Historically, the exploration for oil and gas resources has focused on identifying structural and stratigraphic traps associated with conventional accumulations. The importance of source rocks was also recognized to understand their generative potential and the timing of hydrocarbon expulsion relative to the formation of those traps. In the past 20 yr, since unconventional resources started being developed

Carrier beds are lateral migration pathways that link source rocks with reservoirs in conventional petroleum plays. Carrier beds may—but need not—have the same reservoir properties as the conventional reservoirs supplied by them. Indeed, the downdip limits of many conventional fields are defined by changes in porosity and, more often, permeability, associated with a change in facies between the carrier

Historically, the offshore Mancos play of the San Juan Basin has produced oil from noncommercial to marginally commercial reservoirs consisting of dark-gray marine shale with thin beds and laminae of fine-grained sandstone of limited permeability. During the last decade, horizontal drilling with horizontal wells has resulted in substantially increased production. However, placement of the offshore

Carrier-bed plays are a new type of unconventional oil play that are currently being developed in North America. The reservoirs are generally low quality because of any of the following: thin beds (heterolithic strata), diagenesis, or burrowing (heterogeneous, mixing of sandstones or carbonates and mudstones). The carrier beds are pervasively hydrocarbon saturated and can occur over an areally extensive

Shallow-marine reservoirs of the Upper Cretaceous Cardium Formation contain one of the largest light oil accumulations in Canada, which have been exploited since the 1950s. Since 2008, multistage fractured horizontal wells have revived this play. This study presents a reservoir characterization of the offshore to shoreface unconventional reservoirs of the Cardium Formation in the halo play along the

Typical meter-scale lithofacies cycles from the Wolfcamp A in the Delaware and Midland Basins comprise basal carbonate facies overlain by calcareous or siliceous mudrocks. Siliceous mudstones are the most organic-rich facies with high total organic carbon (TOC > 3 wt. %), whereas thin carbonate beds have the lowest organic matter (OM) content among the lithofacies present (TOC < 1 wt. %). To determine

The Williston Basin has proven to be a global super basin. Initially, development across this basin was dominated by conventional production from the Madison Group and Ordovician oil systems; however, with the development of unconventional play opportunities, the biggest resource in the Williston Basin is now the Middle Member of the Bakken Formation. The Middle Member was not pursued as a reservoir

The main controls on petroleum accumulations in sedimentary basins include source-rock distribution, thermal maturity, migration pathways, and structural and stratigraphic traps. Whereas shale plays and conventional reservoirs are end members governed by contrasted geological processes, unconventional hybrid systems represent a continuum between them and share common characteristics with both. The

The accurate prediction of overpressure before drilling is important for hydrocarbon exploration. It is almost impossible to directly predict the multiple origin overpressures via the existing methods that are related to anomalous porosity in a deep fold-thrust belt. Considering the Kelasu thrust belt (KTB) as an example, the compacting and loading curves in the KTB at the maximum burial period were

Hydraulic-driven faults and fractures are important subsurface fluid-flow pathways, yet their seismic expressions are poorly documented. This paper uses high-quality three-dimensional seismic data to investigate curved, strata-bound domino-style faults above which a pockmark field is observed and interpreted to be associated with their formation. The faulted interval covers an area of 24 km2 and is

Point-bar deposits, although readily recognizable in most successions, are notoriously challenging to map and correlate accurately, particularly in the subsurface. Sedimentologic interpretations from microresistivity image logs, by contrast, offer an unparalleled method of accurately reconstructing point-bar architectural elements and mapping their distribution. Using an example from the Lower Cretaceous

Clay microporosity in sandstones can cause erroneously high water saturation calculations if not properly accounted for and reduces effective pore space when evaluating a formation. We conducted a petrographic study to characterize and quantify the clay mineral microporosity of the fluvial facies of the Mississippian Cypress Sandstone in the Illinois Basin. These data helped achieve more accurate saturation

