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Search and Discovery Article

Relative permeability in shales is an important petrophysical parameter for purposes of accurate estimation of production rate and recovery factor, efficient secondary recovery, and effective water management. We present a method to estimate saturation-dependent relative permeability in shales based on the interpretation of the low-pressure nitrogen adsorption-desorption isotherm measurements. Relative permeability were determined for 30 samples from the gas — and oil — window of Eagle Ford and Wolfcamp shale formations. These sample have low-pressure helium porosity (LPHP) in the range of 0.04 to 0.09 and total organic content (TOC) in the range of 0.02 to 0.06. The samples were ashed to study the effects of removal of organic matter on the pore size distribution, pore connectivity, and relative permeability. The estimated irreducible water saturation and residual hydrocarbon saturation are directly proportional to the TOC and LPHP, and exhibit 15% variation over the entire range. Pore connectivity, in terms of average coordination number, decreases by 33% with the increase in TOC from 0.02 to 0.06. The estimated fractal dimension is close to 2.7 for all the samples. The estimated relative permeability of aqueous phase and that of hydrocarbon phase at a given saturation is inversely proportional to the TOC. Relative permeability curves of the hydrocarbon phase for geological samples from various depths in a 100-feet interval indicate that the hydrocarbon production rate will vary drastically over the entire interval and these variations will increase as the hydrocarbon saturations reduce in the formation. In contrast, relative permeability curves of the aqueous phase suggest limited variation in water production rate over the entire interval. Further, based on the relative permeability curves, the hydrocarbon production is predicted to be negligible for hydrocarbon saturations below 50% and the water production is expected to be negligible for water saturations below than 80%. Efforts are ongoing to use the laboratory-based estimates to predict field-scale production and recovery rates.

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American Association of Petroleum Geologists (AAPG)
Search and Discovery Article

Measurements of fluid wetting characteristic are made routinely on rock samples. However, there are no published petrophysical models to differentiate between oil-wet and water-wet fractions of a reservoir sequence using commonly available log suites. This presentation builds on our previous publication that describes the unconventional reservoir petrophysical model we have developed (Holmes, 2014). Essentially, we define four porosity components, namely total organic carbon, clay porosity, effective porosity, and “free shale porosity.” This last component is an indirect calculation if the first three components do not sum to total porosity.  Porosity/resistivity plots can be constructed for the total porosity and interpreted in a standard fashion. These will mostly indicate a water-wet system where the effective porosity fraction is examined. A second porosity/resistivity plot compares resistivity with “free shale porosity,” and is clearly interpreted to indicate Archie saturation exponents of much larger than 2 — frequently in excess of 3 — indicating the oil-wet fraction of the reservoir system. Additionally, the plots suggest low to very low values of cementation exponent, ranging from 1.0 to 1.5.   Examples from the Bakken of Montana and North Dakota, the Niobrara of Colorado, and the Wolfcamp and Spraberry of Texas are presented showing quantitative distinction of water-wet vs. oil-wet reservoir components.

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American Association of Petroleum Geologists (AAPG)
Search and Discovery Article

Interpretations of thermal maturation provide critical data needed for both conventional and unconventional resource assessments. The absence of true vitrinite in pre-Devonian sediments eliminates one of the most commonly measured geothermometers used for thermal maturity determination. Programmed pyrolysis parameters like Tmax can be of limited utility given the maturity regime. However, other organic macerals are potentially available to constrain thermal maturity. The current organic petrology study has been undertaken to provide a very detailed comparison of reflectance measurements on pyrobitumens, “vitrinite-like” material and graptolites.  In the Appalachian Basin of North America, Cambrian-aged source rocks were deposited in shallow water mixed carbonate-siliciclastic depositional environments. Solid pyrobitumen material is found to occur in both lenticular lens/layer morphology as well as distinct pore-filling angular varieties. Published formulas to calculate Equivalent Reflectance (Eq. Ro) from solid bitumens have been applied to these discrete morphological populations. In addition, a newly developed formula to calculate Eq. Ro from angular pyrobitumen (VRc=0.866*BRo ang + 0.0274) is introduced based upon statistical evaluation of reflectance readings from a global dataset. “Vitrinite-like” organic macerals were found in rare abundance within these potential source rocks, but their occurrence enables an independent comparison to pyrobitumen Eq. Ro values. Graptolites are another organic maceral that can be evaluated via organic petrology, but caution should be utilized since these tend to show a high degree of anisotropy. The results of this investigation provide additional geochemical guidance to assist geologists in more accurately interpreting thermal maturity in the Rome Trough region of the Appalachian Basin.

