Important geological properties of unconventional resource shales

2011 ◽  
Vol 3 (4) ◽  
Author(s):  
Roger Slatt
Keyword(s):  
Shale Gas ◽  
Environmental Changes ◽  
Rock Properties ◽  
Type I ◽  
Shale Oil ◽  
Hydrocarbon Production ◽  
General Sequence ◽  
Geomechanical Properties ◽  
Depositional Processes ◽  
Stratigraphic Model

AbstractThe revelation of vast global quantities of potentially productive gas and oil-prone shales has led to advancements in understanding important geological properties which impact reservoir performance. Based upon research on a variety of shales, several geological properties have been recognized as being common and important to hydrocarbon production. (1) transport/depositional processes include hemipelagic ‘rain’, hyperpycnal flows, turbidity current flows, tempestites, wave-reworking, and contour currents in both shallow and deep water settings. (2) Common shale minerals include clays, quartz, calcite, dolomite, apatite, and pyrite; organic constituents include spores (Tasmanites), plant remains, biogenic quartz and calcite, and arenaceous foraminifera. (3) Porosity and permeability are characteristically low with pore sizes ranging down to the nanoscale. Main pore types include intergranular (including pores within clay floccules), porous organic matter, porous fecal pellets, and microfractures. (4) Important geochemical characteristics include organic richness (>3%), maturity (>1.1%Ro for shale gas and 0.6–0.9% for shale oil) and type (I–IV), in addition to certain biomarkers which are indicators of bottom water oxicity during deposition. Remaining hydrocarbon potential [RHP = (S1 + S2)/TOC] also reflects temporal environmental changes. ‘Isotopic reversals’ can be used to detect best producing areas in shale-gas plays. (5) Lithofacies stacking patterns and sequence stratigraphy are the result of eustatic depositional history. A general sequence stratigraphic model is presented here that highlights this commonality. (6) Geomechanical properties are key to drilling, fracturing and production of hydrocarbons. Brittle-ductile couplets at several scales occur in shale sequences. (7) Geophysical properties, when calibrated to rock properties, provide a means of regionally to locally mapping the aforementioned properties. (8) Economic and societal considerations in the exploration and development of resource shales are garnering attention. Many potentially economic shale-gas and shale-oil plays are being identified globally. Risks and uncertainties associated with gas- and oil-rich shales include the lack of long-term production histories, environmental concerns related to hydraulic fracturing, uncertainty in calculating hydrocarbons-in-place, and fluctuations in supply, demand, and price.

scholarly journals Shale Oil/Gas: A New Opportunity for New Zealand?

2021 ◽  
Author(s):  
◽  
Raul Correa Rechden Filho
Keyword(s):  
New Zealand ◽  
Shale Gas ◽  
Oil And Gas ◽  
East Coast ◽  
Unconventional Reservoirs ◽  
Field Size ◽  
Brittleness Index ◽  
Rock Properties ◽  
Shale Oil ◽  
Geochemical Analyses

<p>Within New Zealand the East Coast Basin encompasses the primary shale oil and gás (unconventional) play areas in which both the Waipawa and Whangai formations are widespread. These formations are oil and gas prone and prevalent throughout a large area of the East Coast Basin. To characterise these two formations and evaluate their shale oil and gas potential, existing analytical results were supplemented by a set of new sample analyses of organic and inorganic geochemistry, and rock properties. Thus, some 242 samples from the Whangai Formation have organic geochemical analyses and 40 have inorganic geochemical analyses; for the Waipawa Formation there are 149 organic and 9 inorganic geochemical analyses. In addition, downhole logs from three exploration wells have been used to calculate the brittleness index of the Whangai Formation. All these data have been grouped by structural block and used to determine where the sweet spots are in each formation. Both basic and more robust statistical analysis (machine-learning) is applied to identify the best prospective area. The Rakauroa Member (Whangai Formation) and the Waipawa Formation have the best rock characteristics as unconventional reservoirs, based on quantity and quality. Maturation appears to be an issue for these formations, although there are some localised areas where the Whangai Formation has better maturity. The brittleness index is calculated only for the Rakauroa Member, given the lack of data available for other members of the Whangai Formation and the Waipawa Formation, and yielded promising results. The Motu block appears to be the best area in which to explore for unconventional oil and gas. The prospective resource volumes for the best case scenario for the Whangai (Rakauroa Member) and Waipawa formations combined in the Motu Block are 17% higher (713MMbbl) than the 2P (proved + probable) reserves of New Zealand for oil and condensate (588MMbbl) and 26% (2.1TCF) of the 2P (proved + probable) reserves of natural gas (7.8 TCF). Economic analysis shows feasibility to explore these unconventional reservoirs for both shale oil or shale gas with an oil price of US$60 for both methodologies tested. However, the methodology applied using standard shale oil and gas assessments shows feasibility only for shale oil. Shale gas would not be economic, unless a higher oil prices, lower costs or a technology was developed to improve the recovery factor of these reservoirs. These results indicate a minimum economic field size of 4.5 km² for this area.</p>

scholarly journals Shale Oil/Gas: A New Opportunity for New Zealand?

