Hussain, Sajjad (Schlumberger) | Dhaher, Karam Sulaiman (Schlumberger) | Bjoerneli, Hans Magnus (Schlumberger) | Blackburn, Jason (Schlumberger) | Monterrosa, Leida (Schlumberger) | Jakobsen, Tom (Statoil ASA) | Otto Monsen, Gisle (Statoil ASA) | Haaland, Sigurd (Statoil ASA) | Dahl, Johan (Statoil ASA) | Østensen, Ståle (Statoil ASA) | Fjelde, Kjell Kåre (University of Stavanger)
AbstractOld platforms are not well known for extended-reach drilling (ERD) operations mainly due to rig and hydraulics limitations. ERD wells demand robust rig capabilities, good hydraulics systems, and equipment reliability. In addition, the well profile, rotary steerable system (RSS), measurement-while-drilling (MWD) and logging-while-drilling (LWD) tools, surveying, and new technologies are extremely important to the success in drilling an ERD well. RSS and drillpipe selection are important factors for hydraulics optimization. Surveying techniques are also important for time saving and improved efficiency. An ERD well in the North Sea Statfjord field was kicked off in the 17 ½-in. section from the openhole cement plug through a 50-m window between the 20-in. casing shoe and 13 3/8-in. casing stump, ensuring a smooth well profile and reduced doglegs compared to the whipstock window exit. The 17 ½-in. section was drilled and landed at a 79° inclination using point-the-bit RSS technology, and the 12 ¼-in. section was drilled in two runs as planned using the point-the-bit RSS withstanding more than 550 h down hole. The 9 5/8-in. liner was run and floated successfully in the ~6000-m section. Strict adherence to surveying techniques and quality control processes proved very helpful to meet Operator technical requirements. The 8 ½-in. section was drilled and landed on top of the reservoir with an inclination decrease from 88° to 35°. New MWD technology was successfully used in drilling the 6-in. section. These latest technologies as well as employing appropriate techniques help to drill ERD wells on aged platforms like those in the Statfjord field. This paper will describe the planning and execution phases of a challenging ERD well drilled in the Statfjord field.
Hussain, Sajjad (Schlumberger) | Huelvan, Yvon (Schlumberger) | Labrousse, Sebastien (Schlumberger) | Hassan, Haitham Khalil (Schlumberger) | Esmat, Mohamed (Schlumberger) | Dhaher, Karam Sulaiman (Schlumberger) | Blackburn, Jason (Schlumberger)
AbstractRathole elimination (RHE) BHA comprised of hydraulics and ball-drop underreamer has been used in different North Sea fields. RHE success has been very important for operators in completion, cementing, casing running optimization, and handling contingencies by running intermediate liners and casings. One of the major benefits of the RHE system is time saving because the rathole is removed in the same drilling run and the dedicated underreaming run is not required. In today's field operations, this time saving has become considerably important on the older platforms as well. An RHE system has been successfully run on the North Sea continental shelf (NCS) with five different operators and in six challenging fields, resulting in significant time and cost saving for each operator. BHA and hydraulics design are the basis of these successful RHE operations. Starting from a vertical well to whipstock exits and 2D wells followed by 3D complex wells have established that the RHE system is fully directional and steering capability is not compromised by BHA complexity. Suites of applications, including the integrated dynamic design and analysis 4D platform was used for BHA optimization and stability, underreamer and bits cutting structure selection, and directional response prediction. Both push-the-bit and point-the-bit rotary steerable systems (RSS) have been used in these operations. RHE showed great success and technology maturity on NCS in various borehole sizes. This paper presents the historical run summaries and the technology maturity life cycle in the North Sea.
Hussain, Sajjad (Schlumberger) | Li, Fei (Schlumberger) | Rana, Vikram (Schlumberger) | Sharma, Varun (Schlumberger) | Dhaher, Karam Sulaiman (Schlumberger) | Blackburn, Jason (Schlumberger) | Haaland, Sigurd (Statoil ASA) | Sivertsen, Atle (Statoil ASA) | Eshraghi, Daniel (Statoil ASA) | Dashtpour, Reza (Statoil ASA) | Lunkad, Siddhartha (Statoil ASA) | Hongdul, Thanong (Statoil ASA) | Bairwa, Girish Kumar (Statoil ASA)
The point-the-bit rotary steerable system (RSS) is frequently used for high-profile directional drilling jobs in challenging environments that require high degree of directional control.
