells which are showing symptoms of reduced pressure and flow-rates, may need to implement a change in scope and design criteria of the metering station or central receipt point (CRP) these are usually designed around the API 14.3 - AGA 3 measurement standard for pipeline quality gas. The quality of gas now being seen at many of these upstream area stations generally does not meet the measurement quality requirements as recommended in these design standards. The situation gets worse and sometimes the issue can be passed downstream to the transporter were the BTU values of these wells are intermingled with newer or re-energized horizontally bored developments. Traditional energy supplies have also been enhanced in recent years by the addition of coal bed methane which has easy access in shallow and deep coal seams worldwide. Such places as Russia, India and Australia are all reviewing this efficient energy source as well as the USA. In fact, major sources of this clean product 'Natural Gas' has been discovered in all parts of the world. Some of the challenges that producers experience relates to providing cost effective accurate measurement at the wellhead whilst maintaining a low differential pressure across the gas transportation system whilst also dealing with wet gas issues in the meter run, which can be subsequently passed on to the gas transporter or midstream operator. This paper describes various pieces of experiential data from the writer's involvement in this field over 30 years regarding allocation measurement of Natural Gas, particularly regarding the use of new types of differential pressure type meters as the primary differential pressure producer. Since the first natural gas wells drilled in the early 1900's, the expansion of the world gas supply has been dramatic with US holdings controlling approximately 55% of the worlds O&G production and exploration. New hydrocarbon product finds are being forced to more costly world regions with smaller yield rates and return on investment. Changes in drilling methods and new ideas are being conceived to help produce the energy requirement we need, the move to compressed natural gas (CNG) as a clean energy source for automobiles is a natural and cost-effective solution. Major Hydrocarbon supply companies are involved in both producing mineral wealth and energy wealth, the two being interlinked by a common factor Natural Gas whose main constituent is CH4 methane.