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Petrophysics and Well Logs

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3416
 
The West Virginia Division of Energy is currently evaluating several deep saline formations in the Appalachian Basin of West Virginia that may be potential carbon dioxide (CO2) sequestration targets. The Silurian Newburg Sandstone play, developed in the 1960s and 1970s, primarily involved natural-gas production from reservoir rock with well-developed porosity and permeability. High initial pres-sures encountered in early wells in the Newburg indicated that the overlying Silurian Salina Formation provides a competent seal. Be-cause of the large number of CO2 point sources in the region and the favorable reservoir properties of the formation (including an esti-mated 300 bcf of natural-gas production), the Newburg Sandstone was evaluated for the potential geologic storage of CO2. Within the Newburg play, there are several primary fields separated geographi-cally and geologically by saltwater contacts and dry holes. Previous studies have determined the storage potential within these individual fields. This study shows that the Newburg is more suitable for small-scale injection tests instead of large-scale regional storage operations.
5726
 

Field analogs allow a better characterization of fracture networks to constrain naturally fractured reservoir models. In analogs, the origin, nature, geometry, and other attributes of fracture networks can be determined and can be related to the reservoir through the geodynamic history. In this article, we aim to determine the sedimentary and diagenetic controls on fracture patterns and the genetic correlation of fracture and diagenesis with tectonic and burial history. We targeted two outcrops of Barremian carbonates located on both limbs of the Nerthe anticline (southeastern France). We analyzed fracture patterns and rock facies as well as the tectonic, diagenetic, and burial history of both sites. Fracture patterns are determined from geometric, kinematic, and diagenetic criteria based on field and lab measurements. Fracture sequences are defined based on crosscutting and abutting relationships and compared with geodynamic history and subsidence curves. This analysis shows that fractures are organized in two close-to-perpendicular joint sets (i.e., mode I). Fracture average spacing is 50 cm (20 in.). Fracture size neither depends on fracture orientation nor is controlled by bed thickness. Neither mechanical stratigraphy nor fracture stratigraphy is observed at outcrop scale. Comparing fracture sequences and subsidence curves shows that fractures existed prior to folding and formed during early burial. Consequently, the Nerthe fold induced by the Pyrenean compression did not result in any new fracture initiation on the limbs of this fold. We assume that the studied Urgonian carbonates underwent early diagenesis, which conferred early brittle properties to the host rock.

5725
 

The Marcellus Shale is considered to be the largest unconventional shale-gas resource in the United States. Two critical factors for unconventional shale reservoirs are the response of a unit to hydraulic fracture stimulation and gas content. The fracture attributes reflect the geomechanical properties of the rocks, which are partly related to rock mineralogy. The natural gas content of a shale reservoir rock is strongly linked to organic matter content, measured by total organic carbon (TOC). A mudstone lithofacies is a vertically and laterally continuous zone with similar mineral composition, rock geomechanical properties, and TOC content. Core, log, and seismic data were used to build a three-dimensional (3-D) mudrock lithofacies model from core to wells and, finally, to regional scale. An artificial neural network was used for lithofacies prediction. Eight petrophysical parameters derived from conventional logs were determined as critical inputs. Advanced logs, such as pulsed neutron spectroscopy, with log-determined mineral composition and TOC data were used to improve and confirm the quantitative relationship between conventional logs and lithofacies. Sequential indicator simulation performed well for 3-D modeling of Marcellus Shale lithofacies. The interplay of dilution by terrigenous detritus, organic matter productivity, and organic matter preservation and decomposition affected the distribution of Marcellus Shale lithofacies distribution, which may be attributed to water depth and the distance to shoreline. The trend of normalized average gas production rate from horizontal wells supported our approach to modeling Marcellus Shale lithofacies. The proposed 3-D modeling approach may be helpful for optimizing the design of horizontal well trajectories and hydraulic fracture stimulation strategies.

5724
 

Size fractions (<4 and 0.4–1.0 μ) of Brent Group sandstones from the northern North Sea contain mostly illite-smectite mixed layers with kaolinite, whereas the same size fractions of Fulmar Formation sandstones from the south-central North Sea consist of illite-smectite mixed layers with minor chlorite. Transmission electron microscope observations show elongated illite laths or agglomerates consisting of small laths when larger individual laths are lacking.

