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Results
Experimental Study of Friction and Cutting Transport in Non-Circular Borehole Geometry
Taghipour, Ali (SINTEF Petroleum Research) | Lund, Bjørnar (SINTEF Petroleum Research) | Ytrehus, Jan David (SINTEF Petroleum Research) | Opedal, Nils (SINTEF Petroleum Research) | Carlsen, Inge M. (SINTEF Petroleum Research) | Skalle, Pål (NTNU) | Saasen, Arild (Det Norske Oljeselskap/ University of Stavanger) | Reyes, Angel (BG Group) | Melchiorsen, Jens Chr. (DONG E&P) | Abdollahi, Jafar (Statoil)
Abstract Torque & drag and hole cleaning are important parameters to control during drilling operations, but the effect of wellbore geometry on these parameters are not fully explored. This paper presents results from an experimental study of torque and cutting transport in two different wellbore geometries; one circular and one non-circular, where spiral grooves have been deliberately added to the wellbore wall in order to improve cuttings transport. Improving borehole hydraulic and mechanics will improve drilling efficiency in general, and will in particular enable longer reach for extended reach drilling (ERD) wells. The experiments have been conducted as part of an R&D project where the goal was to obtain reduced friction and improved borehole hydraulics and hole cleaning for more efficient drilling and well construction. The experiments have been performed under realistic conditions using a flow loop which includes a 12 meter long test section with a 2" OD freely rotating drillstring inside a 4" ID wellbore made of concrete. Solid particles were injected while circulating the drilling fluid through the test section at two inclinations; horizontal and 30° inclined from horizontal. The test results show that drillstring torque is reduced and cutting transport is improved in the non-circular wellbore relative to the circular wellbore. The experiments show up to 40% reduction in dynamic pressure drop for similar hole cleaning conditions of a non-circular geometry. In addition, the results show that the torque decreases by up to 15% in the non circular geometry relative to the circular geometry. The difference in torque is attributed to the reduced contact area between drillstring and wellbore for the non-circular geometry. Such a comparative, experimental study of hole cleaning in different wellbore geometries has to our knowledge previously never been performed, and the results were obtained in a custom-made and unique experimental flow loop. The results and the experimental approach could therefore be of value for any one working with drilling. The results show that a non-circular wellbore with spiral grooves can improve borehole hydraulics and mechanics.
- North America > United States (1.00)
- Europe (1.00)
- Asia (0.93)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (1.00)
Post-Well Shale-Stability Modeling and History Matching in Norwegian North Sea
Nes, Olav-Magnar ((currently with Det Norske Oljeselskap ASA)) | Bøe, Reidar (SINTEF Petroleum Research) | Sønstebø, Eyvind F. (SINTEF Petroleum Research) | Gran, Kjetil (Det Norske Oljeselskap ASA) | Wold, Sturla (Det Norske Oljeselskap ASA) | Saasen, Arild (Det Norske Oljeselskap ASA and University of Stavanger) | Fjogstad, Arild (Baker Hughes A/S)
Summary Severe borehole-stability problems were encountered in a recent exploration well in the Norwegian North Sea. The problems occurred when drilling through Tertiary shale sections interbedded with permeable sand layers. Drilling was initially performed with water-based mud (WBM). However, because the section target was not able to be reached after more than 2 weeks of operation, the section was plugged back, and a sidetrack was drilled with an oil-based mud (OBM) without encountering major operational problems. On the basis of the post-drill analysis of drilling data, well logs, drill cuttings, and borehole cavings sampled from the well, this paper describes how the complex combination of drilling-fluid salt concentration and geological constraints may be used to ensure successful future drilling operations in this part of the North Sea. Cuttings and preserved cavings collected during the drilling operation were selected from several depth intervals identified as potentially troublesome from drilling experience and log data. The determination of cuttings mineralogy enabled a better prediction of how the time dependency of the stable drilling-fluid-density window is influenced by an interaction between the shale and the drilling fluid. Mechanical strength is a key input parameter when predicting borehole stability. Dedicated rock-mechanical punch measurements on cavings were used to confirm the prediction of strength from log data alone. The examination of caving surfaces revealed the possible presence of in-situ-fractured rock. Such fractures would require special measures while drilling to maintain stability. Subsequently, a borehole-stability sensitivity analysis was performed that focused on time-dependent stability in the shale formations. The analysis used cuttings and cavings properties and logs as input. In particular, the modeling showed how the optimal potassium chloride (KCl) concentration in the drilling fluid changes with depth. The modeling further identified a relatively large sensitivity toward borehole inclination—even at fairly small inclinations. This paper thus illustrates the significance of properly accounting for rock-mechanical aspects when planning new wells.
