A Small Volume Sampling Technique (SVST) allows operators to perforate, record temperature and pressure, and collect a formation sample prior to or in lieu of a well test efficiently and economically. Using this method, formations can be tested on a preliminary basis without the logistical burden of a comprehensive well test. Because of its economy, the SVST can also be used to test zones that were bypassed in older wells when expected production was not considered worth the expense of a comprehensive well test. The test apparatus is run in on drill pipe or tubing. Test procedure consists of Collection of two samples also yields valuable drawdown and pressure buildup data from two flow periods and two closed-in periods. After the tool is retrieved to the surface, an approximate liquid-gas ratio and water cut can be determined while the sample is drained. PVT analysis is then performed in the lab on samples taken by the small PVT samplers.
Safety and economy of offshore operations have been improved by application of a ball-type storm valve system (SVS) that can be installed without left hand rotation, thus eliminating the danger of unscrewing drill pipe joints. The new valve system is latched by setting an overshot down over a stinger and applying weight; releasing is accomplished by right hand rotation and lifting. A retrievable test, treat, and squeeze packer is installed below the valve. Design of the ball-type SVS offers these advantages:Ease of operation. When the system is set down, the ball valve automatically closes to shut the well in. Latching onto the system is accomplished without opening the ball.Since the ball valve is not opened by latching on for removal, it can be closed by setting back down in the event high pressure is detected below the SVS.Wireline equipment can be run through the SVS.High volumes of drilling fluid may be circulated through the SVS to condition the mud system prior to removing the SVS from the hole. Present paper discusses design of the valve, with operational schematics illustrating its operation. Field results are presented describing use of the SVS in stress situations and for some maintenance functions, and resumption of operations. Rig time savings are discussed. Background General To aid in rapid and safe abandonment of offshore drilling platforms and floaters in the path of oncoming storms, operators have used a variety of storm valves that enabled them to leave the drill string in the well until the storm was over. Some operators have also used the storm valves to assist in wellhead replacement and performance of maintenance to the blowout preventer (BOP) stack. Assuming that the drill string of an offshore well drilled to 8,000 ft had to be pulled to protect against an oncoming storm or for other reasons, about $16,000 in rig time could be saved on a floater, and about $8,000 could be saved on a jackup rig if the trip could be avoided by use of a storm valve. Retrievable Bridge Plugs Cup-type retrievable bridge plugs can be used as storm safety devices, however their use necessitates removal of the drill string. The weight of the drill pipe may require that it be laid down for riding out the storm. These plugs are set 250 to 300 ft below the mud line, and will keep the well under control even if the BOP stock is broken off. After the storm passes, the plug is removed and pressure is bled off. Balanced valve type plugs are best suited as storm valve devices since pressure may build up from below the plug. Hang-Off Tools The simplest of all storm safety devices is a hang-off tool, which supports the weight of the drill string by hanging onto the bare protector at the bottom of the BOP stack. Although this method avoids removal of the drill pipe from the well, it provides no well control should the BOP stack be knocked off. Retrievable Packers and Valves. Retrievable packers, in conjunction with a check valve or a balanced valve, may be used as storm safety devices. Two variations are used. P. 163^
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
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.