The K-Ar data of the fractions less than 0.4 μm of Brent Group samples plot on two arrays in a 40Ar/36Ar vs. 40K/36Ar diagram that have isochron characteristics with ages of 76.5 ± 4.2 and 40.0 ± 1.5 Ma, and initial 40Ar/36Ar ratios of 253 ± 16 and 301 ± 18, respectively. For the Fulmar Formation samples, the data points of the fractions less than 0.2 and less than 0.4 μ also fit two isochrons with ages of 76.6 ± 1.4 and 47.9 ± 0.5 Ma and initial 40Ar/36Ar ratios of 359 ± 52 and 304 ± 2, respectively. Some of the coarser 0.4–1.0-μ fractions also plot on the two isochrons, but most plot above indicating the presence of detrital components more than 0.4 μ. The almost identical ages obtained from illite-type crystals of sandstones with different deposition ages that are located about 600 km (373 mi) apart record two simultaneous illitization episodes. These events were not induced by local burial conditions, but are related to episodic pressure and/or temperature increases in the studied reservoirs, probably induced by hydrocarbon injection. This interpretation is indirectly supported by notably different K-Ar illite ages from cores of a nearby reservoir at hydrostatic pressure.

Illite is not as well crystallized as expected for potential crystallization temperatures above 160°C measured by fluid-inclusion determinations. In both the northern and south-central North Sea, the two illite generations remain unaffected after crystallization despite continued burial, suggesting notably higher crystallization temperatures than those estimated from geothermal gradients. No recent illite crystallization or alteration is recorded in the K-Ar ages, despite a dramatic regional acceleration of the subsidence in the southern North Sea. ±

5723
 
Pore-volume reduction of sediments by plastic deformation during compaction and by cementation of grains has been evaluated for different proportions of ductile and hard grains. We represent the compaction behavior of grains with a purely geometric model, which uses the cooperative rearrangement algorithm to produce dense, random packings of partly interpenetrating spheres. We varied the fraction of grains assumed to be ductile and the radius of the rigid core of the ductile grains. The predicted relationship between the fraction of ductile grains in the sediment and the porosity after compaction agrees well with previously published experimental data in the literature. The radius of the rigid core of the ductile grains is an effective way to represent different kinds of ductile material, ranging from brittle (rigid radius gt0.9) to extremely ductile (rigid radius lt0.7). We simulated quartz cementation in our compacted rock by adding isopachous cement. Cement thickness was reduced on the smaller grains and increased on the larger grains to account for presumed export of pressure-dissolved material from finer grained regions and the import of material into coarser grained regions. These simulations yield descriptions of pore-scale geometry resulting from processes common in sandstones. Modeled pore geometry provides insight into transport properties of such rocks. For example, the models predict, to within a factor of five, the permeability of samples of tight-gas sandstones having little intragranular porosity.
144
 
Explorer Historical Highlight

Exploration for oil and gas in Saskatchewan was initiated in 1888 with the spudding of a 472-meter (1,548.5 feet) well near the settlement of Belle Plaine some 32 kilometers (20 miles) west of Regina.

116
 

Coming to a field near you – new technology that will reshape the oil and gas industry. When? Maybe sooner than you think.

5687
 

Using diverse geologic and geophysical data from recent exploration and development, and experimental results of analysis of gas content, gas capacity, and gas composition, this article discusses how geologic, structural, and hydrological factors determine the heterogeneous distribution of gas in the Weibei coalbed methane (CBM) field.

The coal rank of the Pennsylvanian no. 5 coal seam is mainly low-volatile bituminous and semianthracite. The total gas content is 2.69 to 16.15 m3/t (95.00–570.33 scf/t), and gas saturation is 26.0% to 93.2%. Burial coalification followed by tectonically driven hydrothermal activity controls not only thermal maturity, but also the quality and quantity of thermogenic gas generated from the coal.

Gas composition indicates that the CBM is dry and of dominantly thermogenic origin. The thermogenic gases have been altered by fractionation that may be related to subsurface water movement in the southern part of the study area.

Three gas accumulation models are identified: (1) gas diffusion and long-distance migration of thermogenic gases to no-flow boundaries for sorption and minor conventional trapping, (2) hydrodynamic trapping of gas in structural lows, and (3) gas loss by hydrodynamic flushing. The first two models are applicable for the formation of two CBM enrichment areas in blocks B3 and B4, whereas the last model explains extremely low gas content and gas saturation in block B5. The variable gas content, saturation, and accumulation characteristics are mainly controlled by these gas accumulation models.