To achieve toolface control, the point-the-bit RSS control system requires two inputs: the rotation rate of the collar (CRPM) and the toolface orientation of the bit shaft. Previously, the tool utilized magnetic field measurements to compute the above two parameters and, subsequently, control the toolface for the well trajectory. However, the point-the-bit RSS steerability is compromised in a blind zone (where magnetic field measurement is significantly interfered with, such as inside casing, drilling out of a whipstock window, or close to offset wells, or does not have enough signal strength, such as in a zone of exclusion (ZOE) where the Earth's magnetic field projection on the cross section of tool is low. The new inertial steering mode of the point-the-bit RSS uses accelerometers and a rate gyroscope sensor to steer the tool, and it can be toggled on or off by a mud downlink. This inertial steering mode effectively expands the operational envelope of the point-the-bit RSS by improving tool steering ability when the tool is in a blind zone or ZOE.
Four successful field runs have been completed on one of the largest mature fields in North Sea Continental Shelf (NCS). In the first field run, the new inertial steering mode of the point-the-bit RSS was used to kick off a well, which is close to seven nearby producing wells, from an openhole cement plug through a 37-m narrow window between the 20-in. casing shoe and 13 3/8-in. casing stump and to drill a 17 ½-in. section in the same run. The new inertial steering mode helped to steer in the desired direction with good tool face control in the presence of high magnetic interference. In the second field run, the RSS tool successfully exited the whipstock window and steered in the desired direction using the new inertial steering mode, providing planned separation from the cuttings re-injection (CRI) zone and drilling the 12 ¼-in. section to target depth (TD). In the third field run, the new inertial steering mode was deployed to exit the whipstock window, drill the 8 ½-in. section to TD, and land on top of the reservoir close to five offset wells with a minimum 14-m center–to-center distance. The fourth field run helped the operator to exit whipstock window inside the 13 3/8-in. casing and steer the 12 ¼-in. section underneath motherbore in a high magnetic interference and collision risks environment.
Based on the four successful runs, the new inertial steering mode of the point-the-bit RSS has been proven for its tool face and trajectory control, expanding the tool's operational envelope.
The objective of this paper is to share the results obtained from in-depth analysis using a down hole mechanics and dynamics monitoring sub, which lead to the first successful Gullfaks Satellite 14 ¾ x 17 ½ -in Rathole elimination operation through challenging lithology.
Shallow gas is encountered in the Gullfaks South area at a true vertical depth of between 335-339m (from MSL), and a casing design incorporating a 16-in liner is utilized to isolate this interval. A 14 ¾ x 17 ½ -in section is then drilled to isolate weak and unstable formations, and in all previous wells this section was drilled with a two run strategy. The first run to drill to section target depth (TD) while hole opening, followed by a dedicated second run to open the rathole. An opportunity was identified to improve well construction performance by eliminating the dedicated run to open the rat-hole, and tailoring the bit design to overcome the challenging lithology and high levels of shock and vibration seen on offset wells.
Detailed pre-job planning and BHA design analysis was combined with new downhole technologies to overcome these challenges. Dual reamers were used within a Rotary Steerable System (RSS) BHA to drill the 14 ¾ x 17 ½ -in section and eliminate the rat-hole in one run. This innovative approach involved drilling to section target depth (TD) using an upper ball drop reamer, tool positioned 45 meters behind the bit for hole enlargement while drilling, and then pulling back to position the bit at rat-hole shoulder. At this point the upper reamer was de-activated and a lower on demand hydraulically activated reamer, mounted directly above the RSS was opened to eliminate the rat-hole. Due to excessive shocks & vibrations experienced on offset wells, a down hole drilling mechanics & dynamics sub was utilized to provide real-time information about downhole forces and BHA motions, combined with a tailored bit design to control depth of cut in sandy intervals. This unprecedented approach resulted in 2.5 days saving.
The main objective of this paper is to share the experience of the first Dual reamer bottom hole assembly (BHA) design implemented off-shore Norway, Gullfaks field, 17 ½ × 20-inch section. It presents the drilling challenges, innovative bottom hole assembly and the first world wide application for the Electro-magnetic receiver sub fully integrated with rotary steerable system (RSS)
Hole enlargement while drilling (HEWD) became a well-known application, and they are widely used to support several well intervention objectives like; i) Accommodating un-common casing design. ii) Reduce operational risk such as high equivalent circulating density (ECD). iii) Optimized casing and completion programs. There are two main types on hole enlargement tools, based on activation mechanism: ball-drop using a ball to Activate/De-activate the reamer, and hydraulic on demand triggered by changing flow rate on a predefined specific range, so called ‘Indexing’ for Activation/De-activation of the reamer. Both carrying a common implicit risks and limitations, where reamers have to be positioned above logging while drilling tools (LWD) so that the enlarged hole does not impair the quality of the formation evaluation measurements, or compromise the bottom hole assembly stabilization. This results in a rat-hole of 40-50 meters at the section target depth (TD), consequently challenges the casing running, casing cementing job, and drilling next sections with potential risk of cement pack-off around bottom hole assembly. Today in the industry, these challenges are usually addressed by an extra dedicated run for opening the rat-hole.