The origins of overpressure in the central Xihu depression have been accepted to result from disequilibrium compaction and hydrocarbon generation. This study uses organic matter correction of the log data in source rocks and five empirical methods (the multilogging combination method, Bowers’ method, the sonic velocity–density crossplot method, the porosity method, and the pressure inversion method)

Despite documented pitfalls, many geoscientists continue to publish problematic oil–oil correlations based on compound ratios determined from “dead oil” that lacks volatiles. Mixtures of petroleum from more than one source rock pose issues for assigning genetic affinity, proportions of contributing end members, and predicted gas–liquid ratios. Compound ratios mix in nonlinear fashion for end members

Studies of near-seabed data sets show that salt tectonics controls the distribution and architecture of deep-water reservoirs in many salt-influenced basins. It is typically difficult, however, to study the distribution and stratigraphic evolution of depositional systems preserved at deeper, economically significant depths, reflecting poor seismic imaging of steeply dipping strata flanking high-relief

Distribution of volcanic reservoirs in Xujiaweizi half graben is controlled by both faults and sealing layers where their integrity could have been compromised. This paper documents the distribution of sealing units of the Denglouku and Yingcheng Formations based on seismic and well-log data to delineate all of the reservoirs with proper cap rocks within the volcanic Yincheng Formation via the relationship

The Upper Cretaceous Niobrara Formation in the Denver-Julesburg (D-J) Basin, United States, records late Turonian–early Campanian transgressive–regressive cycles that governed the rhythmic character of pelagic and detrital sedimentation along the former carbonate ramp of the Western Interior seaway (WIS). The general stratigraphic and architectural complexity of the full Niobrara section has long been

The purpose of this research was to examine paleoenvironments, hydrothermal activity, and seawater restriction of the lower Cambrian Niutitang Formation shale gas reservoir in the eastern Xuefeng uplift and to determine factors affecting organic matter (OM) enrichment. In the studied borehole Xiangan 1 well in western Hunan Province, the Niutitang Formation can be subdivided into the Niu1, Niu2, and

Integration of geomechanical, geological, geochemical, and petrophysical characterization is critical to enhance production from organic-rich mudrocks. This paper introduces an integrated rock classification method in the Eagle Ford Formation shales and marls in southern Texas, consisting of organic-rich fossiliferous marine shale deposited during the Late Cretaceous. A joint inversion of triple-combo

Liquid permeability of sedimentary rocks is relevant in several contexts, but gas permeability is easier to measure, so liquid permeability is typically estimated from gas permeability via empirical or semiempirical correction procedures. A frequently used and trusted procedure is the well-known Klinkenberg correction, which is based on the pressure dependence of gas permeability. However, from gaseous

In eastern Texas, a thick (150–200 ft) interval of Lower Cretaceous upper Glen Rose D strata was deposited in the Houston trough intrashelf basin landward of the Stuart City reef margin and seaward of the main eastern Texas intrashelf basin. The stratigraphic section in this intrashelf basin forms a primarily oil-bearing hydrocarbon system where porous grainstones in the Alabama Ferry and Fort Trinidad

The Nanpu sag is a typical petroliferous area in the Bohai Bay Basin. Crude oil density and viscosity, natural gas components and biomarker chemistry of crude oil, and shale sample extracts were analyzed to determine the characteristics and the origin of oil and gas and the effects of source rock on oil and gas distribution. The discovered heavy oil present in the shallow layers of the Liuzan, Gaoshangpu

Mass-transport complexes (MTCs) are one of the most sedimentologically and seismically distinctive depositional elements in deep-water depositional systems. Seismic reflection data provide spectacular images of their structure, size, and distribution, although a lack of borehole data means there is limited direct calibration between MTC lithology and petrophysical expression or knowledge of how they

Several fractal models have been widely used to evaluate the heterogeneity of tight sandstones based on mercury intrusion porosimetry (MIP). However, most of these models are pore fractal models rather than surface fractal models. Therefore, the suitability of existing surface fractal models for tight sandstones and the consistency of their results remain questionable. In the present work, a series

