Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract A new downhole tool has been developed to indicate the presence of gas in the mud immediately above the drill bit. The new tool has many potential applications beyond the early anticipation of a kick. For instance, under favorable conditions, shallow gas bearing sands can be located without interrupting drilling operations. Consequently, drilling schedules and mud programs can be optimized for safe and programs can be optimized for safe and efficient rig operation. No electronics is used in the downhole gas detector and no modification of the drill string is necessary. operating the tool requires only a minor variation in routine drilling operations. Introduction Whenever formation gases flow into the well bore during drilling operations, a potentially hazardous condition exists. As the gas rises up the well with the drilling mud, it expands, reduces the apparent density of the well fluids and, consequently, reduces the pressure which the mud can exert pressure which the mud can exert against drilled formations. Most often, the reduction of hydrostatic pressure is small and the flow of gas into the well is quickly stopped by the buildup of a mud cake on the bore walls. However, if the initial amount of gas which enters the well as the bit cuts into the formations is high or if the mud density is abnormally low, the reduction in the well fluid hydrostatic pressure caused by the expansion-of the pressure caused by the expansion-of the gas permits more gas to enter the mud system. The additional gas causes a further reduction in the hydrostatic pressure and a corresponding additional pressure and a corresponding additional flow of gas. Unless the well is closed off, a blowout situation quickly develops. It is obviously very important to measure as accurately and as early as possible how much gas is being added to possible how much gas is being added to the mud stream near the bit in the process of drilling. If the amount is process of drilling. If the amount is small or if the flow is only temporary, the situation will correct itself and there is no reason to stop drilling operations. However, if the flow of gas is steady, it is inevitable that a dangerous condition is developing and immediate measures must be taken. Even when the gas kick is kept under control, the time required to correct the situation and the costs incurred to do so increase rapidly with the amount of gas which is permitted to enter the well bore. The laws of physics which apply to the expansion of formation gases in the well bore do not permit a simple and early detection of the kick.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.