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American Association of Petroleum Geologists (AAPG)
Search and Discovery Article

Rock-Eval hydrogen index (HI) is often used to compare relative maturities of a source horizon across a basin. Usually, there are several measurements from the source horizon at a single well, and the mean hydrogen index is calculated, or the S2 is plotted against TOC. The slope of the best fit line through that data is used as the representative HI for that well (sometimes referred to as the ‘slope HI ’ methodology). There is a potential flaw in both these methodologies; however, that renders the calculated HI as misleading if the source horizon being examined is not relatively uniform in source quality, vertically in the stratigraphic column. From a geologic perspective, it would be unusual for the source rock quality not to vary vertically in the stratigraphic column. Organic matter input, preservation, dilution, and sediment accumulation rate typically vary in many depositional environments over the millions of years required to create a thick source rock package. Nevertheless, there are source rocks which do display remarkable source-quality uniformity from top to bottom of the stratigraphic package. We have examined source rocks from several basins where the source quality is relatively uniform over the stratigraphic column, and source rocks where the source quality varies greatly over the stratigraphic column. Methodologies to assess hydrogen index at specific wells for the se two scenarios differ. Most geoscientists may not be familiar with why a single technique is not suitable for both these scenarios, or how to correctly use hydrogen index as a relative maturation proxy in the case where source rock quality is not uniform. We will demonstrate how to determine if your source rock quality is uniform or varied relative to HI over the stratigraphic column, and how to assign a hydrogen index to the different source facies when that source rock quality is not uniform. Further we will illustrate how to estimate the original hydrogen index of the different source facies and assign each a transformation ratio. The transformation ratio is a better proxy for relative maturity, since different source facies may have different present-day hydrogen indices, but their present-day transformation ratio should be quite similar.

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American Association of Petroleum Geologists (AAPG)
Search and Discovery Article

The assessment of the natural temporal variability of source rock units is critical for the understanding of petroleum systems as changes in mineral matrix, organic matter (OM) concentration, and composition can significantly affect expulsion efficiency, primary and secondary migration processes, hydrocarbon quality as well as oil source rock correlation. Already small-scaled fluctuations within sediment successions can critically influence migration efficiency. High-resolution investigation of a well-preserved Lower Jurassic drill core (Toarcian Posidonia Shale) revealed seven discrete and systematic intervals of deviating source rock quality. These were composed of homogenized, non-laminated marls of light grey color, opposed to laminated dark grey background sedimentation. Both lithotypes differentiate not only in mineral composition, but particularly in OM content and quality. An average TOC content of app. 3.9 wt.% reached by the grey marl, is faced by an average TOC content of app. 7.8 wt.% measured for the laminated dark grey marls. Average hydrogen index for grey non-laminated marls was app. 550 mg HC/g TOC, whereas much higher source rock quality with 780 mg HC/g TOC was attained in the dark laminated marls. The marls lower OM concentration and inferior OM quality generates important domains for preferential migration of products, originated from the dark grey layers, or hydrocarbon cluster in case of limited migration into adjacent reservoirs. To assess the potential for preferential intake of hydrocarbons by the coarser-grained light marls and their qualification as migration avenues, artificial maturation experiments were performed with both lithotypes. Hydrocarbon generation was simulated by hydrous pyrolysis in two successive temperature steps 330 °C and 360 °C, covering an early maturity stage, as well as the end of the oil window. Both lithologies show striking differences, not only for the extract yield, but also for the timing of generation. OM quality differences were reflected by variable n-alkane distributions and molecular maturity parameters. High-resolution continuous data produced by non-destructive techniques allows to draw conclusions on i) source rock potential, ii) expulsion and migration processes , and iii) on prediction of petroleum accumulation within the sediment succession. High-resolution investigation in combination with artificial maturation experiments represent an easy-to-use tool in petroleum system analysis.

