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Papers by gary citron

AAPG Bulletin, May 1, 2023

* Article based on a full paper published in the GCAGS Transactions (see footnote reference below... more * Article based on a full paper published in the GCAGS Transactions (see footnote reference below), which is available as part of the entire 2017 GCAGS Transactions volume via the GCAGS Bookstore at the Bureau of Economic Geology (www.beg.utexas.edu) or as an individual document via AAPG Datapages, Inc.

AAPG Bulletin, May 1, 2023

* Article based on a full paper published in the GCAGS Transactions (see footnote reference below... more * Article based on a full paper published in the GCAGS Transactions (see footnote reference below), which is available as part of the entire 2017 GCAGS Transactions volume via the GCAGS Bookstore at the Bureau of Economic Geology (www.beg.utexas.edu) or as an individual document via AAPG Datapages, Inc.

EGU General Assembly Conference Abstracts, May 1, 2014

EGU General Assembly Conference Abstracts, May 1, 2014

AAPG Bulletin, 2002

As many companies have come to appreciate the need for consistency in characterizing prospect ent... more As many companies have come to appreciate the need for consistency in characterizing prospect entries for a portfolio, they have also begun to harness the complimentary power that comes from calibrating estimates against actual results. Pre-drill efforts to standardize evaluations can often reveal overt examples of bias prior to portfolio selection. However, rigorous completion of the E&P evaluation process requires an element of performance tracking that arises from consistent post-drill audits of all exploration wells as well as significant development wells.

Both the Kelly Criterion and risk aversion using utility theory are methods that attempt to mitig... more Both the Kelly Criterion and risk aversion using utility theory are methods that attempt to mitigate the risk of gambler's ruin through capital management by suggesting working interest levels for each project. Utility theory uses an assigned risk tolerance and a natural log utility function to calculate the optimum working interest for a project. The modified Kelly method does not use a utility function but rather a geometric mean-based valuation derived from the ratio of the expected value to the net present value. This ratio, called the Kelly Criterion, is a guide for capital allocation to a project as the percent of the total capital available. When the total recommended cost of all the projects exceeds the budget, the combined portfolio is optimized by further adjusting the working interest using a linear programming technique, such as Excel’s ™ Solver. This optimization process was described by MacKay (1995) at a previous HEES Symposium (SPE 30043). The objective of this paper is to compare the procedure described by MacKay (1995) to a similar procedure using the modified Kelly method. The Kelly Criterion is currently used for financial investment decisions (Lee, 2006) and described in the book "Fortune’s Formula" by Poundstone (2005).