During the years 2007–2015, a new direction for industry was appearing. Revitalized waves of production emerged from the world’s richest petroleum bearing basins (Ahlbrandt, 2015; Fryklund, 2018). An all-out effort to optimize extensive infrastructure, using new technology and basin scale thinking, required an action plan for geoscientists.In 2018–2020, AAPG responded with a new series of programs

An important step in the evaluation of a play or prospect is to consider the potential supply of petroleum charge, which is ultimately constrained by masses and volumes supplied by the source bed. The two factors limiting the mass of petroleum expelled from the organic matter in the source bed are (1) its initial expulsion potential and (2) the cumulative fraction of potential that has been expelled

The West Texas (Permian) Super Basin is the prototype super basin. The basin has produced 28.9 billion bbl of oil and 203 TCF of gas (63 billion BOE, 1920–2019). The US Geological Survey and Bureau of Economic Geology estimate this super basin has remaining reserves of 120–137 billion BOE, twice the volume produced during the first 100 yr of hydrocarbon production. During the past decade, the West

The Paleozoic sedimentary section of the Arabian plate recorded the effects of numerous fluctuations in sea level and gentle epeirogenic movements. Eustatic changes in sea level over the Arabian plate resulted in transgressions and regressions and created many local and regional unconformity surfaces, identified by missing section and nondeposition. The distant deformation of the Caledonian tectonic

More than 50 basins worldwide are identified as “super basins,” defined as a basin with cumulative production of at least 5 billion BOE (∼0.8 billion m3) and with future production potential of more than 5 billion BOE. By this definition, the Anadarko Basin is a super basin; cumulative production is close to 50 billion BOE (∼7.9 billion m3) and unconventional reservoirs have the potential to produce

North Alaska Super Basin oil fields have produced more than 18 billion bbl of oil with at least 5 billion bbl remaining in existing fields, and estimated yet-to-find resources exceed 10 billion bbl in three prolific petroleum systems. Since discovery of the two largest United States conventional oil fields at Prudhoe Bay and Kuparuk River in the 1960s, technological advancements including three-dimensional

Global analogues are widely used across the exploration and production (E&P) life cycle. Analogues, used in conjunction with primary data, expand the knowledge of both the individual and team and develop insights that are not possible from using either local data or individual experience in isolation. Difficulties in the application of analogues arise when the analogues are not selected consistently

Unconventional reservoir performance is assessed and quantified via integration of compositional, rock fabric, and static mechanical property analyses that are routinely performed on drill core or cuttings. This approach has several limitations; for example, it can only be used where drill core and cuttings are available, and comprehensive analysis may be cost prohibitive at the full scale of a resource

The main source rocks, hydrocarbon generative subbasins, hydrocarbon generation periods, resource potential, and the relationship between the trap evolution history and hydrocarbon generation history are important problems associated with oil and gas exploration. In this study, we develop a three-dimensional geological model with respect to the Mesozoic and Cenozoic strata of the northern margin of

The Bongor Basin in southern Chad is one of the Cretaceous–Paleogene rift basins developed on the Precambrian crystalline basement and has been confirmed as a petroliferous basin in the last decade. Less than 400 m of Cenozoic unconsolidated sediments are separated by an unconformity from an underlying section of Lower Cretaceous units, in turn separated by another unconformity from underlying Precambrian

China has been said to have the largest putative shale gas resources in the world. The highest potential occurs in the Sichuan Basin, with the overmature Qiongzhusi (Cambrian) and Longmaxi (Silurian) Formations as prime exploration targets. Here, the likelihood of late gas formation is examined using less mature equivalents from the Georgina Basin (Australia) and the Baltic Basin (Lithuania). We consider

Magnetic susceptibility (MS) is a logging method commonly used for investigating lithostratigraphic features in marine sediments or petrophysical parameters. In this paper, an application of MS core logging as a tool identifying paleoenvironment and potential high organic matter content will be presented. The aim of the study was to define the relationship between magnetic methods, Rock-Eval pyrolysis