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American Association of Petroleum Geologists (AAPG)
Search and Discovery Article

The San Joaquin Basin lies west of the Sierra Nevada Mountains and east of the San Andre as Fault. Tens of kilometers of Mesozoic and Cenozoic sediments, including deep-water organic-rich source rocks, deposited in a forearc setting, comprise the basin and have contributed to a petroleum system that generates more than 70 percent of California 's daily oil production and includes three of the 10 largest oilfields in the United States. Based on a comprehensive 3D petroleum systems model of the San Joaquin basin, published by the USGS in 2008, we further refine the modeling to account for the unique depositional and tectonic history of the basin. Here, we compare various basal heat flow scenarios to model hydrocarbon generation and calibrate the results to available temperature and vitrinite reflectance (Vr) data. We investigate two types of crustal models: a McKenzie-type rift model, and a no-rift static crustal thickness model. Crustal stretching models calculate basal heat flow resulting from stretching/thinning of mantle and crust during initial (syn-rift) and thermal (post-rift) subsidence. This method uses rock matrix radiogenic heat production values. It does not account for transient effects resulting from burial and uplift of the basin fill. The static no-rift model, alternatively, calculates the basal heat flow based on a stable or non-thinning crust and mantle over time. This method uses estimated Uranium (U), Thorium (Th), and Potassium (K) concentrations within the rock material to then calculate the rock matrix heat production. Unlike the rift model, it accounts for the transient effects resulting from burial and uplift of the basin fill, which can have a considerable additional effect on the basal heat flow. Given the low probability of crustal stretching as the starting point for basal heat flow in the San Joaquin Basin and considering the forearc nature of the basin as well as the strong concentration of U, K, and Th in the Sierran granites, we focused on and refined the no-rift models. We manually account for the transitional nature of the San Joaquin basement from hot Sierran granite on the east to cool Franciscan oceanic rocks on the west. Radiogenic heat production from solely continental crust results in models that are too warm and cannot be calibrated to well temperature and Vr data. Solely oceanic models are too cool to match well data. ‘Combined crust’ incorporates a seismically derived suture zone that allows for a transition from oceanic to granitic basement, while the ‘intermediate crust’ mixes oceanic and continental radiogenic heat production. These models generate a good match to well data to the east and westward through the transition zone. Additionally, we are able to calibrate to wells off of the Belridge and Lost Hills structures. On structure wells, however, cannot be calibrated with a crustal conductive heat flow scenario and would require (local) elevated heat flows on the order of 20 mW/m 2. This is not in agreement with the generally cooler underlying oceanic crust and suggests that there might be a different and/or additional source of heat flow. Most likely, basin-scale hydrothermal groundwater flow, both along faults and up-structure, could account for elevated Vr and temperature. Convective heat flow would be an additional overprint or enhancement to conductive basal heat flow.

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American Association of Petroleum Geologists (AAPG)
Search and Discovery Article