Journal of Petrology, Dec 24, 2018

Calc-alkaline plutons are the major crustal building blocks of continental margins, but are rarel... more Calc-alkaline plutons are the major crustal building blocks of continental margins, but are rarely exposed in oceanic island arcs. Two of the best examples are the 10kmwideHiddenBayandKagalaskaplutonsthatintrudeEocenemaficvolcanic−sedimentaryrocksonAdakandKagalaskaislandsinthecentralAleutianarc.TwentynewAr/ArandU/Pbages,coupledwithpublishedages,showthattheHiddenBayplutonwasintrudedinmultiplestagesfrom10 km wide Hidden Bay and Kagalaska plutons that intrude Eocene mafic volcanic-sedimentary rocks on Adak and Kagalaska islands in the central Aleutian arc. Twenty new Ar/Ar and U/Pb ages, coupled with published ages, show that the Hidden Bay pluton was intruded in multiple stages from 10kmwideHiddenBayandKagalaskaplutonsthatintrudeEocenemaficvolcanic−sedimentaryrocksonAdakandKagalaskaislandsinthecentralAleutianarc.TwentynewAr/ArandU/Pbages,coupledwithpublishedages,showthattheHiddenBayplutonwasintrudedinmultiplestagesfrom34Á6 to 30Á9 Ma, whereas the Kagalaska pluton was intruded at 14Ma.Theplutonslargelyconsistofmedium−tohigh−K2Ohornblende−bearingcumulatediorite(53−55wt14 Ma. The plutons largely consist of medium-to high-K 2 O hornblende-bearing cumulate diorite (53-55 wt % SiO 2) and hornblende-biotite granodiorite (57-64 wt %), with lesser amounts of gabbro (50-52 wt % SiO 2), leucogranodiorite (67-69 wt % SiO 2) and aplite (76-77 wt % SiO 2) that can generally be linked to each other by crystal fractionation. The compositions of these plutons are generally similar to those of continental plutons, except for more oceanic-like large ion lithophile element and isotopic signatures (87 Sr/ 86 Sr ¼ 0Á703-0Á7033; ENd ¼ 9Á4-7Á7) that reflect oceanic-rather than continental-type crustal contaminants. Chemical similarities between the Hidden Bay homogeneous gabbros and high-Al basalts in Adak Pleistocene-Holocene volcanoes indicate little temporal evolution in the general character of the mantle-derived basalts. Rather than a unique arc setting and distinctive magmas, formation of the Aleutian calc-alkaline plutons seems to require a sufficient crustal thickness (14Ma.Theplutonslargelyconsistofmedium−tohigh−K2Ohornblende−bearingcumulatediorite(53−55wt37 km) and a high enough water content to stabilize pargasitic hornblende amphibole in a relatively closed magma system that favors increasing K, Ti and H 2 O at the end of a magmatic cycle. This termination of magmatism coincides with a northward migration of the magmatic front that is inferred to be associated with fore-arc subduction erosion. In accord with Adak region crustal architecture based on seismic data, crystallization models for the plutons suggest that mantle-generated hydrous arc basalts fractionated olivine and clinopyroxene in the lower crust to form high-Al basaltic composition magmas that rose into the mid-crust, where gabbro and diorite crystallized to form the magmas that buoyantly rose into the upper crust and crystallized to form the volumetrically dominant granodiorite (58-63 wt % SiO 2). The most important temporal changes in chemistry can be explained by fore-arc crust incorporated into the mantle wedge by fore-arc subduction erosion creating 'adakitic' signatures at times of northward arc migration and a change to a more continental subducted sediment component at the time of Plio-Pleistocene glaciation.

AGU Fall Meeting Abstracts, Dec 1, 2016

* Article based on a full paper published in the GCAGS Transactions (see footnote reference below... more * Article based on a full paper published in the GCAGS Transactions (see footnote reference below), which is available as part of the entire 2016 GCAGS Transactions volume via the GCAGS Bookstore at the Bureau of Economic Geology (www.beg.utexas.edu) or as an individual document via AAPG Datapages, Inc.

The leading edge, Aug 1, 2001

Gulf Coast explorers are now frequently faced with assessing multiple-zone prospects. Some or all... more Gulf Coast explorers are now frequently faced with assessing multiple-zone prospects. Some or all of these zones are often incorrectly described as "direct hydrocarbon indicators". In this paper we deal with best practices of consistency and calibration to ensure appropriate prospect valuation of such cases. Multiple-zone prospects need to be evaluated probabilistically on a zone-by-zone basis. When a zone is identified as "amplitude-bearing", a series of questions about the anomaly helps address the appropriate range of uncertainty associated with productive area, net pay and recovery factor. Discussion should focus on the anomaly's (1) strength and polarity relative to known lithologic sequences and its presumed downdip water leg, (2) conformance relative to downdip structural contours, (3) AVO, and (4) fit to the depositional model. Results of drilled amplitude targets can be evaluated in the same vein, producing a matrix populated by data that can serve as reality checks on the assigned Geological Chance of Success, Pg. Evaluation schemes should not necessarily equate "amplitude anomaly" with "direct hydrocarbon indicator" because the latter implies more certainty of hydrocarbon presence and a much narrower range of outcomes that is often not warranted. After each zone's parameter range is set and assessed for Pg, then a cogent discussion of the geologic phenomena that may produce dependency among zone ensues. Once the nature and amount of dependence has been assessed, the reserve distributions can be combined via Monte Carlo methods. Any commercial truncation is reserved for the entire prospect rather than the individual zones.

