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Collaborating Authors
North Sea
Dissolver Treatments to Re-Instate Functionality of Subsurface Safety Valves in Water Injection Wells
Hatscher, S. T. (Wintershall Dea Norge AS) | Havrevoll, N. (Wintershall Dea Norge AS) | Herrmann, T. (Wintershall Dea Norge AS) | Gjersdal, S. (Wintershall Dea Norge AS) | Dzhuraev, D. (Wintershall Dea Norge AS) | Torsvik, M. (Wintershall Dea Norge AS)
Abstract The Downhole Safety Valve (DHSV) integrity tests of two water injection wells on the Nova subsea oil field on the Norwegian Continental Shelf failed after one month in operation. One of the two wells, W-1, also showed issues with the Injection Master Valve (IMV). The objective was to re-instate the functionality of all compromised valves as soon as possible. First, the root cause for the malfunction was to be identified. Several hypotheses were developed and assessed, including mechanical and chemical issues. Both injectors (W-1 and W-4) are completed in the oil leg of the reservoir and have been cleaned up to rig before an injection test was conducted. The wells were then suspended for several months prior to initial start-up and commencement of water injection. Although wax inhibition was used during the clean-up, wax deposition at DHSV depth could not be fully discarded. Monoethylene glycol (MEG) has been deployed for hydrate mitigation after the injection tests and during initial well start-up. Pressure data indicated that at least partially, a column inversion within the tubing, from water to hydrocarbons, occurred during the suspension period. This observation gave support to that wax or hydrate deposition might restrict the DHSVs' flappers' movement. Based on this hypothesis, an operation with an Inspection Maintenance and Repair (IMR) vessel was planned, organized and conducted within five weeks after the failed tests. The treatment concept included not only a wax dissolver, but also MEG and heated fluids to combine the benefits of temperature as well as chemical dissolution towards either potential type of deposit. Both wells were treated from the vessel as per plan. The operation successfully re-instated the functionality of all three compromised valves, allowing to safely commence water injection into the reservoir.
- North America > United States (0.47)
- Europe > Norway > North Sea (0.29)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.67)
- Europe > Norway > North Sea > Northern North Sea > North Viking Graben > PL 418 > Block 35/9 > Nova Field > Viking Formation > Heather Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > North Viking Graben > PL 418 > Block 35/9 > Nova Field > Rannoch Formation > Heather Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > North Viking Graben > PL 418 > Block 35/8 > Nova Field > Viking Formation > Heather Formation (0.99)
- (4 more...)
- Well Completion > Completion Selection and Design > Completion equipment (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Inhibition and remediation of hydrates, scale, paraffin / wax and asphaltene (1.00)
- Facilities Design, Construction and Operation > Flow Assurance > Hydrates (0.86)
Abstract Breidablikk is a green field on the Norwegian Continental Shelf that just started the preproduction drilling of 23 wells in two structures. We have two reservoir fluid samples from exploration wells in each structure with relatively high viscosity of 4 and 8 cP, respectively. Our dynamic reservoir simulations on the Breidablikk Field indicate that any change in the viscosity in each direction can lead to a 20 to 30% difference in oil recovery. Therefore, updating our reservoir models with the viscosity distribution in the field along with the drilling activities is important. Currently, our models assume homogeneous reservoir oil viscosities across each structure. In this study, our primary aim is to conduct a holistic evaluation of the reservoir oil viscosity, using multiple methods to determine the most effective approach for qualitatively mapping the oil viscosity across the field, distinguishing between the low- and high-viscosity regions. The technologies chosen for this assessment are standard mud gas data, advanced mud gas data, and analysis of oil extracts from cuttings, given they have previously demonstrated their capability to estimate fluid properties while drilling or within a limited time frame, as evidenced by the work of Cutler et al. (2022). The methods were compared using pressure/volume/temperature (PVT) measurements as a benchmark. As of today, this method is considered the most reliable to obtain reservoir fluid properties, and in consequence, these measurements serve as the reference viscosity values in the study. The results of our analysis in Breidablikk show that an approach based on advanced mud gas data provide an oil quality classification that distinguishes between high- and low-viscosity reservoir oils, using the ethane/n-pentane ratio as the best parameter correlated to reservoir oil viscosity in Breidablikk. The threshold for the two viscosity regions is identified from a reservoir fluid database from the Breidablikk-Grane area, and the oil viscosity region estimated from advanced mud gas data agrees well with the PVT measurements. The viscosity estimation using a standard mud gas approach based on methane to propane compositions indicates that this technology cannot correctly differentiate between low- and high-viscosity region wells in the Breidablikk Field. Hence, it is not recommended. Further findings from our analysis indicate that the utilization of oil-based mud, combined with a high drilling speed, significantly affects the quality of the cuttings in Breidablikk. Consequently, the application of traditional geochemical analysis methods on cutting extracts is challenging. Therefore, this method is not recommended for the qualitative identification of the viscosity region of a given well. Benchmarking all available technologies allows us to select a real-time, reliable, and cost-efficient method to qualitatively estimate reservoir oil viscosity in Breidablikk. The selected method is field-specific and not general for other heavy oil fields. In summary, providing an accurate reservoir oil viscosity mapping at an early stage in field development plays a crucial role in the further optimization of drilling targets and ultimately leads to improved oil recovery (Halvorsen et al., 2016; Maraj et al., 2021).