2021 ◽  
Author(s):  
◽  
Raul Correa Rechden Filho
Keyword(s):  
New Zealand ◽  
Shale Gas ◽  
Oil And Gas ◽  
East Coast ◽  
Unconventional Reservoirs ◽  
Field Size ◽  
Brittleness Index ◽  
Rock Properties ◽  
Shale Oil ◽  
Geochemical Analyses

<p>Within New Zealand the East Coast Basin encompasses the primary shale oil and gás (unconventional) play areas in which both the Waipawa and Whangai formations are widespread. These formations are oil and gas prone and prevalent throughout a large area of the East Coast Basin. To characterise these two formations and evaluate their shale oil and gas potential, existing analytical results were supplemented by a set of new sample analyses of organic and inorganic geochemistry, and rock properties. Thus, some 242 samples from the Whangai Formation have organic geochemical analyses and 40 have inorganic geochemical analyses; for the Waipawa Formation there are 149 organic and 9 inorganic geochemical analyses. In addition, downhole logs from three exploration wells have been used to calculate the brittleness index of the Whangai Formation. All these data have been grouped by structural block and used to determine where the sweet spots are in each formation. Both basic and more robust statistical analysis (machine-learning) is applied to identify the best prospective area. The Rakauroa Member (Whangai Formation) and the Waipawa Formation have the best rock characteristics as unconventional reservoirs, based on quantity and quality. Maturation appears to be an issue for these formations, although there are some localised areas where the Whangai Formation has better maturity. The brittleness index is calculated only for the Rakauroa Member, given the lack of data available for other members of the Whangai Formation and the Waipawa Formation, and yielded promising results. The Motu block appears to be the best area in which to explore for unconventional oil and gas. The prospective resource volumes for the best case scenario for the Whangai (Rakauroa Member) and Waipawa formations combined in the Motu Block are 17% higher (713MMbbl) than the 2P (proved + probable) reserves of New Zealand for oil and condensate (588MMbbl) and 26% (2.1TCF) of the 2P (proved + probable) reserves of natural gas (7.8 TCF). Economic analysis shows feasibility to explore these unconventional reservoirs for both shale oil or shale gas with an oil price of US$60 for both methodologies tested. However, the methodology applied using standard shale oil and gas assessments shows feasibility only for shale oil. Shale gas would not be economic, unless a higher oil prices, lower costs or a technology was developed to improve the recovery factor of these reservoirs. These results indicate a minimum economic field size of 4.5 km² for this area.</p>

Anisotropic Geomechanical Rock Properties Modelling for Unconventional Shale Gas Formation

2021 ◽  
Author(s):  
Ikhwanul Hafizi Musa ◽  
Chee Phuat Tan ◽  
Junghun Leem ◽  
Iftikhar Altaf ◽  
Zahidah Md Zain ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Shale Gas ◽  
Velocity Shear ◽  
Rock Properties ◽  
Triaxial Tests ◽  
Sonic Velocity ◽  
Confining Stress ◽  
Geomechanical Properties ◽  
Core Samples ◽  
Using Data

Abstract Geomechanical rock properties correlations and modeling approach for conventional reservoirs are inappropriate and unsuitable for unconventional shale gas reservoirs where the shale formation is strong and has very low porosity. These correlations are critical in the development of 1D and 3D geomechanical models which are used for various field applications including drilling optimization, hydraulic fracturing design and operation, and field management. The study investigates various geomechanical rock properties and their relationships to one another using data extracted from rock mechanics testing conducted on shale core samples. For rock elastic properties correlations, dynamic elastic properties determined from compressional sonic velocity, shear sonic velocity and density are plotted against laboratory-measured static elastic properties obtained from triaxial tests. Steps were taken to further refine the properties correlations by separating the data from vertical and horizontal core samples, using data from tests conducted at in-situ confining stress condition, and focusing on data only taken from Field A and nearby fields. Similar steps were also taken to develop the correlations for rock strength properties. Correlations for the shale anisotropic elastic properties were also developed based on ratio of horizontal and vertical elastic properties. Blind tests were conducted on three wells in Field A using the new rock properties correlations which showed good matching of the predicted geomechanical properties with the new correlations and core measured test data.

scholarly journals Cellular stress signaling activates type-I IFN response through FOXO3-regulated lamin posttranslational modification