AAPG Bulletin, Oct 1, 2008

Geological Society, London, Special Publications, 2006

Global exploration over the past decade has been characterized by fewer large fields discovered r... more Global exploration over the past decade has been characterized by fewer large fields discovered relative to the previous decades, while the commercial success rate has remained constant at about 25%. Amidst the shrinking resource base, demand remains robust, thus signifying the clear need for enhanced efficiency in the deliberate search for stratigraphic traps.Recent analyst reports substantiate the need for a re-invigorated exploration role to profitably replace production, rather than an over-reliance on acquisitions.To meet this need, explorers are required to serve three main roles which, at times, may conflict with each other. First, they must be creative, to conceptualize and envision subtle traps. Second, they must measure them in a responsible, professional fashion for the benefit of the shareholders. Third, they must communicate the uncertainty and probability aspects associated with their characterization of the opportunity in a clear fashion to facilitate more informed decision-making and more predictive portfolio management.We attempt to facilitate and enhance the renewal of the exploration role with lessons we have learned from the fields of systematic risk analysis of geologic trends, also known as play analysis, lessons from economics and risk aversion, and lessons from the analysis of complex traps.Having observed firsthand how leading E&P companies are conducting their global exploration programs, we want to begin by reviewing some key aspects of creativity and measurement needed for ‘new-play’ exploration and, in particular, how it applies to the search for stratigraphic traps.Starting with some background perspective on the exploration business, we focus on the importance and subsequent reaffirmation of the exploration role, and conclude with a number of lessons, or insights, to take away that we hope will inspire and assist in their deliberate searches for stratigraphic traps. These insights represent best practices we have observed in client companies, on creativity and opportunity-measurement in the pursuit of viable, profitable exploration opportunities.Our information regarding the status of exploration comes courtesy of some global databases and some recently published analyst reports. These published reports support our contention that the exploration role needs to continue its renewal, and contribute more significantly to profitable production replacement relative to property acquisitions.The path towards profitable production replacement often begins with the creativity provided by the exploration team associated with evaluating or generating new play concepts. Creativity at the regional level benefits by approaching subtle trap exploration through probabilistic play analysis. In this context, regional geological analyses can better pinpoint the critical elements, and systematically search for the footprint of active migration pathways provided by hydrocarbon shows. Explorers should take full advantage of thought-experiments that pose both outlandishly successful and embarrassingly meagre results (including failure) to promote characterization of the full range of outcomes consistent with the inherent uncertainty, and the likelihood of achieving various success states.These regional efforts can then be integrated with the appropriate discount rate for a company’s economic valuation system. We also share some lessons learned regarding the business realities of a company’s dry hole tolerance to better plan for interim learnings and exit strategies. Similar considerations and open discussion of a company’s risk tolerance can lead to more appropriate diversification in the critical plays needed to achieve a business plan.We also review chance-dependency issues among prospects and leads in plays. In particular, we note that measurement of subtle traps often requires special attention to the geological phenomena that indicate internal parameter dependencies and changes in the probability profile that need to be perceived, calculated and communicated for complete characterization of given opportunities. The more consistency and calibration that is achieved in prospect characterizations, the more predictable a company’s portfolio will become.

All Days, Jun 8, 2009

Many firms are pursuing unconventional resource opportunities across the globe as a low risk vehi... more Many firms are pursuing unconventional resource opportunities across the globe as a low risk vehicle for growth. Unfortunately, not all resource plays have met the expectations of this low risk model. Some opportunities are very product price dependent and others are both price and technology dependent. This paper provides an overview of the North American industry's use of statistically based production and EUR type curves to assess new opportunities and ongoing developments. This paper highlights an alternative methodology for the selection of future unconventional resource opportunities based on their corporate definition of materiality and the use of analog production type curves. This methodology focuses on appropriate production type curves rather than reservoir models for tight gas sands and shale gas opportunities. Examples of production type curves will be presented to demonstrate the need to align these curves to the geological facies, the well type (vertical versus horizontal), and the completion technology (fracture stimulation size, fracture fluids, and the number of fracture stages). The appropriate selection from the myriad of unconventional resource opportunities available is often a critical component to achieving corporate goals. Pick the wrong opportunity and even with superb execution, the returns are limited. Selecting the right unconventional resource opportunity enhances your probability to please shareholders. The methodology is similar, yet unique from traditional basin analysis in its use of Common Risk Segment (aka ‘traffic light') maps and production type curves versus a range of reserves in a prospect.