The driving forces for conventional accumulations (structural or stratigraphic traps) are Forces of Buoyancy which are due to differences in densities of hydrocarbons and water. In contrast, the driving forces for unconventional tight accumulations are Forces of Expulsion which are produced by high pressures. That is an enormous difference and creates unconventional petroleum systems that are characterized by very different and distinctive characteristics. The Force of Expulsion pressures are created by the significant increase in volume when any of the three main kerogen types are converted to hydrocarbons. At those conversion times in the burial history, the rocks are already sufficiently tight so the large volumes of generated hydrocarbons cannot efficiently escape through the existing tight pore system, thus creating a permeability bottleneck that produces an overpressured compartment over a large area corresponding to the proper thermal oil and gas maturities for that basin. The forces initially created in these source rocks can only go limited distances into adjacent tight reservoirs (clastics or carbonates) above or below the source. The exact distance will vary depending on the pressure increase, matrix permeability, and fractures of that specific tight reservoir system. In general, the distances are small, in the orders of 10s to 100s of feet for oil and larger for more mobile gas systems. Those exact distance numbers are subject to ongoing investigations.   A plot of the pressure data versus elevation for a given formation is critical in determining whether an accumulation is conventional or unconventional. Conventional accumulations will have hydrocarbon columns of 10s to 100s of feet with the pressure in the hydrocarbons and that in the water equal at the bottom of the accumulation (at the HC-water contact). In contrast, the unconventional accumulations will show HC column heights of 1000s of feet with the pressure in the hydrocarbon phase and the water phase being the same at the top of the accumulation (at the updip transition zone). Those significant differences are critical for understanding and differentiating these two play types. Because the system is a pore throat bottleneck with very little or minimum lateral migration, the type of hydrocarbon s are closely tied to the thermal maturity required to generate those hydrocarbons. Thus the play concept begins with two important geochemical considerations: (1) where are the source rocks and what are the kerogen types and organic richness (TOC), and (2 ) where are they mature in the basin for oil, condensate, and gas in the basin. These parameters will very quickly define the fairway for the play. Then one has to add the critical information on the reservoirs themselves: composition (brittleness), thickness, and reservoir quality (matrix porosity and permeability). In summary, these tight unconventional petroleum systems (1) are dynamic , and (2) create a regionally inverted petroleum system with water over oil over condensate over gas for source rocks wit h Type I or II kerogen types.

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American Association of Petroleum Geologists (AAPG)
Learn! Blog

Welcome to an interview with the Panton Data Science Team, who are working in drone-based projects where they are pushing the envelope with respect to applications and accuracy, thanks to a unique approach to data collection and analytics.

American Association of Petroleum Geologists (AAPG)
Africa Blog

Network, interact and share expertise with fellow petroleum scientists while learning the latest unconventional reservoir techniques and technologies.

American Association of Petroleum Geologists (AAPG)
Middle East Blog

Seven exciting GTWs in the Middle East Region in 2017!

American Association of Petroleum Geologists (AAPG)
Workshop
Kuala Lumpur, Malaysia
Monday, 2 October Tuesday, 3 October 2023, 8:00 a.m.–5:00 p.m.

AAPG and EAGE have teamed up to deliver the upcoming New Discoveries in Mature Basins workshop to be held from 2-3 October 2023 in Kuala Lumpur, Malaysia. Save the date! Registration to open soon.

American Association of Petroleum Geologists (AAPG)
Workshop
Khobar, Saudi Arabia
Monday, 27 November Wednesday, 29 November 2023, 8:00 a.m.–5:00 p.m.

Mark your calendars and save the date to attend the 5th edition of the AAPG Siliciclastic Reservoirs of the Middle East GTW which will be held for the first time in Al-Khobar, Saudi Arabia from 27-29 November 2023. We look forward to having you on board for the new edition of these popular series.

American Association of Petroleum Geologists (AAPG)
Workshop
Muscat, Oman
Monday, 13 November Wednesday, 15 November 2023, 8:00 a.m.–5:00 p.m.

Exciting announcement for all geoscientists interested in structural styles. The 3rd edition of the AAPG Structural Styles of the Middle East is coming back to Oman from 13-15 November 2023. Come join us to learn all the latest developments on the topic!

American Association of Petroleum Geologists (AAPG)
Workshop
Khobar, Saudi Arabia
Monday, 9 October Wednesday, 11 October 2023, 8:00 a.m.–5:00 p.m.

Join us for the 4th Edition of: "Stratigraphic Traps of the Middle East" workshop. The workshop will be hosted by AAPG in Al Khobar, Saudi Arabia 9-11 October 2023.

