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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)
Middle East Blog

You are invited to prepare a poster display for presentation for the workshops coming up this spring.

American Association of Petroleum Geologists (AAPG)
Explorer Historical Highlights

Wildfires might be what come to mind when most people think of northeastern Alberta, owing to recent news coverage of the record evacuation of about 88,000 people from the Fort McMurray area. Current events notwithstanding, however, northeastern Alberta is historically best known for its huge bitumen resources.

American Association of Petroleum Geologists (AAPG)
Explorer Policy Watch

It was a hard-fought and divisive political season – one that has raised anxiety levels both in the United States and abroad. It is now up to the new president and the Republican-controlled 115th Congress to get to work.

American Association of Petroleum Geologists (AAPG)
Explorer Geophysical Corner

Seismic discontinuity attributes such as coherence and curvature are routinely applied to 3-D seismic data volumes to delineate faults or fractures, channel and reef edges, and other geological features.

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

By investigating petroleum systems, we can potentially reduce the risk of hydrocarbon charge and help define the commerciality of potential prospect and leads. Predicting oil versus gas, making predictions on oil quality or condensate-gas ratio can allow informed decisions to be made pre-drill. Advances have been made in the recent past to address subjects as diverse as, non-hydrocarbon gases, the potential for unconventional hydrocarbons, the role of hydrodynamics, the presence of tilted fluid contacts, the formation of microbial gases, phase prediction and in-reservoir fluid alteration processes. The purpose of this workshop is to address these and other subjects and to discuss the main challenges present in our current understanding of petroleum systems in the Middle East. Mark your calendar to attend this pertinant and revealing workshop.

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American Association of Petroleum Geologists (AAPG)
Workshop
Al-Khobar, Saudi Arabia
Monday, 7 November Wednesday, 9 November 2022, 8:00 a.m.–5:00 p.m.

Join us for the 2nd AAPG Integrated Emerging Exploration Concepts GTW, which will be held in Dhahran on 7-9 November 2022. The workshop will emphasize the importance of developing new approaches and adopting best practices to generate and mature new exploration ideas.

American Association of Petroleum Geologists (AAPG)
Workshop
Trabzon, Turkey
Tuesday, 6 September Wednesday, 7 September 2022, 8:00 a.m.–5:00 p.m.

Join us in Trabzon, Turkey, for "Exploration and Production in the Black Sea Region and Super-Basin Thinking" a AAPG Europe Geoscience Workshop to be held on September 6-7, 2022.

American Association of Petroleum Geologists (AAPG)
Short Course
Tunis, Tunisia
Monday, 12 September 2022, 8:00 a.m.–4:30 p.m.

This short course will comprise lectures, short exercises and discussion sessions. The course will focus on a number of case studies that link outcrop and subsurface geology and have relevance to petroleum exploration and production. Case studies range from Silurian to Miocene in age and come from North African and Mediterranean Basins. The course builds on basic knowledge of sedimentary geology but does not require specialist skills from participants.

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American Association of Petroleum Geologists (AAPG)
Field Seminar
Tunis, Tunisia
Thursday, 15 September Saturday, 17 September 2022, 8:00 a.m.–5:00 p.m.

The structurally complex area of Northern Tunisia (onshore and offshore) corresponds to a fold and thrust belt (FTB) zone, a result of the tertiary compressional/trans-pressional tectonics (Pyrenean and Alpine). This field trip will focus on the different structural styles in the different segments of the area using a rich amount of outcropping and subsurface data and their relationships within the petroleum systems components (source rock and reservoir Rock).

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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)
Short Course
Sunday, 25 September 2022, 8:30 a.m.–9:30 a.m.