AAPG Bulletin, Apr 1, 2021

Journal of Geophysical Research, 1982

The tectonic position of Aleutian arc volcanic centers and their magmatic differentiation trends ... more The tectonic position of Aleutian arc volcanic centers and their magmatic differentiation trends (calc-alkaline or tholeiitic) appear to correlate. From• 160øW to 175øE, the volcanoes form four major arc segments that coincide with earthquake aftershock zones and major geographic features on both the upper and lower plates. The tholeiitic volcanoes are large, primarily basaltic centers that occur between or at the end of segments where magmas can more easily reach the surface and undergo shallow, closed system differentiation. The calc-alkaline volcanoes are smaller, more andesitic centers that occur in the middle of segments where transit through the upper plate is apparently more difficult. Differentiation is deeper and the intrusive to extrusive ratios are higher than in the tholeiitic centers. The chemistry of the least differentiated basalts at both types of centers is similar and suggests a common parent magma, probably derived from mantle peridotite. Conditions for the derivation of the two trends through crystal fractionation support the proposed model. The tholeiitic magmas show characteristics (i.e., no hydrous phenocrysts, Fe enrichment trend, parallel REE patterns, vitrophyric andesites and dacites) consistent with low-pressure, hightemperature crystallization in large shallow magma chambers. The calc-alkaline magmas show characteristics (i.e., some hydrous phenocrysts, no Fe enrichment trend, nonparallel rare earth patterns, porphyritic lavas) consistent with higher pressure and lower temperature of crystallization than the tholeiitic series. Tertiary plutons also show both calc-alkaline and tholeiitic trends and appear to be chemically similar to the Quaternary volcanoes. The larger plutons are calc-alkaline and probably represent the extensive (100 km 2) magma chambers of the small calc-alkaline volcanoes. The small, shallow tholeiitic plutons complement the large tholeiitic volcanoes and reflect the greater percent of extrusive rocks in the tholeiitic series.

AAPG Bulletin, Dec 1, 2022

Developments in Geotectonics, 1979

Abstract Examination of two lines of repeated leveling in North Carolina and Georgia reveals 1. (... more Abstract Examination of two lines of repeated leveling in North Carolina and Georgia reveals 1. (1) apparent uplift at the Blue Ridge-Piedmont physiographic boundary (the AtlanticGulf drainage divide) relative to the Atlantic Coastal Plain on the east and the Valley and Ridge province to the west; and 2. (2) large tilts over short baselines superimposed upon the regional pattern in the vicinity of the nearby Blue Ridge—Piedmont geologic boundary (the Brevard fault zone). In the North Carolina profile a very pronounced correlation between topography and movement suggests possible systematic leveling error, but the observed movements appear to be larger than those normally attributed to leveling error. Thus, either refraction or rod errors are larger than expected, or the movement is real and strongly correlates with topography along this portion of the leveling line. Anomalously high stream-gradients over both resistant and nonresistant lithologies are found around the drainage divide in North Carolina, and may be associated with the relative uplift inferred from releveling. The drainage divide in Georgia, also characterized by relative uplift on the movement profile, approximately separates two different types of stream patterns. In both cases evidence presented here suggests that stream morphology may be responding to contemporary deformation as implied by the observed elevation changes. The relative uplift in North Carolina also correlates with a positive Bouguer gravity anomaly of 30–40 mGal in the midst of the regional Blue Ridge gravity low, although the significance of the correlation is unclear. The close spatial correspondence between the zone of maximum uplift and the drainage divide suggests that the vertical movements and geomorphic anomalies may result from the same mechanism, although the nature of such is unclear. One possible mechanism could be displacement at depth along the nearby Brevard zone. However, on the basis of dislocation modeling it appears that the geodetic observations cannot be adequately explained by surface deformation associated with any simple models of slip on the Brevard zone.