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Inah Hwang ◽  
Hiroki Uchida ◽  
Ziwei Dai ◽  
Fei Li ◽  
Teresa Sanchez ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Environmental Changes ◽  
Type I ◽  
Neurogenic Differentiation ◽  
Forkhead Box ◽  
Nuclear Lamin ◽  
Neural Stem Progenitor Cells ◽  
Subsequent Activation ◽  
Methyl Group Transfer

AbstractNeural stem/progenitor cells (NSPCs) persist over the lifespan while encountering constant challenges from age or injury related brain environmental changes like elevated oxidative stress. But how oxidative stress regulates NSPC and its neurogenic differentiation is less clear. Here we report that acutely elevated cellular oxidative stress in NSPCs modulates neurogenic differentiation through induction of Forkhead box protein O3 (FOXO3)-mediated cGAS/STING and type I interferon (IFN-I) responses. We show that oxidative stress activates FOXO3 and its transcriptional target glycine-N-methyltransferase (GNMT) whose upregulation triggers depletion of s-adenosylmethionine (SAM), a key co-substrate involved in methyl group transfer reactions. Mechanistically, we demonstrate that reduced intracellular SAM availability disrupts carboxymethylation and maturation of nuclear lamin, which induce cytosolic release of chromatin fragments and subsequent activation of the cGAS/STING-IFN-I cascade to suppress neurogenic differentiation. Together, our findings suggest the FOXO3-GNMT/SAM-lamin-cGAS/STING-IFN-I signaling cascade as a critical stress response program that regulates long-term regenerative potential.

scholarly journals THE MAIN RESERVE OF ACCELERATED EFFECTIVE OPENING OF OIL AND GAS FIELDS IN UKRAINE

2019 ◽  
pp. 31-37
Author(s):  
V. T. Kryvosheyev ◽  
V. V. Makogon ◽  
Ye. Z. Ivanova
Keyword(s):  
Shale Gas ◽  
Oil And Gas ◽  
Research Work ◽  
Oil And Gas Industry ◽  
The United States ◽  
Resource Base ◽  
Hydrocarbon Production ◽  
Oil And Gas Fields ◽  
High Level ◽  
Gas Fields

Economic hardship in Ukraine during the years of independence led to a sharp reduction of exploration work on oil and gas, a drop in hydrocarbon production, a decrease in inventories and a sharp collapse of research work to ensure the growth of hydrocarbon reserves.The hydrocarbon potential of various sources of Ukrainian subsoil is quite powerful and can provide future energy independence of the country. Potential hydrocarbon resources in traditional traps of various types are exhausted by only 25 %. Ukraine has recently experienced so-called “shale gas boom”. The experience of extraction of shale gas in desert areas of the United States can not be repeated in densely populated Ukraine in the absence of such powerful shale strata, resource base, necessary infrastructure, own technologies and techniques and economic, environmental and social risks.Taking into account the fuel and energy problems of the state, we constantly throughout the years of independence oriented the oil and gas industry and the authorities on the active use of our own reserves and opportunities for accelerated opening of new oil and gas fields.The results of geological exploration work in the old oil and gas basins at the high level of their study indicate that deposits in non-structural traps dominate among open deposits.A complex of sequence-stratigraphical, lithology-facies and lithology-paleogeographical studies is being successfully used to forecast undeformational traps in well-studied oil and gas bearing basin of the Ukraine – the Dniprovsko-Donetsky basin. The authors predict wide development of stratigraphic, lithologic, tectonic and combined traps in terrigenous sediments of Tournaisian and Visean age, reef-carbonate massifs of the lower Tournaisian, lower and middle Visean age and others. They should become the basis for exploration of oil and gas fields for the near and medium term and open the second breath of the basin.

scholarly journals Assessment of potential shale gas and shale oil resources of the Norte Basin, Uruguay, 2011

Fact Sheet ◽  
2011 ◽  
Author(s):  
Christopher J. Schenk ◽  
Mark A. Kirschbaum ◽  
Ronald R. Charpentier ◽  
Troy Cook ◽  
Timothy R. Klett ◽  
...  
Keyword(s):  
Shale Gas ◽  
Shale Oil ◽  
Oil Resources

From shale oil to biogenic shale gas: retracing organic-inorganic interactions in the Alum Shale (Furongian-Lower Ordovician) in southern Sweden

AAPG Bulletin ◽  
2015 ◽  
Vol 99 (05) ◽  
pp. 927-956 ◽  
Author(s):  
Hans-Martin Schulz ◽  
Steffen Biermann ◽  
Wolfgang van Berk ◽  
Martin Krüger ◽  
Nontje Straaten ◽  
...  
Keyword(s):  
Shale Gas ◽  
Shale Oil ◽  
Southern Sweden ◽  
Alum Shale ◽  
Lower Ordovician
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