5686
 

Sequence stratigraphy and coal cycles based on accommodation trends were investigated in the coal-bearing Lower Cretaceous Mannville Group in the Lloydminster heavy oil field, eastern Alberta. The study area is in a low accommodation setting on the cratonic margin of the Western Canada sedimentary basin. Geophysical log correlation of coal seams, shoreface facies, and the identification of incised valleys has produced a sequence-stratigraphic framework for petrographic data from 3 cored and 115 geophysical-logged wells. Maceral analysis, telovitrinite reflectance, and fluorescence measurements were taken from a total of 206 samples. Three terrestrial depositional environments were interpreted from the petrographic data: ombrotrophic mire coal, limnotelmatic mire coal, and carbonaceous shale horizons. Accommodation-based coal (wetting- and drying-upward) cycles represent trends in depositional environment shifts, and these cycles were used to investigate the development and preservation of the coal seams across the study area.

The low-accommodation strata are characterized by a high-frequency occurrence of significant surfaces, coal seam splitting, paleosol, and incised-valley development. Three sequence boundary unconformities are identified in only 20 m (66 ft) of strata. Coal cycle correlations illustrate that each coal seam in this study area was not produced by a single peat-accumulation episode but as an amalgamation of a series of depositional events. Complex relations between the Cummings and Lloydminster coal seams are caused by the lateral fragmentation of strata resulting from the removal of sediment by subaerial erosion or periods of nondeposition. Syndepositional faulting of the underlying basement rock changed local accommodation space and increased the complexity of the coal cycle development.

This study represents a low-accommodation example from a spectrum of stratigraphic studies that have been used to establish a terrestrial sequence-stratigraphic model. The frequency of changes in coal seam quality is an important control on methane distribution within coalbed methane reservoirs and resource calculations in coal mining. A depositional model based on the coal cycle correlations, as shown by this study, can provide coal quality prediction for coalbed methane exploration, reservoir completions, and coal mining.

5684
 
The fact that velocity models based on seismic reflection surveys commonly do not consider the near-surface geology necessitates filling the gap between the top of a velocity model and the surface of the Earth. In this study, we present a new workflow to build a shallow geologic model based exclusively on borehole data and corroborated by laboratory measurements. The study area is in Chemery (France), located at the southwestern border of the Paris Basin, where a large amount of borehole data is publicly available. The workflow starts with identifying lithologic interfaces in the boreholes and interpolating them between the boreholes. The three-dimensional (3-D) geometry of the lithologies then allows interpretation of the position, orientation, and offset of fault planes. Given the importance of the fault interpretation in the modeling process, a combination of different approaches is used to obtain the most reasonable structural framework. After creating a 3-D grid, the resulting 3-D structural model is populated with upscaled velocity logs from the boreholes, yielding the final near-surface P-wave velocity model. To better constrain the velocity model, we conducted laboratory measurements of P- and S-wave velocities in dry and water-saturated conditions on all lithologies in the model. The laboratory data were used to populate the 3-D near-surface model with VP/VS ratio values. The presented workflow accounts for one-dimensional borehole data and is much more iterative and time-consuming than workflows based on two-dimensional seismic sections. Nevertheless, the workflow results in a robust 3-D near-surface model allowing for structural interpretations and revealing the 3-D seismic velocity field.
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In-Person Training
Tulsa Oklahoma United States 07 October, 2014 09 October, 2014 1511
 
Tulsa, Oklahoma, United States
7-9 October 2014

Here is an introduction to the tools and techniques that geologists and geophysicists use to locate gas and oil, that drillers use to drill the wells and that petroleum engineers use to test and complete the wells and produce the gas and oil. Exercises throughout the course provide practical experience in well log correlation, contouring, interpretation of surface and subsurface, contoured maps, seismic interpretation, well log interpretation, and decline curve analysis.

Houston Texas United States 10 November, 2014 11 November, 2014 10487
 
Houston, Texas, United States
10-11 November 2014

This course summarizes the major advances and current controversies in dolomite research.

Houston Texas United States 10 November, 2014 10 November, 2014 10401
 
Houston, Texas, United States
10 November 2014

A one-day series of lectures covers the basic architecture of particulate sedimentary rocks, methods for petrologic characterization, grain assemblages, and diagenesis, including compaction, cementation, grain replacement, and fracturing. Examples of the nature and causes of reservoir quality variations in sandstones at low and high temperatures are provided with a focus on using the character of the primary grain assemblage as a predictive guide to what will happen in the subsurface.

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 10568
 
Houston, Texas, United States
12 November 2014

This course provides a rigorous overview of how and where organic-rich rocks are deposited, how they evolve into oil- and gas-generating source rocks, how the porosity systems evolve with thermal maturation, and the petrophysical properties of shale-gas and shale-liquid fine-grained reservoirs.