AAPG Bulletin, May 1, 2023

* Article based on a full paper published in the GCAGS Transactions (see footnote reference below... more * Article based on a full paper published in the GCAGS Transactions (see footnote reference below), which is available as part of the entire 2017 GCAGS Transactions volume via the GCAGS Bookstore at the Bureau of Economic Geology (www.beg.utexas.edu) or as an individual document via AAPG Datapages, Inc.

AAPG Bulletin, May 1, 2023

* Article based on a full paper published in the GCAGS Transactions (see footnote reference below... more * Article based on a full paper published in the GCAGS Transactions (see footnote reference below), which is available as part of the entire 2017 GCAGS Transactions volume via the GCAGS Bookstore at the Bureau of Economic Geology (www.beg.utexas.edu) or as an individual document via AAPG Datapages, Inc.

EGU General Assembly Conference Abstracts, May 1, 2014

EGU General Assembly Conference Abstracts, May 1, 2014

AAPG Bulletin, 2002

As many companies have come to appreciate the need for consistency in characterizing prospect ent... more As many companies have come to appreciate the need for consistency in characterizing prospect entries for a portfolio, they have also begun to harness the complimentary power that comes from calibrating estimates against actual results. Pre-drill efforts to standardize evaluations can often reveal overt examples of bias prior to portfolio selection. However, rigorous completion of the E&P evaluation process requires an element of performance tracking that arises from consistent post-drill audits of all exploration wells as well as significant development wells.

Both the Kelly Criterion and risk aversion using utility theory are methods that attempt to mitig... more Both the Kelly Criterion and risk aversion using utility theory are methods that attempt to mitigate the risk of gambler's ruin through capital management by suggesting working interest levels for each project. Utility theory uses an assigned risk tolerance and a natural log utility function to calculate the optimum working interest for a project. The modified Kelly method does not use a utility function but rather a geometric mean-based valuation derived from the ratio of the expected value to the net present value. This ratio, called the Kelly Criterion, is a guide for capital allocation to a project as the percent of the total capital available. When the total recommended cost of all the projects exceeds the budget, the combined portfolio is optimized by further adjusting the working interest using a linear programming technique, such as Excel’s ™ Solver. This optimization process was described by MacKay (1995) at a previous HEES Symposium (SPE 30043). The objective of this paper is to compare the procedure described by MacKay (1995) to a similar procedure using the modified Kelly method. The Kelly Criterion is currently used for financial investment decisions (Lee, 2006) and described in the book "Fortune’s Formula" by Poundstone (2005).