The relationship between water saturation and resistivity index in tight sandstone reservoirs cannot be simply expressed using the Archie equation. This makes the saturation exponent difficult to determine and the water saturation estimation significantly challenging. Based on fractal theory and the Archie equation, a theoretical power function relationship is used to predict the resistivity index

Despite the obvious link between hydrocarbon seepage at the surface and the activity of petroleum systems at depth, the majority of studies on seep carbonates concentrate on shallow aspects, whereas they are rarely oriented toward a source-to-sink perspective. Here, seep carbonates are conceptualized as a key element for analyzing petroleum systems at basin scale. Mapping of a 150-m-thick, 200-m-wide

Advances and availability of deep learning (DL) software have recently allowed the development, testing, and deployment of automated image classification schemes for sedimentary features from core images. The development of these methods is especially relevant for extracting useful geological features from otherwise unused core photographs. This paper demonstrates and tests the use of a DL workflow

This geologic note provides a lookback on lookbacks, hopefully to spur further interest by companies in generating learning from exploration experience, rather than being victimized by repeated mistakes to which exploration assessment may unknowingly be exposed. The lookback contribution to portfolio management is properly called performance tracking. Likely inspired by the after-action review process

Bedding-parallel veins of fibrous calcite (also called “beef”) occur in many sedimentary basins, especially those containing low-permeability strata with organic source material for petroleum. The formation of such veins is commonly linked with fluid overpressure in these source rocks. In this review, we demonstrate that beef veins are most commonly present in foreland basins worldwide or in basins

Middle and Upper Devonian gas shales of the Appalachian Basin host a sequence of mode I cracks from early veins to late unmineralized joints. These fractures develop during a cycle of burial and exhumation starting with horizontal veins, then vertical veins, then vertical joints, and ending with pancake joints. Veins are most common in the cross-fold orientation in gas shale of the deep hinterland

Many of those assessing geochemical data have taken a “cookbook” approach to interpretation. Such an approach generally does not take into consideration the limitations of the different data sets. Among these data sets are those associated with thermal maturity, which guides the interpretation of the extent of generation and hydrocarbon phase.The temperature of peak pyrolysis generation (Tmax) is commonly

Organic geochemical and petrographic analyses were carried out on Paleozoic core samples to evaluate the source rocks in Kuwait. This is a pioneer study because most of the petroleum exploration targets the Mesozoic petroleum system. The samples were collected from four wells that penetrated the Permian Khuff Formation and the Carboniferous–lower Permian Unayzah Formation. Standard organic geochemical

Carbon isotope analyses of fluid inclusion gases trapped in quartz grains in nine sandstone core samples from eight wells in the Baiyun depression and the Panyu lower uplift were performed to determine the source and thermal maturity of the paleo-natural gases. Two-dimensional thermal and hydrocarbon generation history modeling of the source rocks coupled with the carbon isotopic results of the fluid

A new method is presented to identify chemostratigraphic zones by applying principal component (PC) analysis and to interpret geological boundaries based on PC curves. The PC data were calculated using inductively coupled plasma–optical emission spectrometry and inductively coupled plasma–mass spectrometry, with data acquired for 50 chemical elements in the range Na–U. In the present study, a total

X-ray fluorescence chemostratigraphy of the Cenomanian–Turonian Woodbine and Eagle Ford Groups in the southern parts of the East Texas Basin highlights significant mudstone chemical heterogeneities that commonly are difficult to observe or quantify at the macroscale. Several key elements, namely, Ca, Si, Mo, Mn, and Ni, were correlated to depositional conditions and used in a hierarchical cluster analysis

Shallow production of sweet high-gravity oil from the Upper Devonian Berea Sandstone in northeastern Kentucky has caused the region to become the leading oil producer in the state. Potential nearby source rocks, namely, the overlying Mississippian Sunbury Shale and underlying Ohio Shale, are immature for commercial oil generation according to vitrinite reflectance and programmed pyrolysis analyses

With development dating from the 1800s, the Devonian Berea Sandstone has a long history of oil and gas development in the Appalachian Basin. A new phase of development began in northeastern Kentucky in 2011 with production of high-gravity oil from horizontal wells at depths less than 2200 ft (<671 m). Oil production in areas previously unproductive or primarily gas productive was unexpected because