American Association of Petroleum Geologists (AAPG)
Workshop
Khobar, Saudi Arabia
Monday, 8 May Wednesday, 10 May 2023, 8:00 a.m.–5:00 p.m.

“Wait! There is a short cut. Turn right from here”. That’s probably the sound of an electric current bypassing the resistive hydrocarbons, in a maze or network of porous media, when traveling from transmitter to receiver. This workshop will serve the participants need with the up to date advancements in describing and characterizing low resistivity and low contrast pay, and eventually, maximize resources.

American Association of Petroleum Geologists (AAPG)
Workshop
Lisbon, Portugal
Wednesday, 21 June Thursday, 22 June 2023, 8:00 a.m.–5:00 p.m.

Secure energy supply and energy immediate availability are key subject for a peaceful and sustainable growth in developed countries and in particular in Europe. This workshop will bring together professionals working in industry and in academia to share experiences, present-day work and future visions related to all geo-subjects involving exploration and development of energy sources in the subsurface.

American Association of Petroleum Geologists (AAPG)
Workshop
Paramaribo, Suriname
Thursday, 2 November Friday, 3 November 2023, 8:00 a.m.–5:00 p.m.

Plan now to attend an interactive in-person workshop with industry leaders, government representatives and technical experts working in the Guyana-Suriname Basin.

American Association of Petroleum Geologists (AAPG)
Workshop
Barranquilla, Colombia
Wednesday, 8 February Thursday, 9 February 2023, 8:00 a.m.–6:00 p.m.

Join technical experts, industry leaders and government representatives for an interactive in-person workshop highlighting onshore and offshore E&P opportunities, new technologies and sustainable development strategies working in Colombia, Trinidad & Tobago, Barbados, Jamaica, and the Dominican Republic.

American Association of Petroleum Geologists (AAPG)
Workshop
Rio de Janeiro, Brazil
Tuesday, 9 May Wednesday, 10 May 2023, 8:00 a.m.–6:00 p.m.

Plan now to attend an interactive in-person workshop with industry leaders, government representatives and technical experts working to help Brazil maintain its E&P capacity while transitioning to a decarbonized economy.

American Association of Petroleum Geologists (AAPG)
Workshop
Muscat, Oman
Monday, 16 January Wednesday, 18 January 2023, 8:00 a.m.–5:00 p.m.

The sedimentary basins of the Middle East have been proved to contain vast hydrocarbon reserves, sourced by some of the most prolific petroleum systems in the world. This is the product of a range of factors, not least the long-lived, relative stability of the Arabian Plate and the presence of multiple, prolific organic source rocks. This workshop will address these and other subjects and to discuss the main challenges present in our current understanding of petroleum systems in the Middle East.

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American Association of Petroleum Geologists (AAPG)
Workshop
Lviv, Ukraine
Thursday, 21 September Friday, 22 September 2023, 8:00 a.m.–5:00 p.m.

Join us for a workshop where experts will  explore the Carpathian foreland and the Dnieper-Donetsk rift basins with a focus not only on hydrocarbons, but the utilization of geothermal resources, hydrogen exploration and CCUS.

American Association of Petroleum Geologists (AAPG)
Workshop
Lisbon, Portugal
Wednesday, 21 June Thursday, 22 June 2023, 8:00 a.m.–5:00 p.m.

This 2-day conference brings together diverse experts working on modern and ancient turbidite, MTDs, contourite and hybrid/mixed systems in order to improve the present-day knowledge, models and predictive power.

American Association of Petroleum Geologists (AAPG)
DL Abstract

Three-dimensional (3D) seismic-reflection surveys provide one of the most important data types for understanding subsurface depositional systems. Quantitative analysis is commonly restricted to geophysical interpretation of elastic properties of rocks in the subsurface. Wide availability of 3D seismic-reflection data and integration provide opportunities for quantitative analysis of subsurface stratigraphic sequences. Here, we integrate traditional seismic-stratigraphic interpretation with quantitative geomorphologic analysis and numerical modeling to explore new insights into submarine-channel evolution.

