Taming the Thunder Horse With Axes and Vectors

2021 ◽  
Vol 62 (6) ◽  
pp. 630-635
Author(s):  
Bernd Ruehlicke ◽  
◽  
Andras Uhrin ◽  
Zbynek Veselovsky ◽  
Markus Schlaich ◽  
...  
Keyword(s):  
Mass Transport ◽  
Middle Miocene ◽  
Drilling Fluids ◽  
Formation Pressure ◽  
Depositional Settings ◽  
Reservoir Sandstones ◽  
Gravity Driven ◽  
Borehole Image ◽  
Borehole Image Logs

The Thunder Horse Field targets Middle Miocene deepwater turbiditic reservoirs. Despite being prolific, the mapping of the ~180 m thick, partly amalgamated reservoir sandstones is challenging. Seismic quality is reduced by the presence of salt structures. The salt overburden and high formation pressure require the use of heavy mud weights and oil-based drilling fluids, which limit the resolution and interpretation potential of borehole image logs (BHI). Halokinetic movements caused significant post-depositional deformation of the already complex gravity-driven sediment stack, and the reservoir beds drape against an E-W oriented salt wall. Consequently, the assessment and removal of the structural dip component are not trivial, and the evaluation of paleo-transport directions is considerably more complicated compared to undisturbed deepwater reservoirs. This paper illustrates the potential of eigenvector methods to BHI from Ruehlicke et al. (2019) for reconstructing the depositional slope and the architecture of mass transport complexes in the case of chaotic depositional settings and uncertain structural dip. Figures from Henry et al. (2018) are used wherein part axial analysis was performed on data from a group of Thunder Horse wells and presented in more detail.

TAMING THE THUNDER HORSE WITH AXES AND VECTORS

2021 ◽  
Author(s):  
Bernd Ruehlicke ◽  
◽  
Andras Uhrin ◽  
Zbynek Veselovsky ◽  
Markus Schlaich ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Reservoir Characterization ◽  
Drilling Fluids ◽  
Formation Pressure ◽  
Reservoir Sandstones ◽  
Gravity Driven ◽  
Borehole Image ◽  
Borehole Image Logs

The Thunder Horse Field targets Middle Miocene deepwater turbiditic reservoirs. Despite of being prolific, the mapping of the ~180 m thick, partly amalgamated reservoir sandstones is challenging. Seismic quality is reduced by the presence of salt structures. The salt overburden and high formation pressure requires the use of heavy mud weights and oil-based drilling fluids, which limit the resolution and interpretation potential of borehole image logs (BHI). Halokinetic movements caused significant post-depositional deformation of the already complex gravity- driven sediment stack and the reservoir beds drape against an E–W oriented salt wall. Consequently, the assessment and removal of the structural dip component is not trivial and the evaluation of paleo-transport directions is considerably more complicated compared to undisturbed deepwater reservoirs. The intention of this paper is to bring the main results from Henry et al. (2018) into context with the eigenvector methodology from Ruehlicke et al. (2019) and to emphasize its value for reservoir characterization.

Direct TOC Quantification in unconventional Kerogen-rich Shale Resource Play from Elemental Spectroscopy Measurements: A Case Study from North Kuwait

2015 ◽  
Author(s):  
Girija K. Joshi ◽  
Mihira N. Acharya ◽  
Marie Van Steene ◽  
Sandeep Chakravorty ◽  
Christophe Darous ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Gamma Ray ◽  
Horizontal Wells ◽  
Final Analysis ◽  
Total Carbon ◽  
Empirical Estimation ◽  
New Type ◽  
Borehole Image ◽  
Borehole Image Logs

