«By © Nicola S. Tonkin A thesis submitted to the Schoo l of Graduate Studies in partial fulfillm ent of the requir ements for the degree of Doctor of ...»
RESERVOIR QUALITY AND
LATERAL VARIABILITY OF
BIOTURBATED SHALLOW MARI NE
© Nicola S. Tonkin
A thesis submitted to the
Schoo l of Graduate Studies
in partial fulfillm ent of the
requir ements for the degree of
Doctor of Philosophy
Department of Earth Sc iences
Memorial Univers ity of Newfoundland
In bioturbated reservoir facies, ichnolog is integral toreservoircharac terization.
y Ichnological analysis ofa reservoir facies and subsequent c1assification into ichnofabrics or ichnofacies allows for characterization of reservoir properties. Bioturbation can redistribute grains and cause sorting or mixing, this physical modification ofth eprimary sedimentary fabric causes changes to porosity, and permeability in reservoir facies. In highly bioturbated reservoir facies, bioturb ation can be the first order control on petrophysical properties.
Petroleum geologists are primarily concemed with the effect that bioturbationhas on the petrophysical properties of a reservo ir facies, rather than the details of ichnotaxonomicidentification. The proposed bioturbation style categories do not require in-depth knowledge of ichnology. The categories can easily be applied to facies and core analysis for incorporation into reservoir models. The action ofbioturbators can be considered in terms of: I) sed iment mixing; 2) sediment cleaning; 3) sediment packing; 4) pipe-work buildin g strategies; 5) combination sediment cleaning and packing; and 6) combination pipe-work buildin g and sediment packing. Sedim ent packing and sed iment mixing sty les commonly reduce porosity/permeability, while sediment cleaning bioturbation style enhancesporosity/permeability. Pipe-work buildin g and combinatio n bioturbation styles are highly dependent on the lithological contrastbetween burrow fill, and enclos ing substrate. The use of bioturbation style categories, and the classification of trace fossils into these categories may be more user-friendly for reservoir geologists than existing paleoenvironmentally-driven ichnofacies or ichnofabric analysis.
While categorization of bioturbat ion style is a useful tool in reservoir charac terization, lateral variations in reservoir quality and heterogeneity of ichnofac ies or ichnofabric must be incorporated into geological models in orderto predict fluid flow in bioturbated facies at the inter-well scale. Ichnological analysis allows insight into variations in sedimentation rate, hydrodynamic energy (erosive currents), substrate consistency, length of colonization window, and community success ion (tiering and cross-cutting relationships). This ichnological dataset means that inferences rega rding both physica l and chemical processes acting at the time ofbioturbation can be made.
There is inherent ichnological varia bility within most bioturbated beds. The lateral variabi lity,o r patchiness of the ichnofabrics studied were not found to be related to proximity to the paleo-shoreline in the three wave -dominated depositiona l systems.
Instead, the most critical factor appears to be the sediment accumulation sty le. Slow continuous depos ition was found to produce complex and highly patchy ichnofabrics, whereas rapid,e pisodic, event bed deposition was found to be associated with the most uniform deve lopment of ichnofabric.
Autocy lic and allocyclic interpre tations can be postulated for bioturbated key stratigraphic surfaces in siliciclastic shallow marine settings. A case study illustrating the need for careful ichnological analysis has been undertake n as partofthis thesis, and focuses on Thalassino ides, and its validity as an indicator for key stra tigraphic surfaces.
Thalassino ides iseas ilyide ntified incoreando utcrop, hasa pipe-workbioturbationstyle, and colonizes a variety of substrates including softground and firmgroun d (Glossifimgit es ichnofacies) substrates. The Glossifungites ichnofacies is commonly found in association with relative sea level change, but alternative autocy clica lly-generated processes should be considered. With careful ichnological investigation, realisticp alaeoenvironmental and sequence stratigraph ic interpretations can be made by object ive considera tion of both autocyclic and allocyclic processes.
understand ing of likely reservoir quality, reservoir heteroge neity,and interpretation of candida te key seque nce stratigra phic surfaces. These concepts are an integra l part of reservoir to basin scale models of hydrocarbon reservoirs. With an improved, integrated, understanding of whatbioturbating organismsdo to sediment,i chnology can continue to grow as an important component of reservo ir character ization studies, and petroleu m geology in general.