Journal of Petrology, Dec 24, 2018

Calc-alkaline plutons are the major crustal building blocks of continental margins, but are rarel... more Calc-alkaline plutons are the major crustal building blocks of continental margins, but are rarely exposed in oceanic island arcs. Two of the best examples are the 10kmwideHiddenBayandKagalaskaplutonsthatintrudeEocenemaficvolcanic−sedimentaryrocksonAdakandKagalaskaislandsinthecentralAleutianarc.TwentynewAr/ArandU/Pbages,coupledwithpublishedages,showthattheHiddenBayplutonwasintrudedinmultiplestagesfrom10 km wide Hidden Bay and Kagalaska plutons that intrude Eocene mafic volcanic-sedimentary rocks on Adak and Kagalaska islands in the central Aleutian arc. Twenty new Ar/Ar and U/Pb ages, coupled with published ages, show that the Hidden Bay pluton was intruded in multiple stages from 10kmwideHiddenBayandKagalaskaplutonsthatintrudeEocenemaficvolcanic−sedimentaryrocksonAdakandKagalaskaislandsinthecentralAleutianarc.TwentynewAr/ArandU/Pbages,coupledwithpublishedages,showthattheHiddenBayplutonwasintrudedinmultiplestagesfrom34Á6 to 30Á9 Ma, whereas the Kagalaska pluton was intruded at 14Ma.Theplutonslargelyconsistofmedium−tohigh−K2Ohornblende−bearingcumulatediorite(53−55wt14 Ma. The plutons largely consist of medium-to high-K 2 O hornblende-bearing cumulate diorite (53-55 wt % SiO 2) and hornblende-biotite granodiorite (57-64 wt %), with lesser amounts of gabbro (50-52 wt % SiO 2), leucogranodiorite (67-69 wt % SiO 2) and aplite (76-77 wt % SiO 2) that can generally be linked to each other by crystal fractionation. The compositions of these plutons are generally similar to those of continental plutons, except for more oceanic-like large ion lithophile element and isotopic signatures (87 Sr/ 86 Sr ¼ 0Á703-0Á7033; ENd ¼ 9Á4-7Á7) that reflect oceanic-rather than continental-type crustal contaminants. Chemical similarities between the Hidden Bay homogeneous gabbros and high-Al basalts in Adak Pleistocene-Holocene volcanoes indicate little temporal evolution in the general character of the mantle-derived basalts. Rather than a unique arc setting and distinctive magmas, formation of the Aleutian calc-alkaline plutons seems to require a sufficient crustal thickness (14Ma.Theplutonslargelyconsistofmedium−tohigh−K2Ohornblende−bearingcumulatediorite(53−55wt37 km) and a high enough water content to stabilize pargasitic hornblende amphibole in a relatively closed magma system that favors increasing K, Ti and H 2 O at the end of a magmatic cycle. This termination of magmatism coincides with a northward migration of the magmatic front that is inferred to be associated with fore-arc subduction erosion. In accord with Adak region crustal architecture based on seismic data, crystallization models for the plutons suggest that mantle-generated hydrous arc basalts fractionated olivine and clinopyroxene in the lower crust to form high-Al basaltic composition magmas that rose into the mid-crust, where gabbro and diorite crystallized to form the magmas that buoyantly rose into the upper crust and crystallized to form the volumetrically dominant granodiorite (58-63 wt % SiO 2). The most important temporal changes in chemistry can be explained by fore-arc crust incorporated into the mantle wedge by fore-arc subduction erosion creating 'adakitic' signatures at times of northward arc migration and a change to a more continental subducted sediment component at the time of Plio-Pleistocene glaciation.

AGU Fall Meeting Abstracts, Dec 1, 2016

* Article based on a full paper published in the GCAGS Transactions (see footnote reference below... more * Article based on a full paper published in the GCAGS Transactions (see footnote reference below), which is available as part of the entire 2016 GCAGS Transactions volume via the GCAGS Bookstore at the Bureau of Economic Geology (www.beg.utexas.edu) or as an individual document via AAPG Datapages, Inc.

The leading edge, Aug 1, 2001

Gulf Coast explorers are now frequently faced with assessing multiple-zone prospects. Some or all... more Gulf Coast explorers are now frequently faced with assessing multiple-zone prospects. Some or all of these zones are often incorrectly described as "direct hydrocarbon indicators". In this paper we deal with best practices of consistency and calibration to ensure appropriate prospect valuation of such cases. Multiple-zone prospects need to be evaluated probabilistically on a zone-by-zone basis. When a zone is identified as "amplitude-bearing", a series of questions about the anomaly helps address the appropriate range of uncertainty associated with productive area, net pay and recovery factor. Discussion should focus on the anomaly's (1) strength and polarity relative to known lithologic sequences and its presumed downdip water leg, (2) conformance relative to downdip structural contours, (3) AVO, and (4) fit to the depositional model. Results of drilled amplitude targets can be evaluated in the same vein, producing a matrix populated by data that can serve as reality checks on the assigned Geological Chance of Success, Pg. Evaluation schemes should not necessarily equate "amplitude anomaly" with "direct hydrocarbon indicator" because the latter implies more certainty of hydrocarbon presence and a much narrower range of outcomes that is often not warranted. After each zone's parameter range is set and assessed for Pg, then a cogent discussion of the geologic phenomena that may produce dependency among zone ensues. Once the nature and amount of dependence has been assessed, the reserve distributions can be combined via Monte Carlo methods. Any commercial truncation is reserved for the entire prospect rather than the individual zones.

