Memorial University DAI: Diagenesis and porosity development of paleozoic carbonate and early to mid cretaceous siliciclastic reservoir intervals, Hopedale Basin, Labrador Shelf

advanced search

Digital Archives Initiative
Memorial University - Electronic Theses and Dissertations 4

menu off

add document to favorites : add page to favorites : reference url

back to results : previous : next

Search this object:

0 hit(s) :: previous hit : next hit

View:

previous page : next page

Document Description

Title	Diagenesis and porosity development of paleozoic carbonate and early to mid cretaceous siliciclastic reservoir intervals, Hopedale Basin, Labrador Shelf
Author	Schwartz, Stephen Samuel.
Description	Thesis (M.Sc.)--Memorial University of Newfoundland, 2008. Earth Sciences
Date	2008.
Pagination	xi, 149 leaves : col. ill., col. maps
Subject	Geology, Stratigraphic--Cretaceous; Geology, Stratigraphic--Paleozoic; Hydrocarbon reservoirs--Newfoundland and Labrador--Hopedale Basin; Sandstone--Newfoundland and Labrador--Hopedale Basin; Labrador
Degree	M.Sc.
Degree Grantor	Memorial University of Newfoundland. Dept. of Earth Sciences
Discipline	Earth Sciences
Language	Eng
Spatial Coverage	Atlantic Ocean--Labrador Sea
Notes	Includes bibliographical references (leaves 127-138)
Abstract	Paleozoic carbonates and siliciclastic basins Early to Mid Cretaceous sandstones are observed in the Hopedale and Saglek and represent prerift and synrift sedimentation prior and during the development of the Labrador Shelf, respectively. Both of these sediments have been (and are) of hydrocarbon importance, particularly acting as regional reservoirs, with exploration drilling commencing in the 1970's and ending in the early to mid 1980's. The result was 27 exploration wells and more than 100 000 line km of seismic data acquired from the Canadian side of the Labrador Sea. Hydrocarbons, existing mainly as gas and gas condensates, have been discovered in 5 wells in the Hopedale Basin: Snorri J-90, Hopedale E-33, North Bjarni F-06, Bjarni 0-82, and Gudrid H-55. Reserves are estimated at 4.2 Tcf of natural gas and 123 million barrels of NGL. Play types include both siliciclastic (e.g. North Bjarni) and carbonate reservoirs (e.g. Gudrid H-55). North Bjarni has reserves at 2.2 Tcf of gas and 82 million barrels of NGL. -- The Hopedale Basin carbonates are represented by dolomites and limestones, and were investigated in cores from three exploration wells: Indian Harbour M-52, Gudrid H-55, and Roberval K-92. Core samples from Roberval K-92 (3578 - 3582 m and 3870 - 3873.5 m), Gudrid H-55 (2676 - 2680 m), and Indian Harbour M-52 (3952 - 3958 m) were collected for petrographic investigations and geochemical analyses. Two main types of carbonates are recognized; a wackstone with limited dolomitization (Indian Harbour M-52) and dolostone (Roberval K-92 & Gudrid H-55). Three dolomite phases (Dl, D2 and D3) have been petrographically and geochemically identified and correlated between wells, indicating diagenesis as a result of progressive burial. Trace element and stable isotope geochemistry, along with fluid inclusion data, support petrographic data and aid in the understanding the origin and nature of the dolomitizing fluids. All porosity is recognized as secondary and is a result of several stages of dissolution and dolomitization. However, precipitation of calcite cements has occluded porosity, creating reservoir heterogeneity. 87Sr/86Sr values, sampled from micritic calcite and dolomites, suggest that deposition likely started in the Early to Mid-Ordovician with early dolomitization occurring no later than this time. -- The Bjarni Formation represents the main siliciclastic reservoir on the Labrador Shelf and is composed mainly of fluvial to alluvial sandstones, with interbedded to interlaminated lacustrine shales. Six exploration wells from different stratigraphic depths and locations within the Hopedale Basin, containing approximately 31 m of Bjarni Formation sandstone, were logged, sampled, and petrographically analyzed from intervals that include Bjarni H-81 (2157-2164 m), Ogmund E-72 (2234 - 2240 m), North Bjarni F-06 (2452 - 2458 m), Herjolf M-92 (2632 - 2640 m), Roberval K-92 (3095 - 3112.5 m), and North Leif 1-05 (3110 - 3113.5 m). Petrographic and core analysis have identified compositionally and texturally varied sandstones, ranging from Q90.5F2.0L7.7 to Q38.5F39.0L22.5, that contain diagenetic minerals such as iron oxides (e.g. hematite), chlorite, ferroan and non-ferroan calcite cements, kaolinite, and quartz overgrowths/cements. Both intergranular (initial) and intragranular (secondary) porosities are recognized and are a result of sediment maturity and diagenesis, respectively. Diagenetic minerals are observed occluding mainly intergranular porosity reducing the total porosity, while the intragranular porosity, present in all studied intervals, supplements the total porosity, improving the reservoir quality.
Type	Text
Resource Type	Electronic thesis or dissertation
Format	Image/jpeg; Application/pdf
Source	Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Local Identifier	a2700579
Rights	The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
Collection	Electronic Theses and Dissertations
Scanning Status	Completed
PDF File	(17.04 MB) -- http://collections.mun.ca/PDFs/theses/Schwartz_StephenSamuel.pdf
CONTENTdm file name	45683.cpd