Since 2011, the Devonian Berea Sandstone in northeastern Kentucky has produced oil where thermal maturity studies indicate that likely source rocks, namely, the Devonian Ohio Shale and Mississippian Sunbury Shale, are thermally immature. Downdip, where source rocks are mature for oil, the Berea Sandstone and Ohio Shale primarily produce gas. To investigate this thermal maturity discordancy, the molecular

Recent production of light sweet oil has prompted reevaluation of Devonian petroleum systems in the central Appalachian Basin. Upper Devonian Ohio Shale (lower Huron Member) and Middle Devonian Marcellus Shale organic-rich source rocks from eastern Ohio and nearby areas were examined using organic petrography and geochemical analysis of solvent extracts to test ideas related to organic matter sources

As part of a study to determine the origin of oil and gas in the Berea Sandstone in northeastern Kentucky and southeastern Ohio, 158 samples of organic-rich shale from the Upper Devonian Olentangy and Ohio Shales and the Lower Mississippian Sunbury Shale, collectively referred to as the “black shale,” were collected and analyzed from 12 cores. The samples were analyzed for total organic carbon (TOC)

Berea reservoirs in eastern Kentucky are developed in tight siltstone and sandstone. Precision horizontal drilling provides access to thin (<10 ft) stratigraphic traps, and a new shallow oil play has resulted. Bedding, porosity and permeability data, x-ray diffraction mineralogy data, and petrography are examined and compared in five cores to better understand stratigraphic traps and pore types.Upper

After reaching a plateau, the production of oil reservoirs starts to decline, which substantially determines their life expectancy. Declining production data from three 58- to 71-yr-old oil pools in Alberta, Canada, have been documented and analyzed to show and predict their life span. Two declining phases of oil production can be distinguished: a short 4–11-yr substantially declining phase and a long

The risk of anthropogenic earthquakes created by fluid injection and completion of horizontal wells is managed using maps of recent seismicity and by creating buffer zones around previously mapped faults. In Madison and Fayette Counties, Ohio, faults were identified in 1969 using analogue paper-recorded seismic reflection technology. These faults were located primarily by mapping a prominent “Conasauga

Oil and gas accumulations in the sandy conglomerate diagenetic traps that developed in the fan delta of the Triassic Baikouquan Formation of the Mahu sag, Junggar Basin, differ from stratigraphic accumulations controlled by sedimentary facies. This study uses conventional gas chromatography–mass spectrometry measurements, mineralogical and petrological data, fluid inclusion analyses, and geophysical

Gas storage capacity estimates of shales are routinely assessed using laboratory data from unconfined methane sorption and porosity measurements. In this study, the stress dependence of the methane excess sorption capacity and specific pore volume are investigated simultaneously. Experiments were performed on dry core plugs (Cambrian–Ordovician Alum, Jurassic Bossier, Late Cretaceous Eagle Ford, and

Within New Zealand, the East Coast Basin represents the primary shale oil and gas play in which the Whangai Formation is widespread. This formation is oil and gas prone and prevalent throughout a large area of the East Coast Basin and is typically composed of the Upper Calcareous, Porangahau, and Rakauroa Members.The primary goal of this study was to develop an integrated methodology to define the

The northeastern Sichuan Basin thrust belt located in southwestern China, is a large-scale intracontinental thrust system with multiple detachments represented by a series of subparallel chevron anticlines. We conduct a comprehensive study of the geometry and kinematics of the thrust belt and its implications for the petroleum system based on seismic-reflection profile interpretation, field investigation

Unconventional opal-A and opal-CT diatomaceous reservoirs in the Monterey Formation of the San Joaquin Valley in California have produced for more than 30 yr. These opal-A reservoirs are characterized by high porosity (>50%) and low permeability (<10 md) making them a challenge to produce. Five diatomaceous reservoirs in the Monterey Formation are described, with locations at Lost Hills, Cymric, and