- Europe > United Kingdom (1.00)
- Europe > Norway > North Sea > Central North Sea (0.28)
- Europe > United Kingdom > North Sea > Central North Sea > Egersund Basin > PL 038 > Sleipner Formation (0.99)
- Europe > United Kingdom > Atlantic Margin > West of Shetland > Faroe-Shetland Basin > Rona Ridge > Block 206/9 > Clair Field (0.99)
- Europe > United Kingdom > Atlantic Margin > West of Shetland > Faroe-Shetland Basin > Rona Ridge > Block 206/8 > Clair Field (0.99)
- (23 more...)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
Abstract Plug and Abandonment (P&A) can easily contribute with 25% of the total costs of drilling exploration wells offshore Norway. The costs of running a P&A operation on some offshore production wells may have a cost impact similar to the cost of the original drilling operation. Therefore, cost efficient P&A technology is necessary to reduce cost. In this paper, qualified technology and materials for P&A is reviewed to act as a basis for P&A planning. This paper describes in detail requirements for P&A operations offshore Norway as well as normal practices for P&A. Well construction issues related to minimising the need for later P&A operations like proper primary cementing planning is discussed. P&A techniques and materials for P&A operations are reviewed to act as background information for future P&A planning on the Norwegian continental shelf. These techniques include operations ranging from milling to washing and squeezing cement or other materials. The materials being reviewed include swollen shale, concentrated sand, metal plugs like bismuth, as well as improved conventional cement systems. This work presents an overview of the well plugging and abandonment challenges, innovative potential barriers and case histories on the Norwegian continental shelf. Introduction Oil and gas wells at some time in their life will be plugged and abandoned. Improperly abandoned wells can become a significant threat to the environment if they are not constructed or sealed properly. Plugging material (barrier) may fail during or after placement. Barrier failure can be caused by: natural fractures/faults, tectonic stresses, improper plug placement or materials used. In brief; isolation outside casing, collapses and sustained casing pressure are main well integrity challenges with respect to Plug and Abandonment (P&A). The quality and performance of a P&A operation may be investigated by two points of view; type of plugging material and plug placement technique. Barriers may be categorized as cementitious or mechanical barriers. It should be noted that mechanical barriers are used as temporary P&A barriers and not allowed to be used as permanent barriers. Type of material used defines the type of plug placement technique. There are several cement plug placement techniques that are used in the abandonment process (Smith 1993; Nelson 2006):Balanced method, Dump-bailer method, Two-plug method, and Jet grouting. The following tools are used for placing cement plugs:Flexible bags, Inflatable through-tubing packers, and Umbrella-shaped membranes (Nelson 2006). Local practices, government regulations, company policies and well conditions lead to variations of the above-mentioned tools and methods.
- North America > United States > Texas (0.69)
- Europe > United Kingdom > North Sea (0.42)
- Europe > Norway > North Sea (0.42)
- (2 more...)
- Geology > Structural Geology > Tectonics (0.56)
- Geology > Geological Subdiscipline > Geomechanics (0.49)
Abstract Plug and Abandonment (P&A) can easily contribute with 25% of the total costs of drilling exploration wells offshore Norway. Cost efficient P&A technology is therefore necessary to reduce cost of exploration drilling. In this paper, qualified technology for cutting and retrieval of wellheads using a separate vessel is described in detail. It is shown how to use this technology to significantly reduce the total costs of exploration drilling. The technology has now been used on several abandonment operations on the Norwegian continental shelf. In the paper it is presented through examples how efficient P&A operations are run using a dedicated vessel to perform parts of the wellhead cutting and retrieval operation earlier conducted with the drilling rig. Examples illustrate how the different wells are permanently plugged back to maintain all barrier requirements before the drilling rigs leave the wells with wellheads in place. During a later wellhead removal campaign a dedicated vessel arrives cutting the casings underneath the sea bed and finally removes the wellheads. It is shown that removal of more than two wellheads in a campaign is necessary to make this type of operation cost efficient. Introduction By transferring activities like Plug and Abandonment (P&A) and anchor handling from rig to dedicated vessels, the cost of drilling operations will be reduced and drilling production will be increased (Sørheim et al., 2011). The objective of transferring these activities to the dedicated vessels is to maintain the drilling rig activity at their core functions, which are drilling and completing wells. For example, in offshore drilling operations it is generally more cost effective to pre-set anchors prior to arrival of drilling