Date: 25 September 2022 Time: 8:30am - 4:30pm Course Instructor: Alberto Ortiz, Net Zero Carbon Solutions Registration Fee: $530 Registration Deadline: 25 August 2022 Short Course registration is included as part of the GTW registration process. The petrophysical characterization of unconventional shale-type reservoirs has been one of the most approached and relevant issues in the oil and gas industry in the last 8 years. This is because after several years, the operating companies comprehended the impact that an appropriate characterization of the reservoir has on their project economics. Another reason for this were the technical obstacles encountered in the measurement of petrophysical properties such as porosity, saturation and permeability due to the complexity of this type of reservoir. Obstacles and limitations not only relate to laboratory measurements but also to electrical logging tools. As a consequence of this, nowadays, petrophysical evaluations in this type of reservoir do not have standardized workflows established and accepted worldwide as is the case for conventional reservoirs. This motivates the professionals involved in the study of this type of rocks to dedicate a lot of effort in the validation of the technologies used, and sometimes it is difficult for them to understand the results, the evaluation of uncertainties and the construction of petrophysical models with results and representative parameters of the subsurface conditions. This course will focus on providing key knowledge for a better characterization of the rock both in the aspects related to the matrix represented by mineralogy and kerogen as well as the fluids present. The approach will be based on the convergence of different technologies that support and give robustness to the results. The contents that will be provided will include laboratory testing techniques and petrophysical evaluation of electrical well logs for unconventional shale-type reservoirs. The contents provided will cover a variety of studies based on the most diverse physical principles that will include the latest advances and techniques used in the industry such as Nuclear Magnetic Resonance, Spectroscopy, Dielectric, Computed axial tomography and SEM images, among others. As a result of this, attendees will have tools that allow a more comprehensive understanding of this type of rocks, a better assessment of the uncertainty of the model used and the necessary steps to improve its precision, accelerating the learning curve. The contents provided will also allow knowing the critical parameters that must be taken into account for the definition of areas to be drilled. Course Topics Reservoir heterogeneity characterization from outcrops to lab data and electrical logging. Most relevant unconventional plays of the world. Main characteristics. The petrophysical model. Components and definitions, construction, uncertainties, strengths and weakness. Lab studies: porosity, saturation, mineralogy, organic geochemistry and permeability. Electrical logging response on unconventional shale plays: triple combo, NMR, NMR T1T2, nuclear spectroscopy, spectral GR, dielectric. The effect of maturity on kerogen. Challenges on water saturation calculation. Data integration. Interpretation workflows and core calibration.

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American Association of Petroleum Geologists (AAPG)
Workshop
Lisbon, Portugal
Thursday, 18 May Friday, 19 May 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)
Workshop
Manama, Bahrain
Monday, 26 September Wednesday, 28 September 2022, 8:00 a.m.–5:00 p.m.

The workshop aims to provide a comprehensive understanding of the source rocks in the Middle East. The technical program is developed in a way that coves the depositional environments and transport processes, basin modeling and detailed rock characterisation including geochemisty, geomechanics and petrophysics.

American Association of Petroleum Geologists (AAPG)
VG Abstract

Microseismicity induced by hydraulic fracture stimulation of a horizontal well was mapped with a near-surface buried array. Distinct linear trends of events were not parallel to the direction of fast shear wave polarization measured in the reservoir with a crossed-dipole anisotropy tool. Analysis of core from a nearby well revealed numerous calcite-filled fractures that did not induce shear wave polarization, but did significantly impact the failure behavior of the reservoir rock during the stimulation treatment. Hydraulic fracture simulation with DFN modeling and source mechanism analysis supports the interpretation of reactivated existing fractures rather than the formation of hydraulically-induced tensile fractures.

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Request a visit from Sherilyn Williams-Stroud!

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

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)
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)
VG Abstract

This is a less-technical education topic. It can be condensed to an hour or given as 2 two-hour sessions. It stresses selected controversial aspects of fracking that touch some combination of environment and economics and includes a short video of how fracking is done.

Request a visit from David Weinberg!

American Association of Petroleum Geologists (AAPG)
VG Abstract

The following short course option was developed for geology and geophysics students that have not had much exposure to how geoscience is applied in industry. It can be tailored for undergraduate juniors and seniors or graduate students. The agenda can be modified to meet specific needs and time constraints. Contact the presenter to discuss options.

Request a visit from Fred Schroeder!

American Association of Petroleum Geologists (AAPG)
VG Abstract

The following short course option was developed for geology and geophysics students that have not had much exposure to how geoscience is applied in industry. It can be tailored for undergraduate juniors and seniors or graduate students. The agenda can be modified to meet specific needs and time constraints. Contact the presenter to discuss options.

Request a visit from Fred Schroeder!

American Association of Petroleum Geologists (AAPG)
VG Abstract

Analysis of microseismicity induced by hydraulic fracture stimulation in the Marcellus Shale shows changes in stress state for different zones of failure. During the treatment, shear failure occurs on both the J1 and J2 fracture orientations in response to different maximum stress orientations, indicating localized changes in the orientation during the treatment. Reactivation of a fault near the wellbore is associated with failure mechanisms with a higher volumetric component, indicating possible inflation of faults and fractures by the introduction of the slurry. Quantification of the stress conditions that are associated with inflation could potentially be used to optimize the stimulation by identifying which fractures will preferentially take on slurry volume.

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Request a visit from Sherilyn Williams-Stroud!

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)
VG Abstract

This lecture will discuss the differences between carbonates and siliciclastics from their chemical composition through their distributions in time and space. Building on these fundamental differences, we will explore the challenges carbonates pose to petroleum geologists in terms of seismic interpretation, reservoir quality prediction, field development, etc. Peppered with humorous personal stories, still raging academic debates, and the heartfelt frustrations of real industry professionals, the aim is to inspire students and young professionals to rise to the occasion and embrace the reservoir rocks that petroleum geologists love to hate.

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Request a visit from Noelle Joy Purcell!

American Association of Petroleum Geologists (AAPG)

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