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.87)
- Europe > Norway > North Sea > PL 169 > Block 25/8 > Breidablikk Field > Tor Formation (0.99)
- Europe > Norway > North Sea > PL 169 > Block 25/8 > Breidablikk Field > Hod Formation (0.99)
- Europe > Norway > North Sea > PL 169 > Block 25/8 > Breidablikk Field > Heimdal Formation (0.99)
- (14 more...)
Abstract The industry is continuously challenged to improve the efficiency and safety of operations. This is evident over the last 30 years in the development and improvement of measurements acquired while drilling. However, this has, in general, until now not been applied to well integrity measurements such as casing integrity and cement evaluation, which have traditionally been acquired utilizing wireline deployment. This paper will show the results of a new drillpipe-deployed tool that can be run in parallel with existing well operations. The results from two differing North Sea wells will be compared to traditionally acquired wireline-deployed tools and will demonstrate that these measurements and the resultant interpretation can successfully be acquired on drillpipe. This allows for much improved efficiency of operations and, in fact, the ability to acquire this important data in well conditions and environments where it is difficult or, in some cases, impossible to log with conventional wireline techniques. Two wells were selected with different degrees of difficulty in terms of measurement acquisition and showing different well trajectories and mud types. Both wells were logged with both the new drillpipe-deployed technology and traditional wireline technology, allowing a direct comparison of the techniques and tools and paving the way for acceptance of the new drillpipe-conveyed technology. The new drillpipe-conveyed tool can be run anytime drillpipe is utilized in the well. A radial distribution of ultrasonic transducers arranged on the circumference of a drill collar allows for full azimuthal interpretation of the casing and cement while rotating the drillpipe. Analysis of the acquired data allows for the interpretation of caliper thickness and an evaluation of the material in the annular space behind the casing. In addition, the tool can provide casing collar location in real time and has the ability to orient downhole devices such as whipstocks, perforating guns, and oriented cutters. The two well examples conclusively demonstrate that the tool can be run in parallel with existing operations to minimize rig time and eliminate the need for a dedicated, standalone wireline operation. Also, the cement evaluation interpretation was comparable to the equivalent wireline technology. We will investigate which measurements and applications the new tool can be used for and where there may be further room for improvement.
- North America > United States > Texas (0.28)
- Europe > United Kingdom > North Sea (0.24)
- Europe > Norway > North Sea (0.24)
- (2 more...)
In complex geological settings and in the presence of sparse acquisition systems, seismic migration images manifest as non-stationary blurred versions of the unknown subsurface model. Thus, image-domain deblurring is an important step to produce interpretable and high-resolution models of the subsurface. Most deblurring methods focus on inverting seismic images for their underlying reflectivity by iterative least-squares inversion of a local Hessian approximation; this is obtained by either direct modeling of the so-called point spread functions or by a migration-demigration process. In this work, we adopt a novel deep learning framework, based on invertible Recurrent Inference Machines (i-RIMs), which allows approaching any inverse problem as a supervised learning task informed by the known modeling operator (convolution with point-spread functions in our case): the proposed algorithm can directly invert migrated images for impedance perturbation models, assisted with the prior information of a smooth velocity model and the modeling operator. Because i-RIMs are constrained by the forward operator, they implicitly learn to shape/regularise output models in a training-data-driven fashion. As such, the resulting deblurred images show great robustness to noise in the data and spectral deficiencies (e.g., due to limited acquisition). The key role played by the i-RIM network design and the inclusion of the forward operator in the training process is supported by several synthetic examples. Finally, using field data, we show that i-RIM-based deblurring has great potential in yielding robust, high-quality relative impedance estimates from migrated seismic images. Our approach could be of importance towards future Deep-Learning-based quantitative reservoir characterization and monitoring.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (1.00)
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > PL 046 > Block 15/9 > Volve Field > Shetland Group > Åsgard Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > PL 046 > Block 15/9 > Volve Field > Shetland Group > Svarte Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > PL 046 > Block 15/9 > Volve Field > Shetland Group > Sleipner Formation (0.99)
- (17 more...)
