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Microseismic technology continues to pay its way as an exploration tool. A buried array installed in the Williston Basin is helping Newfield Exploration Co. of Denver increase efficiency, according to company geologists.

Explorer Article

Shale formations can confound even the savviest geoscientist when it comes to determining the inner workings of the rock. After expert evaluation, even the most attractive prospecting deal can be a tough sell. And there’s almost always a new piece to each of these puzzles that requires some sophisticated high-tech explaining.


Umiat field in northern Alaska is a shallow, light-oil accumulation with an estimated original oil in place of more than 1.5 billion bbl and 99 bcf associated gas. The field, discovered in 1946, was never considered viable because it is shallow, in permafrost, and far from any infrastructure. Modern drilling and production techniques now make Umiat a more attractive target if the behavior of a rock, ice, and light oil system at low pressure can be understood and simulated.

The Umiat reservoir consists of shoreface and deltaic sandstones of the Cretaceous Nanushuk Formation deformed by a thrust-related anticline. Depositional environment imparts a strong vertical and horizontal permeability anisotropy to the reservoir that may be further complicated by diagenesis and open natural fractures.

Experimental and theoretical studies indicate that there is a significant reduction in the relative permeability of oil in the presence of ice, with a maximum reduction when connate water is fresh and less reduction when water is saline. A representative Umiat oil sample was reconstituted by comparing the composition of a severely weathered Umiat fluid to a theoretical Umiat fluid composition derived using the Pedersen method. This sample was then used to determine fluid properties at reservoir conditions such as bubble point pressure, viscosity, and density.

These geologic and engineering data were integrated into a simulation model that indicate recoveries of 12%–15% can be achieved over a 50-yr production period using cold gas injection from five well pads with a wagon-wheel configuration of multilateral wells.


In recent years, artificial intelligence techniques, and neural networks in particular, have gained popularity in solving complex nonlinear problems. Permeability, porosity and fluid saturation are three fundamental characteristics of reservoir systems that are typically distributed in a spatially non-uniform and non-linear manner. In this context, porosity and permeability prediction from well log data is well-suited to neural networks and other computer-based techniques. The present study aims to estimate formation porosity and permeability from digital well log data using an artificial neural network (ANN) approach. A representative case study from the Alberta Deep Basin is presented. Five well log responses (Gamma Ray Log (GR), Deep Resistivity (RD), Formation Density (DEN), Neutron Porosity (PHIN) and Density Porosity (PHID)) are used as inputs in the ANN to predict porosity and permeability. Core porosity and permeability are used as target data in the ANN to test the prediction. The accuracy of the ANN approach is tested by regression plots of predicted values of porosity and permeability with core porosity and permeability respectively. Excellent matching of core data and predicted values reflects the accuracy of the technique. ANN is a fast and accurate method for the prediction of reservoir properties and could be applied in reservoir modeling and characterization.

Explorer Article

"Breakthrough elegance": ExxonMobil geologists Jeff Ottmann and Kevin Bohacs shared their highly-coveted knowledge on sweet spots and producibility thresholds at a recent Geosciences Technology Workshop on Unconventional Reservoir Quality.


The influence of moisture, temperature, coal rank, and differential enthalpy on the methane (CH4) and carbon dioxide (CO2) sorption capacity of coals of different rank has been investigated by using high-pressure sorption isotherms at 303, 318, and 333 K (CH4) and 318, 333, and 348 K (CO2), respectively. The variation of sorption capacity was studied as a function of burial depth of coal seams using the corresponding Langmuir parameters in combination with a geothermal gradient of 0.03 K/m and a normal hydrostatic pressure gradient. Taking the gas content corresponding to 100% gas saturation at maximum burial depth as a reference value, the theoretical CH4 saturation after the uplift of the coal seam was computed as a function of depth. According to these calculations, the change in sorption capacity caused by changing pressure, temperature conditions during uplift will lead consistently to high saturation values. Therefore, the commonly observed undersaturation of coal seams is most likely related to dismigration (losses into adjacent formations and atmosphere). Finally, we attempt to identify sweet spots for CO2-enhanced coalbed methane (CO2-ECBM) production. The CO2-ECBM is expected to become less effective with increasing depth because the CO2-to-CH4 sorption capacity ratio decreases with increasing temperature and pressure. Furthermore, CO2-ECBM efficiency will decrease with increasing maturity because of the highest sorption capacity ratio and affinity difference between CO2 and CH4 for low mature coals.