rigs than to let the rig be an active part in anchor handling (Saasen et al., 2010). Similarly it can be efficient to pre-set conductors prior to rig arrival. As mentioned, permanent P&A is also an operation where activities can successfully be moved from rigs to dedicated vessels. In addition to the economical benefits of moving activities to dedicated vessels, there is a significant Health, Safety and Environment (HSE) benefit. These transferred activities are now conducted by specialised personnel on dedicated vessels. On the rigs these activities will be parallel to other rig activities and thereby represent a slightly higher HSE risk. Going and Haughton (2001) presented tools for casing string recovery including casing cutter, a hydraulic casing spear and a combined marine swivel/hanger seal extractor have been presented earlier. This system has successfully been used on drilling rigs to remove casing strings and wellheads. P&A without the use of drilling rigs is currently a routine operation on land wells. See for example Tettero et al. (2004). These techniques however, are not straightforward in offshore operations. P&A of offshore exploration wells represents a significant part of the drilling cost especially for production wells. Normally these operations are conducted by removing completion equipment followed by placement of a series of cement plugs. This application of cement plugs is described by for example Liversidge et al. (2006). Also, while drilling exploration wells, the P&A operation is a significant cost. Therefore, a method using a concentrated sand slurry for P&A of the reservoir has been applied to minimise the time to wait for the cement to cure (Saasen et al., 2011). In the following it is shown how parts of the P&A operation successfully have been transferred from the rig to a dedicated vessel and thereby reduced rig time on non-drilling activities.
- Europe (1.00)
- North America > United States > Texas (0.48)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drilling Equipment (1.00)
- Well Drilling > Casing and Cementing > Casing design (1.00)
- (3 more...)
Solids Control Device Optimised For Proper Occupational Hygiene
Larsson, Andreas (Maersk Drilling) | Blikra, Harald (Talisman Energy) | Florvaag, Magnus (Dong Energy) | Vasshus, Jan Kristian (Cubility) | Malmin, Arne (Cubility) | Grelland, Tore (Cubility) | Stokknes, Arne (Cubility) | Saasen, Arild (Det norske oljeselskap and University of Stavanger)
Abstract To obtain acceptable working environment in the shaker room has been a long lasting challenge. A new solids control system based on a vacuum conveyer system (VCS) has been developed to meet this challenge. The VCS uses a slowly rotating screen. Instead of using high gravity forces as being done on conventional shale shakers, the VCS uses a horizontally vibrating screen with a pressure difference to separate drilling waste from the drilling fluid. The use of this technology has several benefits. The absence of the high G collision forces reduces degradation of cuttings sizes and thereby reduces the fluid on cuttings. The VCS has a self cleaning device preventing blinding of the screen. The solids control system is built into an enclosed cabinet eliminating hydrocarbon mist and vapour. Furthermore, the system significantly reduces vibrations in the shaker room. The current paper outlines the VCS performance on the first series of regular applications on the jack-up drilling rig Maersk Giant. The improved occupational hygiene conditions are verified along with proper solids control performance.
- Europe (1.00)
- North America > United States > Texas (0.47)
A New Fluid Management System and Methods for Improving Filtration and Reducing Waste Volume, Introducing a Step Change in Health and Safety in the Mud Processing Area
Kroken, Asbjørn (Cubility) | Vasshus, Jan Kristian (Cubility) | Saasen, Arild (Det norske oljeselskap and the University of Stavanger) | Aase, Bodil (Statoil) | Omland, Tor Henry (Statoil)
Copyright 2013, SPE/IADC Drilling Conference and Exhibition This paper was prepared for presentation at the SPE/IADC Drilling Conference and Exhibition held in Amsterdam, The Netherlands, 5-7 March 2013. This paper was selected for presentation by an SPE/IADC program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers or the International Association of Drilling Contractors and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers or the International Association of Drilling Contractors, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers or the International Association of Drilling Contractors is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE/IADC copyright. Abstract Effective removal of contaminants from drilling fluids is widely accepted as a key factor in achieving optimum drilling performance and reducing fluid cost.
- North America > United States > Texas (0.46)
- Europe > Netherlands > North Holland > Amsterdam (0.24)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.48)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Pennsylvania > Appalachian Basin > Marcellus Shale Formation (0.99)
- (4 more...)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- Health, Safety, Environment & Sustainability > Health (1.00)