The SEG standard for causal seismic data specifies that the onset of a compression from an explosive source is represented by a negative number, that is, by a downward deflection when displayed graphically; see Figure P-6. This standard is historically based; early refraction first arrivals broke downward. A reflection indicating an increase in acoustic impedance or a positive reflection coefficient also begins with a downward deflection. This convention is called positive standard polarity and the reverse convention is negative standard polarity or reverse polarity. In the North Sea and some other areas the convention for zero-phase wavelet is reversed.
- Europe > United Kingdom > North Sea (0.30)
- Europe > Norway > North Sea (0.30)
- Europe > North Sea (0.30)
- (2 more...)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
The North Sea basin is a hydrocarbon-rich Northern European basin that is bordered by nine European countries. The countries bordering the basin are Britain, Iceland, Norway, Sweden, Denmark, Germany, Netherlands, Belgium and France. Over the years, the North Sea basin has had many companies invest in this location due to its lucrative reservoirs. The North Sea's resources are a mixture of liquid petroleum and natural gas. The British and Norwegian areas of the basin contain the largest oil reserves compared to the remaining sectors[1].
- Europe > Norway > North Sea (1.00)
- Europe > Netherlands > North Sea (1.00)
- Europe > Denmark > North Sea (1.00)
- Europe > United Kingdom > North Sea > Central North Sea (0.32)
- Geology > Structural Geology > Tectonics (0.51)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.34)
- Europe > United Kingdom > North Sea > Southern North Sea > Southern Gas Basin > Sole Pit Basin > Block 48/06 > West Sole Field > Rotliegend Formation (0.99)
- Europe > United Kingdom > North Sea > North Sea Basin (0.99)
- Europe > United Kingdom > North Sea > Central North Sea > Forties Formation (0.99)
- (4 more...)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Statoil Research Centre, the Norwegian Geotechnical Institute (NGI), Scripps Institution of Oceanography, the University of Southampton, and ExxonMobil Upstream Research Company are receiving the Distinguished Achievement Award for their contributions to the successful implementation of controlled-source electromagnetics (CSEM). Statoil Research Centre had the insight to provide the funding and support required to perform the first substantial CSEM experiment for directly detecting hydrocarbons. NGI provided modeling support for the initial test. The work was done by Harald Westerdahl and Fan-Nian Kong. Scripps provided various insights along with receivers for the first test.
- Geophysics > Seismic Surveying (0.32)
- Geophysics > Electromagnetic Surveying (0.31)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Equinor has made a complete set of data from a North Sea oil field available for research, study and development purposes. The Volve oil field, located 200 kilometres west of Stavanger at the southern end of the Norwegian sector, was decommissioned in September 2016 after 8.5 years in operation, more than twice as long as originally planned. The development was based on production from the Mærsk Inspirer jack-up rig, with Navion Saga used as a storage ship to hold crude oil before export. Gas was piped to the Sleipner A platform for final processing and export. Volve reached a recovery rate of 54% and in March 2016 the licence decided to shut down its production permanently.
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > Sleipner Field > Draupne Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > PL 046 > Block 15/9 > Volve Field > Shetland Group > Åsgard Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > PL 046 > Block 15/9 > Volve Field > Shetland Group > Svarte Formation (0.99)
- (18 more...)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
The first 2-D case study for structural inversion is from the Southern Gas Basin of the North Sea. Figures 10.1-1 and 10.1-2 show selected CMP gathers from the two segments of the line accompanied by the corresponding CMP stacked sections. The left segment (Figure 10.1-1) contains a salt diapir with relatively steep flanks and the right segment (Figure 10.1-2) contains a salt diapir which has a broader base. The Zechstein formation comprises a halite unit with a velocity of 4400 m/s and anhydrite-dolomite rafts of various sizes and shapes with a velocity of 5900 m/s. The strong velocity contrast across the top-salt boundary and the presence of the anhydrite-dolomite rafts within the diapiric formation itself give rise to raypath distortions and thus constitute a complex overburden structure.
- Europe > United Kingdom > North Sea (1.00)
- Europe > Norway > North Sea (0.68)
- Europe > North Sea (0.68)
- (2 more...)
- Geology > Structural Geology > Tectonics > Salt Tectonics (1.00)
- Geology > Mineral (0.96)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock > Dolomite (0.48)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Statoil Research Centre, the Norwegian Geotechnical Institute (NGI), Scripps Institution of Oceanography, the University of Southampton, and ExxonMobil Upstream Research Company are receiving the Distinguished achievement Award for their contributions to the successful implementation of controlled-source electromagnetics (CSEM). Statoil Research Centre had the insight to provide the funding and support required to perform the first substantial CSEM experiment for directly detecting hydrocarbons. NGI provided modeling support for the initial test. The work was done by Harald Westerdahl and Fan-Nian Kong. Scripps provided various insights along with receivers for the first test.
- Geophysics > Seismic Surveying (0.32)
- Geophysics > Electromagnetic Surveying (0.31)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)