Energy & Fuels, Vol.30, No.9, 7524-7531, 2016
Reducing Gas Flaring in Oil Production from Shales
It is estimated that about a third of the total gas produced from the prolific Bakken Formation, amounting to about 250 million standard cubic feet (MMSCF)/day, is either vented or flared. The gas flared in the Eagle Ford formation in Texas is also of the order of 100 MMSCF/day. The main target in these plays is liquid (oil and condensate), and the associated gas is flared or vented. Any liquid production from shale will ultimately involve surface production facilities for stabilization, treatment, and transport of produced fluids. The design and operation of the surface production facilities affect the amount and quality of the liquid produced and significantly affect the amount of gas vented. In this paper, we show that using a two-stage design improves liquid quality while reducing venting rates by up to 70%. The two-stage operation will require additional infrastructure and cost upfront but will yield considerable technical and environmental benefits and move tight oil production to a more sustainable operation. The impact of operational change in surface facility and wellhead on the sub-surface flow is also investigated in this study by simulating a conventional condensate process flowsheet with Eagle Ford fluid. Major pressure drops occur in the vertical section of the well and in the wellhead choke valve, where a change in the flow regime is observed. Up to 10% liquid fallout inside the reservoir causes a loss of production and creates a condensate bank near the wellbore, hindering the gas flow.