Houston Texas United States 13 November, 2014 13 November, 2014 10572
 
Houston, Texas, United States
13 November 2014

The course begins with a short review of the basic principles of carbonate well logging and goes on to detail the different carbonate pore types and the logging methods used to differentiate the various pore types and to determine their hydrocarbon productive potential.

Houston Texas United States 13 November, 2014 13 November, 2014 10379
 
Houston, Texas, United States
13 November 2014

This course is an introduction to the Bakken/Three Forks resource play.

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.

Houston Texas United States 02 December, 2014 04 December, 2014 1516
 
Houston, Texas, United States
2-4 December 2014

Here is an introduction to the tools and techniques that geologists and geophysicists use to locate gas and oil, that drillers use to drill the wells and that petroleum engineers use to test and complete the wells and produce the gas and oil. Exercises throughout the course provide practical experience in well log correlation, contouring, interpretation of surface and subsurface, contoured maps, seismic interpretation, well log interpretation, and decline curve analysis.

Bogotá, D. C. Colombia 10 December, 2014 11 December, 2014 11015
 
14 February, 3000 14 February, 3000 7816
 
14 February, 3000 14 February, 3000 7813
 
14 February, 3000 14 February, 3000 7812
 
14 February, 3000 14 February, 3000 7815
 
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. 
21 February, 2013 21 February, 2013 1495
 
21 February 2013

The course will review core data, petrophysical comparisons, rock physics modeling (including pseudo logs and mechanical properties).

07 June, 2012 07 June, 2012 1488
 
7 June 2012

Unger Field, discovered in1955, has produced 8.6 million barrels of oil from a thinly (several ft) bedded, locally cherty dolomite containing vuggy and intercrystalline porosity.

13 December, 2012 13 December, 2012 1494
 
13 December 2012

The course will review core data, petrophysical comparisons, rock physics modeling (including pseudo logs and mechanical properties).

31 October, 2012 31 October, 2012 1492
 
31 October 2012

This e-symposium will focus on how surface geochemical surveys and Downhole Geochemical Imaging technologies can be utilized jointly to directly characterize the composition of hydrocarbons vertically through the prospect section.

16 February, 2012 16 February, 2012 1483
 
16 February 2012

This presentation describes a proven workflow that uses a standard narrow azimuth 3D seismic, conventional logs, image logs and core data to build five key reservoir properties required for an optimal development of shale plays.

30 August, 2012 30 August, 2012 1489
 
30 August 2012

The entire Middle Pennsylvanian–to–top Precambrian basement (500 m) interval was cored in early 2011 in the BEREXCO Wellington KGS #1-32 well in Wellington Field, Sumner County, KS.

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.

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.

29 September, 2011 29 September, 2011 1478
 
29 September 2011

This study will focus in the combination of λρ – μρ inversion with clustering analysis techniques in order to discriminate brittle zones in the Barnett Shale.

24 October, 2013 24 October, 2013 1499
 
24 October 2013

This e-symposium will be introducing signal processing techniques as a means to maximize extracting geomechanical data from petrophysical logs.

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).

07 November, 2013 07 November, 2013 1500
 
7 November 2013

This e-symposium presentation places the interpretation of deep-water turbidites discernible in 3-D seismic inversion data within a geological context.

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.

25 August, 2011 25 August, 2011 1475
 
25 August 2011

This e-symposium provides highlights of the hydraulic fracturing mechanics, analysis, and design, and is derived from a two and one-half (2-1/2) day course which is designed for drilling, completion, production engineers, engineering technicians, geologists, well-site and completion supervisors, and managers, who desire to possess a comprehensive and integral knowledge of Hydraulic Fracturing.

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.

17 February, 2011 17 February, 2011 1469
 
17 February 2011

This presentation is designed for exploration/production geologists and geological managers or reservoir engineers.

25 March, 2010 25 March, 2010 1458
 
25 March 2010

The presentation describes a well established fracture modeling workflow that uses a standard 3D seismic, conventional logs, image logs and data from one core to build predictive 3D fracture models that are validated with blind wells.

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.

11 February, 2010 11 February, 2010 1441
 
11 February 2010

Gas hydrates, ice-like substances composed of water and gas molecules (methane, ethane, propane, etc.), occur in permafrost areas and in deep water marine environments.

14 February, 3000 14 February, 3000 7817
 
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