AAPG Bulletin, Oct 1, 2008

Geological Society, London, Special Publications, 2006

Global exploration over the past decade has been characterized by fewer large fields discovered r... more Global exploration over the past decade has been characterized by fewer large fields discovered relative to the previous decades, while the commercial success rate has remained constant at about 25%. Amidst the shrinking resource base, demand remains robust, thus signifying the clear need for enhanced efficiency in the deliberate search for stratigraphic traps.Recent analyst reports substantiate the need for a re-invigorated exploration role to profitably replace production, rather than an over-reliance on acquisitions.To meet this need, explorers are required to serve three main roles which, at times, may conflict with each other. First, they must be creative, to conceptualize and envision subtle traps. Second, they must measure them in a responsible, professional fashion for the benefit of the shareholders. Third, they must communicate the uncertainty and probability aspects associated with their characterization of the opportunity in a clear fashion to facilitate more informed decision-making and more predictive portfolio management.We attempt to facilitate and enhance the renewal of the exploration role with lessons we have learned from the fields of systematic risk analysis of geologic trends, also known as play analysis, lessons from economics and risk aversion, and lessons from the analysis of complex traps.Having observed firsthand how leading E&P companies are conducting their global exploration programs, we want to begin by reviewing some key aspects of creativity and measurement needed for ‘new-play’ exploration and, in particular, how it applies to the search for stratigraphic traps.Starting with some background perspective on the exploration business, we focus on the importance and subsequent reaffirmation of the exploration role, and conclude with a number of lessons, or insights, to take away that we hope will inspire and assist in their deliberate searches for stratigraphic traps. These insights represent best practices we have observed in client companies, on creativity and opportunity-measurement in the pursuit of viable, profitable exploration opportunities.Our information regarding the status of exploration comes courtesy of some global databases and some recently published analyst reports. These published reports support our contention that the exploration role needs to continue its renewal, and contribute more significantly to profitable production replacement relative to property acquisitions.The path towards profitable production replacement often begins with the creativity provided by the exploration team associated with evaluating or generating new play concepts. Creativity at the regional level benefits by approaching subtle trap exploration through probabilistic play analysis. In this context, regional geological analyses can better pinpoint the critical elements, and systematically search for the footprint of active migration pathways provided by hydrocarbon shows. Explorers should take full advantage of thought-experiments that pose both outlandishly successful and embarrassingly meagre results (including failure) to promote characterization of the full range of outcomes consistent with the inherent uncertainty, and the likelihood of achieving various success states.These regional efforts can then be integrated with the appropriate discount rate for a company’s economic valuation system. We also share some lessons learned regarding the business realities of a company’s dry hole tolerance to better plan for interim learnings and exit strategies. Similar considerations and open discussion of a company’s risk tolerance can lead to more appropriate diversification in the critical plays needed to achieve a business plan.We also review chance-dependency issues among prospects and leads in plays. In particular, we note that measurement of subtle traps often requires special attention to the geological phenomena that indicate internal parameter dependencies and changes in the probability profile that need to be perceived, calculated and communicated for complete characterization of given opportunities. The more consistency and calibration that is achieved in prospect characterizations, the more predictable a company’s portfolio will become.

All Days, Jun 8, 2009

Many firms are pursuing unconventional resource opportunities across the globe as a low risk vehi... more Many firms are pursuing unconventional resource opportunities across the globe as a low risk vehicle for growth. Unfortunately, not all resource plays have met the expectations of this low risk model. Some opportunities are very product price dependent and others are both price and technology dependent. This paper provides an overview of the North American industry's use of statistically based production and EUR type curves to assess new opportunities and ongoing developments. This paper highlights an alternative methodology for the selection of future unconventional resource opportunities based on their corporate definition of materiality and the use of analog production type curves. This methodology focuses on appropriate production type curves rather than reservoir models for tight gas sands and shale gas opportunities. Examples of production type curves will be presented to demonstrate the need to align these curves to the geological facies, the well type (vertical versus horizontal), and the completion technology (fracture stimulation size, fracture fluids, and the number of fracture stages). The appropriate selection from the myriad of unconventional resource opportunities available is often a critical component to achieving corporate goals. Pick the wrong opportunity and even with superb execution, the returns are limited. Selecting the right unconventional resource opportunity enhances your probability to please shareholders. The methodology is similar, yet unique from traditional basin analysis in its use of Common Risk Segment (aka ‘traffic light') maps and production type curves versus a range of reserves in a prospect.