Acknowledgments Two children, one husband now a PhD submitted since arriving in Newfo undland to start my PhD in 2006, what a jo urney ! First up, I would like to thank my wonderful husband for his enduring love and support, I love you, and your name should be on this thesis with mine. To my gorgeous boys Eddie and Lachlan, for always making me smile.
Mum and Dad, thank you for your constant positivity, optimism, and far-reaching love.
Hope, Lorne, Shawna, Janis and Carl thanks for all your love and support.
Thanks to the 6th floor crew; Chris, Liam, James, Pinar, Rich, Jen, Dario, Kathryn, Lise, Peter and Lina for your friendship, banter, babysitting, and good times. To Karen, Anna, and all my "Mummy" friends for keeping me sane while wra ngling the midgets. Amy, Allison, Steve, Angie, Erin, Brian, Vic, Paul, Venessa, and Twy la thanks for your friendship, and always making me feel at home in St John 's. Chris (Xtal), thank you for always listening, bitching with me, partying, and making me gourmet delights when I need it most. Thanks to the NZ "g irls" for your never-endin g, web-ass isted support and love. Thank you to Kathy Campbell and Murray Gregory for giving me a solid foundation to build upon. Thank you to everyone, who I have forgotten to menti on (my brain capacity has been exceeded today).
Thank you to Rudi Meyer, Elliot Burden, and my committee members Joe Macquaker and Rich Callow for your support. To my supervisor and friend Duncan McIlroy, thank you for your guidance, support, and for putting up with my double maternity leave!
Table of Contents
Chapter 2 - Bioturbation influence on reservoir quality: a case study from the Cretaceous Ben Nevis Formation, Jeanne d'Arc Basin, offshore r-.
Ta ble t.1 Bioturbation Index (BI).
Table 2.1 Ben Nevis L55 core interval summary.
T able 3.1 Bioturbation style categories in marine sediments (after Tonkin et al.
, 20 10).
Table 4.1 Table of modern analogues of the Thalassinoides tracemaker Table 4.
2 Thalassinoides occurrence in ancient and modern siliciclastic and carbonate environments.
Bioturbation style categories in marine sediments (modified and updated from Tonkin etal., 2010).
List of Figures
Figure 1.1 Environmental controls on trace fossil production Figure 1.
2 Controls and attributes on the formation of an ichnofabric Figur e 1.3 Ichnofabric Constituent Diagrams (lC D) Figure1.4 Distribution of archetypal ichnofacies in the marine realm Figure1.5 Coastal classification of major clastic coastal depositional environments Figure 1.6 Large thin slicing technique Figure 1.7 Spot permeability measurements of core slab Figure 2.1 Sedimentary basins of the Grand banks, offshore Newfoundland, Canada Figure 2.2 Ben Nevis L-55 lithofacies photographs.
Figure 2.3 Porosity and petrography lithofacies I (LF I), Ben Nevis L-55 core interval.
Figure 2.4 Porosity and petrography lithofacies 4 (LF4), Ben Nevis L-55 core interval.
Largeth ins licea nd permeability datao fsa mples l,2and3.
Figure 2.5 Figure 2.
6 Large thin slice and permeability data of samples 4 and 5.
Figur e 3.1 Quaternary proximal fan delta plain facies, Conway Flats, NZ.
Figur e 3.2 Lateral profile photographs from proximal fan delta plain facies.
Figure 3.3 Lateral profile of Conway Flats, data summary.
Figure 3.4 Late Cretaceous shoreface succession, Neslen Formation, Book Cliffs, Utah.
Figure 3.5 Lateral profile photographs from shoreface facies.
Figure 3.6 Lateral profileofNes len Formation, data summary.
Figure 3.7 Late Miocene shelfal succession, Pohutu Formation, RaukumaraP eninsula, NZ Figure 3.
8 Lateral profile photographs from shelf facies.
Figure 3.9 Lateral profile of Pohutu Formation, data summary.
Figure 4.1 Summary of environmental parameters and auto/allocyclic contro ls.
Figure 4.2 Taphonomy of Thalassinoides burrows.
Figure 4.3 Four taphonomic expre ssions of Thalassinoides inmarinesiliciclastic shallow marine environments.
Fig ure 4.4 Schematic interpretation of the creation of sand-filled Thalossinoides in mudstone ("G lossifun gites surfaces").
Figure 4.5 Examples of Thalossin oides-bearing stratigraphic surfa ces Co-a uthors hip State ment The followin g chapters are presented in manuscript format.