Sandstone pressures follow the hydrostatic gradient in Miocene strata of the Mad Dog field, deep-water Gulf of Mexico, whereas pore pressures in the adjacent mudstones track a trend from well to well that can be approximated by the total vertical stress gradient. The sandstone pressures within these strata are everywhere less than the bounding mudstone pore pressures, and the difference between them is proportional to the total vertical stress. The mudstone pressure is predicted from its porosity with an exponential porosity-versus-vertical effective stress relationship, where porosity is interpreted from wireline velocity. Sonic velocities in mudstones bounding the regional sandstones fall within a narrow range throughout the field from which we interpret their vertical effective stresses can be approximated as constant. We show how to predict sandstone and mudstone pore pressure in any offset well at Mad Dog given knowledge of the local total vertical stress. At Mad Dog, the approach is complicated by the extraordinary lateral changes in total vertical stress that are caused by changing bathymetry and the presence or absence of salt. A similar approach can be used in other subsalt fields. We suggest that pore pressures within mudstones can be systematically different from those of the nearby sandstones, and that this difference can be predicted. Well programs must ensure that the borehole pressure is not too low, which results in borehole closure in the mudstone intervals, and not too high, which can result in lost circulation to the reservoir intervals.


This article describes a 250-m (820-ft)-thick upper Eocene deep-water clastic succession. This succession is divided into two reservoir zones: the lower sandstone zone (LSZ) and the upper sandstone zone, separated by a package of pelitic rocks with variable thickness on the order of tens of meters. The application of sequence-stratigraphic methodology allowed the subdivision of this stratigraphic section into third-order systems tracts.

The LSZ is characterized by blocky and fining-upward beds on well logs, and includes interbedded shale layers of as much as 10 m (33 ft) thick. This zone reaches a maximum thickness of 150 m (492 ft) and fills a trough at least 4 km (2 mi) wide, underlain by an erosional surface. The lower part of this zone consists of coarse- to medium-grained sandstones with good vertical pressure communication. We interpret this unit as vertically and laterally amalgamated channel-fill deposits of high-density turbidity flows accumulated during late forced regression. The sandstones in the upper part of this trough are dominantly medium to fine grained and display an overall fining-upward trend. We interpret them as laterally amalgamated channel-fill deposits of lower density turbidity flows, relative to the ones in the lower part of the LSZ, accumulated during lowstand to early transgression.

The pelitic rocks that separate the two sandstone zones display variable thickness, from 35 to more than 100 m (115–>328 ft), indistinct seismic facies, and no internal markers on well logs, and consist of muddy diamictites with contorted shale rip-up clasts. This section is interpreted as cohesive debris flows and/or mass-transported slumps accumulated during late transgression.

The upper sandstone zone displays a weakly defined blocky well-log signature, where the proportion of sand is higher than 80%, and a jagged well-log signature, where the sand proportion is lower than 60%. The high proportions of sand are associated with a channelized geometry that is well delineated on seismic amplitude maps. Several depositional elements are identified within this zone, including leveed channels, crevasse channels, and splays associated with turbidity flows. This package is interpreted as the product of increased terrigenous sediment supply during highstand normal regression.


It is quite common for reservoir engineers to adjust the geological modelling without recoursing to the geologists by multiplying the porosity, the permeability, the anisotropy (kv/kh), the relative permeabilities, the well factors and many other parameters within their numerical world.


Petroleum exploration in deep water settings is resulting in the discovery of many giant fields in reservoirs that accumulated in large channel systems on the continental slope. The architecture of these reservoirs is exceedingly complex. In the face of multi-billion dollar costs, it is more important than ever before to accurately characterize these reservoirs.

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In-Person Training
Casper Wyoming United States 08 September, 2014 12 September, 2014 1513
Casper, Wyoming, United States
8-12 September 2014

Take advantage of this unique opportunity to learn all the aspects related to the understanding and modeling of fractured reservoirs. Attendees will take geologic concepts and use them in reservoir modeling through hands-on sessions devoted to the examination of outcrop, core and log data. They will use that information and a software to create 3D fractured reservoir models. Using actual Teapot Dome (Wyoming, USA) field data from the Tensleep and Niobrara Shale formations and a hands-on approach, the workshop allows the geoscientist to identify fractures and to construct predictive 3D fracture models that can be used to identify productive zones, plan wells and to create fracture porosity and permeability models for reservoir simulation.

Naples Italy 20 September, 2014 26 September, 2014 36
Naples, Italy
20-26 September 2014

The main part of the field seminar will focus on the description of the fractured carbonates and the extrapolation from the outcrop observations to the subsurface for building geologically plausible reservoir models.

Oklahoma City Oklahoma United States 25 September, 2014 25 September, 2014 10190
Oklahoma City, Oklahoma, United States
25 September 2014

This forum is an intensive one-day review by experts of the latest findings regarding the productive extent and producibility in the Granite Wash of Oklahoma and Texas, along with Pennsylvanian sand-producing horizons.

Houston Texas United States 11 November, 2014 11 November, 2014 10553
Houston, Texas, United States
11 November 2014

Through applied mineralogy, the student will learn what questions are relevant when formulating a work flow for a project, when evaluating real data, or when trying to figure out what might have “gone wrong” during a project.

Houston Texas United States 12 November, 2014 12 November, 2014 10555
Houston, Texas, United States
12 November 2014

This course is a practical approach to defining reservoir fluid and pressure related natural fracture generation and fracture property alteration in conventional and unconventional reservoirs.