Abstract The deep organic-rich calcareous Kerogen of North Kuwait, a continuous 50ft thinly alternating carbonate – organic-rich argillaceous sequence, is not only a source rock but has gained importance as potential reservoirs themselves of typical unconventional category. Resource play or Kerogen characterization relies on quantifying total organic carbon (TOC) and estimating accurate mineralogy. This paper describes the first attempt to directly measure total organic carbon of the Limestone-Kerogen sequence. For the present study, empirical estimations of TOC have been carried out based on conventional log measurements and nuclear magnetic resonance (NMR). The introduction of a new neutron-induced capture and inelastic gamma ray spectroscopy tool using a very high-resolution scintillator and a new type of pulsed neutron generator for the deep unconventional kerogen resources have provided a unique opportunity to measure a stand-alone quantitative TOC value using a combination of capture and inelastic gamma ray spectra. In this process, Inorganic Carbon Content (ICC) is estimated by using elemental concentrations measured by this logging tool in addition to measuring Total Carbon, and this value is subtracted from the measured total carbon to give TOC. The advanced elemental spectroscopy tool measurements were first used to determine accurately the complex mineralogy of the layered carbonate and organic-rich shale sequence. Extensive laboratory measurements of core / cuttings data were used to calibrate the petrophysical evaluation and capture the heterogeneity seen on borehole image logs. The final analysis shows considerable improvements compared to conventional empirical estimation. Once the mineralogy is properly determined, the log-derived TOC matches very well with core measured TOC. This technique has provided a new direct and accurate log-derived TOC for Kerogen characterization. The application has a potential to be used for CAPEX optimization of the coring in future wells. This technique can also be applied in HPHT and High-angle horizontal wells, which can overcome challenging coring difficulties in horizontal wells.

scholarly journals Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge, Danish North Sea

2011 ◽  
Vol 25 ◽  
pp. 1-60 ◽  
Author(s):  
Kresten Anderskouv ◽  
Finn Surlyk
Keyword(s):  
Mass Transport ◽  
Shear Deformation ◽  
North Sea ◽  
Debris Flows ◽  
Upper Cretaceous ◽  
Transport Processes ◽  
High Concentration ◽  
Energy Flows ◽  
Common Precursor ◽  
Gravity Driven

The 331 m long core from the Mona-1 well in the Danish North Sea spans almost the entire Upper Cretaceous Chalk Group but only about 10% of Late Cretaceous time is represented. The succession comprises 14 facies representing pelagic deposition, turbidity flow, and mass-transport processes, including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or absence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites, and the resultant deposits were thoroughly bioturbated if deposited during normal oxygenation at the sea floor. Periodic benthic dysoxia resulted in the preservation of primary structures, as represented by laminated chalk which consists of thin pelagic laminae alternating with thin turbidites. In addition to the thin turbidites in the laminated chalk, four different turbidite facies are interpreted as representing high- to low-energy flows. Clast-supported chalk conglomerates have previously not been differentiated from other turbidites, but are here interpreted to be directly related to the down-slope evolution of debris flows. Debris flows are represented by matrix-supported conglomerates, which form one of the most common facies in the succession. High-concentration, gravity-driven suspension flows passed into dilute visco-plastic flows during the final stages of deposition and resulted in the deposition of structureless chalks. Limited shear deformation produced distinct quasi-facies from which the precursor facies can be deduced, whereas intense or continued shear deformation produced a shear-banded quasi-facies from which the precursor facies cannot be deduced in all cases. A series of major slump packages (14–18 in total) are interpreted, forming over 40% of the succession; debrites appear to be the most common precursor facies involved in slumping. The vertical succession of facies records an earliest Cenomanian facies shift from dominantly siliciclastic to chalk deposition. The Cenomanian – late Campanian period was dominated by erosion or sediment by-pass with minor associated mass-transport deposits preserved. Basin filling by pelagites and turbidites prevailed in the late Campanian, whereas Maastrichtian pelagic deposition was interrupted by increasingly frequent and voluminous mass-transport events.

scholarly journals The Use of Borehole Imaging Logs to Optimize Horizontal Well Completions in Fractured Water-flooded Carbonate Reservoirs

GeoArabia ◽  
1997 ◽  
Vol 2 (1) ◽  
pp. 19-34
Author(s):  
Rashid Al-Busaidi
Keyword(s):  
High Water ◽  
Carbonate Reservoirs ◽  
Production Performance ◽  
Seismic Resolution ◽  
Fractured Zones ◽  
Fracture Systems ◽  
Water Breakthrough ◽  
Borehole Image ◽  
Borehole Image Logs

ABSTRACT Early water breakthrough has occurred in the Lower Cretaceous carbonate reservoirs (Aptian Shu’aiba Formation) in Yibal and Lekhwair fields, north Oman. Borehole Image logs were run in more than 10 horizontal wells in each field to investigate the role of faults and fracture systems, as well as facies variations and sedimentary features. These logs indicated the presence of highly-fractured zones with both open and cemented fractures. The fractures have orientations consistent with fault patterns interpreted from 3-D seismic data. High density fractured zones, in most cases, correspond to faults, some of which are below seismic resolution. The presence of fractures and/or fracture zones is the primary cause of early water breakthrough. Improved production performance was achieved by perforating non-fractured intervals to avoid early high water cuts.

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