Each chapter/manuscript has already been, or will be, submitted to an internation al scientific journal. Consequently, these works have involved collaboration with other authors. I shall describe below the work personally done and contributions made by my co-authors. In each case the work is predominantly my own, completed with collaboration, guidance and editorial advice from my supervisor and co-author Duncan McIlroy, and other junior collaborators.
The first manuscript (Chapter 2, Tonk in et al., 20 10) is a core-based study. Corelogging was undert aken by me in May 2008 at CNLOPB core storage. Core slabs had been previously collected by my co-authors Rudi Meyer and Allison Turpin. Rudi Meyer trained me in use of the probe permeameter and provided guidance in this area.
Permeability measurement s and visual estimati on of porosity were undert aken by me.
Blue-epoxy impregn ated thin sections were prepared by Calgary Rock Sales. I am the primary author on the manuscript with my supervisor Duncan McIlroy and co-author Rudi Meyer providing guidance and constructive editori al comment s. Thi s work was funded by an NSERC Discovery Grant and an NSERC/PRA C CRD Grant to Duncan McIlro y, with supplementary funding from the Pan-At lantic Petrol eum Systems The second case-studybasedmanuscript(Chapter 3),in volveddata co llectedfrom 3 outcrop localities. Field seasons in Argenti na, New Zealand and Utah were completed in 2006. All data was collected by me (logs and sampling), with rock-saw assistance from Duncan McIlroy. CT scanning was done by Chris Phillips. Preparation of large thin slices was done by Chris Phillips and Leon Normore. Blue-epoxy impregnated thin sections were prepared by Calgary Rock Sales, and standard thins ection s provided by the technic ians at MUN. Duncan McIlroy provided expert know ledge, guidance, and editorial comments during construction of the manuscript. Funding came from a NSERC Discovery Grant to Duncan McIlroy.
The third manuscript (Chapter 4) is a conceptual study, with examples from outcrop and core-ba sed study of Thalassinoides burrows collected throughout my PhD.
Specimens were observe d and/or collected by me from offshore Newfou ndland (core slab), New Zealand (slab sample and observation), Argentina (observa tions), and Utah (observations). All images logs, images were personally acquired. Duncan Mcilroy provided guidance and constructive editoria l comme nts. Funding came from the NSE RC Discovery Gran t to Duncan Mcilroy.
Cha pte r I: Introduction Man y of the wor ld' s siliciclastic reservoirs are de ve loped in biotu rbated shallow marine facies incl uding Jeann e d' Arc Basin, offshore Newfoundland, Canada;
No rth Sea, UK; Halten Terrace, olTshore mid-Norw ay; Athaba sca O il Sands, Canada;
and Orin oco Oil Belt, Venezuel a (McA lpine, 1990; Richard s, 1992 ; Cannon and Gow land, 1996; Mcil roy, 2004b; Crerar and Amott, 2007; Labourdette et al., 2008 ) Bioturbation can redistr ibute grains and resuit in either sorting or mixing ; this phy sical modification of the primary sedimentary fabric affect s porosity an d permeab ility in reserv oir fac ies. Effective produ ction o f hyd rocarbon reservoirs requ ires reliable prediction o f facies-r elated reserv oir propert ies and co rrelation at the inter-well sca le.
In biotur bated facies, paleoenvironmental analysis and reservoir characterization are heavily reliant upon the desc ription and interpretation o f ichnofabries (e.g., Martin and Poil ard, 1996; Pemb erton et ol.,200 1;Mcilroy, 2004b ;P emb ert on and Gingras, 2005 ;
In this thesis, outcrop and core-based case studies are used toproduce afi rst orde r understan ding of : I) the effect of bioturbation on reservoi rquality;2)latera l ichno log ieal va riability; and3) the interpre tatio no f "Gl oss ifulJgites surfaces" that may be incor porat ed into paleoen vironmental and reservo ir models o f siliciclastic shallow marin e hydro carb on reserv oirs.
1.1 Aim a nd Scope T his research generates a more co mplete understand ing of the impact that bioturbat ion has on reservoir quality and characte rization o f shallow marin e success ions. Bioturb ated siliciclastic strata are studied : I) at the micro-fabric sca le; 2) the outcro p sca le; and 3) in term s of sequence stratigraphic cycl es. T he aim at the micro- fabri c scale is to understand the role that organisms have in co ntro lling the poro sity and perm eab ility of sandstone reservoir interva ls. Along-strik e or lateral trend s in sedimentological and ichnological variability are studied at the outcrop scale.