Collaborative efforts between operator in the North-sea and a Service Company to address the risk and limitations associated to the hole enlargement while drilling design. Dual Reamer System developed to reduce the rat-hole length to minimum instead of 40-50 meters, and to eliminate the extra dedicated run for opeing the rat-hole. The innovative approach planned to drill to section target depth (TD) using upper ball drop reamer, tool positioned 45 meters behind the bit for Hole Enlargement While Drilling, then pull back to position the bit at rat hole shoulder, de-activate upper reamer (ball drop system), and activate the lower hydraulic on demand reamer to eliminate the rat-hole. A Gyro while drilling integrated into the BHA along with 9-in world first electro-magnetic receiver sub mounted on the top of the hydraulic on demand reamer. Providing a full integration, and securing a real time communication with the RSS in a critical and challenging Anti-collision situation.
The unprecedented approach successfully implemented on Gullfaks field, 17 ½ × 20-inch section drilled to target depth (TD) in one run, with all objectives met on directional control in tight Anti-collision scenario, and measurements and logging while drilling.
The Dual reamer BHA along with the Electro-magnetic receiver sub proven efficient steering capability and reliability, which led to significant improvement in the drilling, casing running and cementing operations
Hussain, Sajjad (Schlumberger) | Dhaher, Karam Sulaiman (Schlumberger) | Bjoerneli, Hans Magnus (Schlumberger) | Noekland, Magnar (Schlumberger) | Blackburn, Jason (Schlumberger) | Monsen, Gisle Otto (Statoil ASA) | Haaland, Sigurd (Statoil ASA) | Hongdul, Thanong (Statoil ASA)
In recent years, slot recovery to drill more wells in brownfields has posed different challenges due to extensive and time consuming Plug and abandonment (P&A) and casing cut and pull operations [SPE 173954].
In 2013, For the first time on Statfjord Field, a ruggedized point the bit rotary steerable system (RSS) and Gyro while drilling (GWD) were used to sidetrack off cement plug in 17 ½-in hole section through a narrow window (80m) between 20-in casing shoe and 13 3/8-in casing stump. This reduced risk and saved time by sidetracking and drilling the section in one run. In similar scenarios on previous wells, mud motors had been used to kickoff and sidetrack from a cement plug between the casing shoe and casing stump. Two runs were always required to complete the sections; first run with a dedicated sidetracking assembly (motor BHA) and a second run with a drilling assembly (RSS BHA). After this success another attempt was made in 2014 where 17 ½-in section was sidetracked and drilled to TD through 40m narrow window between 20-in casing shoe and 13 3/8-in casing stump in high well collision risk environment. Significant time and cost saving was achieved on this project. In 2015 a challenging well was planned where kick off had to be done through 37m window and close to six producers. Due to high risk of collision and no possible option of whipstock exit, new Point the bit RSS technology was employed to kick off in high magnetic interference environment and drill the section in one run.
With the ruggedized point the bit RSS and GWD service, it was possible to constantly monitor direction and inclination in real time and thereby tracking the trajectory progress in the loose formations at shallow depth. This allowed to guard against dropping back to the mother bore and hitting the 13 3/8-in casing stump. Sidetracking in open hole from cement plug also increased formation strength at 20-in casing shoe and saved time/cost compared to whipstock exit.
During execution all three wells were sidetracked successfully from motherbores in the first attempt and drilled to section TD in one run saving significant rig time and cost.
This paper discusses the planning and execution phases of these three successful reentry wells drilled on Statfjord Field, one of the largest field on North Sea Continental Shelf (NCS).