Houston Texas United States 13 November, 2014 13 November, 2014 10566
Houston, Texas, United States
13 November 2014

This interdisciplinary course encompasses the fields of rock mechanics, structural geology and petroleum engineering to address a wide range of geomechanical problems that arise during the exploitation of oil and gas reservoirs.

Golden Colorado United States 17 November, 2014 19 November, 2014 10243
Golden, Colorado, United States
17-19 November 2014

Participants will learn how to be successful in utilizing the Three Forks in a stacked-pay, pad-drilling strategy when producing various Bakken members.

Kuwait City Kuwait 24 November, 2014 26 November, 2014 8560
Kuwait City, Kuwait
24-26 November 2014

Check the website as details develop.

Bogota Colombia 10 December, 2014 11 December, 2014 11015
14 February, 3000 14 February, 3000 7812
14 February, 3000 14 February, 3000 7816
14 February, 3000 14 February, 3000 7815
14 February, 3000 14 February, 3000 7813
Online Training
02 October, 2014 02 October, 2014 10593
2 October 2014
This course is ideal for individuals involved in Midland Basin exploration and development. Successful development of Wolfcamp shale oil relies on complex inter-relationships (ultimately interdependencies) within and between a wide variety of scientific disciplines, financial entities, and company partnerships. 
09 September, 2014 09 September, 2014 10591
9 September 2014
Water cut is a big factor in gauging the success of horizontal drilling in the Mississippi Lime Play (MLP). The contributing factors are related in part to the spectrum of producing lithofacies and reservoir quality encountered that varies laterally and vertically, sometimes dramatically.
10 September, 2013 10 September, 2013 1498
10 September 2013

The goal of this e-symposium is to review an important dimension in the ways geologist can build and update geological models using information from performance data.

26 September, 2013 26 September, 2013 1497
26 September 2013

The presentation will discuss key reservoir information and how to develop a predictive pressure model.

06 October, 2011 06 October, 2011 1479
6 October 2011

The e-symposium contains several case studies and log examples of bypassed pay and unconventional resources including Niobrara, Bakken, Marcellus, offshore GOM and others examples including processed log quality issues.

09 February, 2012 09 February, 2012 1477
9 February 2012

Projects in several shales will be discussed, including Marcellus, Eagle Ford, Haynesville, Fayetteville, Montney, and Barnett, as will several seismically-detectable drivers for success including lithofacies, stress, pre-existing fractures, and pore pressure.

08 November, 2012 08 November, 2012 1493
8 November 2012

This talk will present a brief overview of proppants followed by a comprehensive discussion of the major considerations that are driving proppant selection in these plays.

15 March, 2012 15 March, 2012 1484
15 March 2012

This e-symposium presents techniques for predicting pore pressure in seals by examining case studies from the Gulf of Mexico and incorporating the relationship between rocks, fluids, stress, and pressure.

10 November, 2011 10 November, 2011 1481
10 November 2011

This work investigates how heterogeneity can be defined and how we can quantify this term by describing a range of statistical heterogeneity (e.g. coefficient of variation and the Lorenz coefficient).

08 December, 2011 08 December, 2011 1480
8 December 2011

This e-symposium focuses on methods for predicting connectivity within clastic fluvial systems.

01 January, 2013 01 January, 9999 1459
1 January 2013 - 1 January 9999

There are more approximately 1,000 oil and gas fields in the world that have been classified as "giant," containing more than 500 million barrels of recoverable oil and /or 3 trillion cubic feet of gas.

17 March, 2011 17 March, 2011 1470
17 March 2011

This e-symposium will provide information on which tools, processes, and procedures all geoscientists, engineers, and technical professionals working in shale plays need to understand and implement.

21 October, 2010 21 October, 2010 1464
21 October 2010

This e-symposium covers how to conduct an interdisciplinary evaluation of mature fields to determine the best approach to recover remaining reserves.

25 January, 2011 25 January, 2011 1454
25 January 2011

This esymposium takes a close look at workflows associated with resource plays, and analyzes where integration must occur between disciplines, data, and workflows at all phases of the process.

22 October, 2009 22 October, 2009 1452
22 October 2009

This course can help you gain the ability to describe the complex and highly variable reservoirs, which are typified by complex internal heterogeneity.

21 May, 2009 21 May, 2009 1443
21 May 2009

This e-symposium introduces you to the practical benefits of thermal profiling for a variety of unconventional oil and gas projects, including tight gas sands, oil shale, low-gravity oil.

27 March, 2009 27 March, 2009 1435
27 March 2009

Join two GIS/geoscience experts Scott Sires and Gerry Bartz as they use information from the Teapot Dome Field in Wyoming (DOE/RMOTC program).

01 January, 2013 01 January, 9999 1473
1 January 2013 - 1 January 9999

Unconventional Resources is an online course that enables participants to learn about shale gas, shale oil and coalbed methane.

01 January, 2013 01 January, 9999 1472
1 January 2013 - 1 January 9999

This course introduces the learner to the fundamentals of shale gas, including current theories that explain its origin, and how to determine which reservoirs are commercially viable.

14 February, 3000 14 February, 3000 7817

Reservoir Characterization

Reservoir Characterization
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