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Request a visit from Jacob Covault!

American Association of Petroleum Geologists (AAPG)
VG Abstract

The carbonate sequences that were deposited in the now exhumed Tethyan Ocean influence many aspects of our lives today, either by supplying the energy that warms our homes and the fuel that powers our cars or providing the stunning landscapes for both winter and summer vacations. They also represent some of the most intensely studied rock formations in the world and have provided geoscientists with a fascinating insight into the turbulent nature of 250 Million years of Earth’s history. By combining studies from the full range of geoscience disciplines this presentation will trace the development of these carbonate sequences from their initial formation on the margins of large ancient continental masses to their present day locations in and around the Greater Mediterranean and Near East region. The first order control on growth patterns and carbonate platform development by the regional plate-tectonic setting, underlying basin architecture and fluctuations in sea level will be illustrated. The organisms that contribute to sequence development will be revealed to be treasure troves of forensic information. Finally, these rock sequences will be shown to contain all the ingredients necessary to form and retain hydrocarbons and the manner in which major post-depositional tectonic events led to the formation of some of the largest hydrocarbon accumulations in the world will be demonstrated.

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Request a visit from Keith Gerdes!

American Association of Petroleum Geologists (AAPG)
VG Abstract

In comparison with the known boundary conditions that promote salt deformation and flow in sedimentary basins, the processes involved with the mobilization of clay-rich detrital sediments are far less well established. This talk will use seismic examples in different tectonic settings to document the variety of shale geometries that can be formed under brittle and ductile deformations.

Request a visit from Juan I. Soto!

American Association of Petroleum Geologists (AAPG)
DL Abstract

President Biden has laid out a bold and ambitious goal of achieving net-zero carbon emissions in the United States by 2050.  The pathway to that target includes cutting total greenhouse gas emissions in half by 2030 and eliminating them entirely from the nation’s electricity sector by 2035. The Office of Fossil Energy and Carbon Management will play an important role in the transition to net-zero carbon emissions by reducing the environmental impacts of fossil energy production and use – and helping decarbonize other hard-to abate sectors.

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Request a visit from Jennifer Wilcox!

American Association of Petroleum Geologists (AAPG)
DL Abstract

Around 170 million years ago, the Gulf of Mexico basin flooded catastrophically, and the pre-existing landscape, which had been a very rugged, arid, semi-desert world, was drowned beneath an inland sea of salt water. The drowned landscape was then buried under kilometers of salt, perfectly preserving the older topography. Now, with high-quality 3D seismic data, the salt appears as a transparent layer, and the details of the drowned world can be seen in exquisite detail, providing a unique snapshot of the world on the eve of the flooding event. We can map out hills and valleys, and a system of river gullies and a large, meandering river system. These rivers in turn fed into a deep central lake, whose surface was about 750m below global sea level. This new knowledge also reveals how the Louann Salt was deposited. In contrast to published models, the salt was deposited in a deep water, hypersaline sea. We can estimate the rate of deposition, and it was very fast; we believe that the entire thickness of several kilometers of salt was laid down in a few tens of thousands of years, making it possibly the fastest sustained deposition seen so far in the geological record.

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Request a visit from Frank Peel!

American Association of Petroleum Geologists (AAPG)
VG Abstract

The Betic hinterland, in the westernmost Mediterranean, constitutes a unique example of a stack of metamorphic units. Using a three-dimensional model for the crustal structure of the Betics-Rif area this talk will address the role of crustal flow simultaneously to upper-crustal low-angle faulting in the origin and evolution of the topography.

Request a visit from Juan I. Soto!

American Association of Petroleum Geologists (AAPG)
DL Abstract

Local sea-level changes are not simply a function of global ocean volumes but also the interactions between the solid Earth, the Earth’s gravitational field and the loading and unloading of ice sheets. Contrasting behaviors between Antarctica and Scotland highlight how important the geologic structure beneath the former ice sheets is in determining the interactions between ice sheets and relative sea levels.