Hussain, Sajjad (Schlumberger) | Dhaher, Karam Sulaiman (Schlumberger) | Blackburn, Jason (Schlumberger) | Islam, Mohamed Esmat (Schlumberger) | Salman, Kamal (Schlumberger) | Downie, Simon (Schlumberger) | Haaland, Erik (Schlumberger) | Monsen, Gisle Otto (Statoil ASA) | Haaland, Sigurd (Statoil ASA)
Statfjord field, one of the largest and oldest fields operating in the North Sea continental shelf, has been producing since early 1980s. It has three platforms, Statfjord A, B, and C, with more than 300 wellbores. Formation collapse (in the lower part of Shetland group) below casing/liner shoe in the overburden section on top of the reservoir has posed different challenges in the field. These challenges include problems in running screens and gravel packing in sand reservoirs. To respond to this challenge and focus on improving the drilling efficiency and rig cost savings, the drilling team evaluated drilling a 10 5/8 × 12 ¼-in. section reaching the top of reservoir—10 m true vertical depth (TVD) above the predicted top of the Mime formation—with minimum rathole. A standard underreaming bottomhole assembly (BHA) with one ball-drop reamer leaves a 35-m to 40-m rathole below the 9 5/8-in. casing shoe, which induces different issues related to casing reaching bottom, cementing, potential packoffs due to overburden formation collapse while drilling the 8 ½-in. section in reservoir, problems in running screens, and gravel-packing operations. On two previous wells, running screens faced some challenges, and gravel-pack efficiency was compromised. To cope with these technical challenges, an integrated dual-reamer rathole elimination (RHE) BHA was proposed; this would reduce the rathole to 9 m. The proposal was accepted by the operator after detailed risk assessment.
This section was planned to be drilled across formations in the Hordaland group building from 16° inclination to 30° inclination at landing on top of reservoir. To achieve the required directional control, a push-the-bit rotary steerable system (RSS) was selected. The dual-underreamer BHA with a ball-drop reamer above the surveying/logging tools and a hydraulic reamer on top of the RSS was selected to drill and underream the section in one run by minimizing rathole to 9-m. Dropping wireless communication across hydraulic underreamer made it possible to minimize the rathole to 9-m with some additional, but manageable, risks. Blind downlinks to the RSS, no real-time (RT) updates from the RSS and hydraulic underreamer, and compromising RSS steerability were the main risks identified at planning stage and agreed with the operator based on the controlling/mitigating measures in place.
The Statfjord drilling team successfully addressed these challenges with an innovative solution using the dual-reamers RSS BHA to drill the 10 5/8 × 12 1/4-in. section and remove the rathole in one run. Planned interval (~900 m) was drilled and underreamed to target depth (TD), with the ball-drop activated upper reamer, and the lower hydraulically activated reamer remained redundant. At section TD, the string was pulled back to position the bit at the rathole shoulder, the upper ball-drop reamer was deactivated, and the lower hydraulic reamer was activated to remove the rathole. The 9 5/8-in. casing reached planned bottom with a successful cement job, and screens were run without any problem.
Bø, Øystein (ConocoPhillips) | Vikhamar, Petter (ConocoPhillips) | Spotkaeff, Matthew (Schlumberger) | Dolan, James (Schlumberger) | Wang, Haifeng (Schlumberger) | Dupuis, Christophe (Schlumberger) | Ceyhan, Adil (Schlumberger) | Blackburn, Jason (Schlumberger) | Perna, Ferdinando (Schlumberger)
The Ekofisk field, operated by ConocoPhillips Skandinavia AS, in the North Sea has been producing hydrocarbons since 1971 and receiving water injection since 1987. The field is very complex in terms of its fluid profile, which is further exacerbated because the reservoir is a fractured chalk with low matrix permeability. Major water flooding, expected to distribute the water randomly throughout the reservoir, has instead channeled water along specific paths dictated by the fractures.
Successful geosteering in such an environment is very challenging; knowledge of where the water zones are becoming a fundamental element to success.
A new deep directional resistivity (DDR) tool has been field tested in the North Sea. The device has a greatly enhanced depth of investigation over any other existing resistivity tool, is capable of detecting formation boundaries that often reach a distance of 100 ft true vertical depth (TVD) from the borehole, and is coupled with the ability to delineate multiple boundaries in any direction. The results from application of this tool within the Ekofisk field show that, even in very complex fluid cases such as in Ekofisk, it was possible to map the water zone, which was observed both below and above the reservoir to a distance of 90 ft TVD.
The implications of the tool are multi-fold. Mapping the formation and fluid boundaries up to 100 ft TVD provided the only clear picture of fluid displacement through the reservoir away from the borehole, greatly enhancing the overall picture of formation structure and faulting within the reservoir. Prior to intersecting the reservoir in the intermediate section, a deep and early detection of top reservoir also allowed for the possibility of optimizing the landing of the horizontal well, greatly reducing the risk of drilling out through the base of the reservoir, even if the formation were structurally higher than expected. The ability to observe the resistivity profile throughout a large vertical cross-section away from the borehole also provided a multilayered petrophysical evaluation of far greater complexity than traditional borehole logging could possibly deliver.
In a case study of the Ekofisk well, well 1, we describe how deep directional resistivity data were used for real-time geosteering of the well and interpretation of the reservoir. In addition, we describe how the data can be used for advanced reservoir analysis.