AAPG Bulletin, Apr 1, 2021

Journal of Geophysical Research, 1982

The tectonic position of Aleutian arc volcanic centers and their magmatic differentiation trends ... more The tectonic position of Aleutian arc volcanic centers and their magmatic differentiation trends (calc-alkaline or tholeiitic) appear to correlate. From• 160øW to 175øE, the volcanoes form four major arc segments that coincide with earthquake aftershock zones and major geographic features on both the upper and lower plates. The tholeiitic volcanoes are large, primarily basaltic centers that occur between or at the end of segments where magmas can more easily reach the surface and undergo shallow, closed system differentiation. The calc-alkaline volcanoes are smaller, more andesitic centers that occur in the middle of segments where transit through the upper plate is apparently more difficult. Differentiation is deeper and the intrusive to extrusive ratios are higher than in the tholeiitic centers. The chemistry of the least differentiated basalts at both types of centers is similar and suggests a common parent magma, probably derived from mantle peridotite. Conditions for the derivation of the two trends through crystal fractionation support the proposed model. The tholeiitic magmas show characteristics (i.e., no hydrous phenocrysts, Fe enrichment trend, parallel REE patterns, vitrophyric andesites and dacites) consistent with low-pressure, hightemperature crystallization in large shallow magma chambers. The calc-alkaline magmas show characteristics (i.e., some hydrous phenocrysts, no Fe enrichment trend, nonparallel rare earth patterns, porphyritic lavas) consistent with higher pressure and lower temperature of crystallization than the tholeiitic series. Tertiary plutons also show both calc-alkaline and tholeiitic trends and appear to be chemically similar to the Quaternary volcanoes. The larger plutons are calc-alkaline and probably represent the extensive (100 km 2) magma chambers of the small calc-alkaline volcanoes. The small, shallow tholeiitic plutons complement the large tholeiitic volcanoes and reflect the greater percent of extrusive rocks in the tholeiitic series.

AAPG Bulletin, Dec 1, 2022

Developments in Geotectonics, 1979

Abstract Examination of two lines of repeated leveling in North Carolina and Georgia reveals 1. (... more Abstract Examination of two lines of repeated leveling in North Carolina and Georgia reveals 1. (1) apparent uplift at the Blue Ridge-Piedmont physiographic boundary (the AtlanticGulf drainage divide) relative to the Atlantic Coastal Plain on the east and the Valley and Ridge province to the west; and 2. (2) large tilts over short baselines superimposed upon the regional pattern in the vicinity of the nearby Blue Ridge—Piedmont geologic boundary (the Brevard fault zone). In the North Carolina profile a very pronounced correlation between topography and movement suggests possible systematic leveling error, but the observed movements appear to be larger than those normally attributed to leveling error. Thus, either refraction or rod errors are larger than expected, or the movement is real and strongly correlates with topography along this portion of the leveling line. Anomalously high stream-gradients over both resistant and nonresistant lithologies are found around the drainage divide in North Carolina, and may be associated with the relative uplift inferred from releveling. The drainage divide in Georgia, also characterized by relative uplift on the movement profile, approximately separates two different types of stream patterns. In both cases evidence presented here suggests that stream morphology may be responding to contemporary deformation as implied by the observed elevation changes. The relative uplift in North Carolina also correlates with a positive Bouguer gravity anomaly of 30–40 mGal in the midst of the regional Blue Ridge gravity low, although the significance of the correlation is unclear. The close spatial correspondence between the zone of maximum uplift and the drainage divide suggests that the vertical movements and geomorphic anomalies may result from the same mechanism, although the nature of such is unclear. One possible mechanism could be displacement at depth along the nearby Brevard zone. However, on the basis of dislocation modeling it appears that the geodetic observations cannot be adequately explained by surface deformation associated with any simple models of slip on the Brevard zone.