Utilization of Onsite Nitrogen Generation Technology as a Replacement for Conventional Liquid Nitrogen for Unloading Wells: a Novel and Cost Effective Alternative with Less Carbon Footprint on the Environment

Abstract

Abstract Nitrogen gas is one of the important consumables in demand in high volumes in the upstream oil industry. One of its regular uses is in the nitrogen unloading wells during kickoff operations to liven dead wells. Conventional methods use liquid nitrogen stored and transported in specially insulated vessels to be pumped into wells using sophisticated cryogenic pumps and equipment. Cryogenic equipment that operates at very low temperatures, poses several safety hazards such as causing cold burns when skin comes in contact with a severely cold object (liquid nitrogen is at -196 °C). This technical paper presents the successful utilization of in situ generated nitrogen gas at a wellsite as a replacement of the conventional requirement of liquefied nitrogen, storage and transportation system for liquid nitrogen, and cryogenic pumps and equipment for pumping nitrogen into the well. The paper will discuss briefly the membrane technology used to produce clean nitrogen at wellsites by drawing atmospheric air as the raw input; and the advantages of the continuous nitrogen generation technology over the conventional liquid nitrogen system. Introduction Nitrogen gas is being used heavily in the oil industry for various operations. Unloading and reviving oil wells by reducing the hydrostatic pressure created by the fluid column inside the wellbore by pumping nitrogen using coiled tubing units is a main practice nowadays in oil fields. The conventional method being used in such cases is utilizing liquid nitrogen stored and transported in specially insulated vessels to be pumped into wells using sophisticated cryogenic pumps and equipment. This method poses some disadvantages such as gas consumption efficiency, high cost and limited quantities at wellsites especially in remote areas. Also, it positions serious safety concerns such as cold burns and accidents while transporting the liquid nitrogen. To overcome the disadvantages and minimize these safety hazards, this new approach of using onsite nitrogen generation by separation of nitrogen from the air by selective permeation through a bundle of hollow fibers has been trial tested in Ghawar field, Saudi Arabia, to meet the demand for high volume and eliminate the troublesome logistics and timing of supply while delivering liquid nitrogen to wellsites; especially in remote areas.