Request a visit from Alex Simms!

American Association of Petroleum Geologists (AAPG)
DL Abstract

As oil and gas exploration and production occur in deeper basins and more complex geologic settings, accurate characterization and modeling of reservoirs to improve estimated ultimate recovery (EUR) prediction, optimize well placement and maximize recovery become paramount. Existing technologies for reservoir characterization and modeling have proven inadequate for delivering detailed 3D predictions of reservoir architecture, connectivity and rock quality at scales that impact subsurface flow patterns and reservoir performance. Because of the gap between the geophysical and geologic data available (seismic, well logs, cores) and the data needed to model rock heterogeneities at the reservoir scale, constraints from external analog systems are needed. Existing stratigraphic concepts and deposition models are mostly empirical and seldom provide quantitative constraints on fine-scale reservoir heterogeneity. Current reservoir modeling tools are challenged to accurately replicate complex, nonstationary, rock heterogeneity patterns that control connectivity, such as shale layers that serve as flow baffles and barriers.

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Request a visit from Tao Sun!

American Association of Petroleum Geologists (AAPG)
VG Abstract

Production from unconventional petroleum reservoirs includes petroleum from shale, coal, tight-sand and oil-sand. These reservoirs contain enormous quantities of oil and natural gas but pose a technology challenge to both geoscientists and engineers to produce economically on a commercial scale. These reservoirs store large volumes and are widely distributed at different stratigraphic levels and basin types, offering long-term potential for energy supply. Most of these reservoirs are low permeability and porosity that need enhancement with hydraulic fracture stimulation to maximize fluid drainage. Production from these reservoirs is increasing with continued advancement in geological characterization techniques and technology for well drilling, logging, and completion with drainage enhancement. Currently, Australia, Argentina, Canada, Egypt, USA, and Venezuela are producing natural gas from low permeability reservoirs: tight-sand, shale, and coal (CBM). Canada, Russia, USA, and Venezuela are producing heavy oil from oilsand. USA is leading the development of techniques for exploring, and technology for exploiting unconventional gas resources, which can help to develop potential gas-bearing shales of Thailand. The main focus is on source-reservoir-seal shale petroleum plays. In these tight rocks petroleum resides in the micro-pores as well as adsorbed on and in the organics. Shale has very low matrix permeability (nano-darcies) and has highly layered formations with differences in vertical and horizontal properties, vertically non-homogeneous and horizontally anisotropic with complicate natural fractures. Understanding the rocks is critical in selecting fluid drainage enhancement mechanisms; rock properties such as where shale is clay or silica rich, clay types and maturation , kerogen type and maturation, permeability, porosity, and saturation. Most of these plays require horizontal development with large numbers of wells that require an understanding of formation structure, setting and reservoir character and its lateral extension. The quality of shale-gas resources depend on thickness of net pay (>100 m), adequate porosity (>2%), high reservoir pressure (ideally overpressure), high thermal maturity (>1.5% Ro), high organic richness (>2% TOC), low in clay (<50%), high in brittle minerals (quartz, carbonates, feldspars), and favourable in-situ stress. During the past decade, unconventional shale and tight-sand gas plays have become an important supply of natural gas in the US, and now in shale oil as well. As a consequence, interest to assess and explore these plays is rapidly spreading worldwide. The high production potential of shale petroleum resources has contributed to a comparably favourable outlook for increased future petroleum supplies globally. Application of 2D and 3D seismic for defining reservoirs and micro seismic for monitoring fracturing, measuring rock properties downhole (borehole imaging) and in laboratory (mineralogy, porosity, permeability), horizontal drilling (downhole GPS), and hydraulic fracture stimulation (cross-linked gel, slick-water, nitrogen or nitrogen foam) is key in improving production from these huge resources with low productivity factors.

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Request a visit from Ameed Ghori!

American Association of Petroleum Geologists (AAPG)

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