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Knut Heggland - One of the best experts on this subject based on the ideXlab platform.
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Volumes before and after exploration drilling: results from the project: Evaluation of Norwegian Wildcat Wells (Article 2)
Norwegian Petroleum Society Special Publications, 2007Co-Authors: Lars Fosvold, Mark Thomsen, Mike L. Brown, Lars Kullerud, Kari Ofstad, Knut HegglandAbstract:In this study historical post-drill hydrocarbon pore volumes and input volumetric parameters have been compared with the most likely pre-drill prospect volumes and parameters in order to investigate how well the industry has predicted discovery sizes. The study shows that the hydrocarbon industry operating on the Norwegian Continental Shelf has more or less consistently overestimated hydrocarbon volumes. There are, however, indications that the industry's predictions on average are somewhat better in regions of longer exploration and drilling history. Still, one cannot demonstrate clear differences between highly explored versus less explored areas in the ability to make better volumetric predictions for a particular prospect. The variability in bulk rock volume prediction errors is clearly the most important factor when explaining the differences in hydrocarbon pore volume pre- and post-drill.
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probability of discovery and the reasons for dry Wells results from the project evaluation of norwegian Wildcat Wells article 3
Norwegian Petroleum Society Special Publications, 2000Co-Authors: Kari Ofstad, Lars Kullerud, Audun Ovretveit, Knut HegglandAbstract:The reasons for dry prospects reported by the oil companies in the project ‘Evaluation of Norwegian Wildcat Wells’ are compared with the probabilities for trap, charge and reservoir predicted prior to drilling. A comparison of the pre-drill probability assessment and results for the different probability factors has been performed, in addition to analysing the discovery probability by year, regions, plays, trap types, 2D and 3D seismic, in-place hydrocarbon volumes and the distance to nearest well. The results from the study show that lack of lateral seal, reservoir and migration were reported as the main reasons for dry prospects. On average the predicted discovery probability was slightly pessimistic, 23%, but fairly close to the actual discovery rate when the small technical discoveries are excluded, which is 27%. The results show that the petroleum explorationists were too pessimistic in evaluating trap probability and, to a lesser extent, charge and reservoir probabilities. Variation in discovery rate by year, regions and plays is only to some extent reflected in the pre-drill evaluation of the discovery probability. The results show that the discovery rate is highest in mature exploration areas within established plays. There is an apparently slightly higher discovery rate for prospects drilled on 3D seismic compared to 2D in the years 1990 to 1997. The results show that there is a strong inverse correlation between the discovery rate and the distance to the nearest well and a significant inverse correlation between the discovery rate and the predicted volumes of the prospects, but this is not clearly reflected when discovery probability is estimated.
Kari Ofstad - One of the best experts on this subject based on the ideXlab platform.
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Volumes before and after exploration drilling: results from the project: Evaluation of Norwegian Wildcat Wells (Article 2)
Norwegian Petroleum Society Special Publications, 2007Co-Authors: Lars Fosvold, Mark Thomsen, Mike L. Brown, Lars Kullerud, Kari Ofstad, Knut HegglandAbstract:In this study historical post-drill hydrocarbon pore volumes and input volumetric parameters have been compared with the most likely pre-drill prospect volumes and parameters in order to investigate how well the industry has predicted discovery sizes. The study shows that the hydrocarbon industry operating on the Norwegian Continental Shelf has more or less consistently overestimated hydrocarbon volumes. There are, however, indications that the industry's predictions on average are somewhat better in regions of longer exploration and drilling history. Still, one cannot demonstrate clear differences between highly explored versus less explored areas in the ability to make better volumetric predictions for a particular prospect. The variability in bulk rock volume prediction errors is clearly the most important factor when explaining the differences in hydrocarbon pore volume pre- and post-drill.
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Evaluation of Norwegian Wildcat Wells (Article 1)
Norwegian Petroleum Society Special Publications, 2007Co-Authors: Kari Ofstad, Lars Kullerud, Dag HelliksenAbstract:This paper describes the objectives, organisation, datatypes and some selective results from the project: Evaluation of Norwegian Wildcat Wells. The project was initiated by the Norwegian Petroleum Directorate in 1996. Twenty oil companies participating in exploration on the Norwegian Continental Shelf have taken part in the project. The evaluation is a comparative of well prognoses versus results in order to use the past experience in future exploration. The project comprises 195 Wildcat Wells, including all those drilled on the Norwegian Continental Shelf between 1990 and 1997. Ten of the Wells were drilled in the Barents Sea, 40 in the Norwegian Sea and 145 Wells in the Norwegian part of the North Sea. The data types — a total of 114 parameters — are considered to be critical factors for future exploration success. For each well one or several prospects — and one or several cases — have been reported. This means that one well may have several prognoses, but only one result. The different companies' assessments of their dry Wells were also reported. The results show that hydrocarbon pore volume (HCPV) in 60% of the technical discoveries proved to be lower than the minimum probability estimate prior to drilling. The risked volume for all oil prospects is 2.5 times greater than the discovered volumes for oil discoveries. A similar comparison for all gas prospects and discoveries shows that the difference in the gas case is minor. The average discovery probability was 23% compared to the average technical finding rate that is 36%. The average discovery rate, excluding technical discoveries was 27%. In order to monitor future developments and improvements the project will be continued, incorporating new analyses in the future.
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probability of discovery and the reasons for dry Wells results from the project evaluation of norwegian Wildcat Wells article 3
Norwegian Petroleum Society Special Publications, 2000Co-Authors: Kari Ofstad, Lars Kullerud, Audun Ovretveit, Knut HegglandAbstract:The reasons for dry prospects reported by the oil companies in the project ‘Evaluation of Norwegian Wildcat Wells’ are compared with the probabilities for trap, charge and reservoir predicted prior to drilling. A comparison of the pre-drill probability assessment and results for the different probability factors has been performed, in addition to analysing the discovery probability by year, regions, plays, trap types, 2D and 3D seismic, in-place hydrocarbon volumes and the distance to nearest well. The results from the study show that lack of lateral seal, reservoir and migration were reported as the main reasons for dry prospects. On average the predicted discovery probability was slightly pessimistic, 23%, but fairly close to the actual discovery rate when the small technical discoveries are excluded, which is 27%. The results show that the petroleum explorationists were too pessimistic in evaluating trap probability and, to a lesser extent, charge and reservoir probabilities. Variation in discovery rate by year, regions and plays is only to some extent reflected in the pre-drill evaluation of the discovery probability. The results show that the discovery rate is highest in mature exploration areas within established plays. There is an apparently slightly higher discovery rate for prospects drilled on 3D seismic compared to 2D in the years 1990 to 1997. The results show that there is a strong inverse correlation between the discovery rate and the distance to the nearest well and a significant inverse correlation between the discovery rate and the predicted volumes of the prospects, but this is not clearly reflected when discovery probability is estimated.
Lars Kullerud - One of the best experts on this subject based on the ideXlab platform.
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Volumes before and after exploration drilling: results from the project: Evaluation of Norwegian Wildcat Wells (Article 2)
Norwegian Petroleum Society Special Publications, 2007Co-Authors: Lars Fosvold, Mark Thomsen, Mike L. Brown, Lars Kullerud, Kari Ofstad, Knut HegglandAbstract:In this study historical post-drill hydrocarbon pore volumes and input volumetric parameters have been compared with the most likely pre-drill prospect volumes and parameters in order to investigate how well the industry has predicted discovery sizes. The study shows that the hydrocarbon industry operating on the Norwegian Continental Shelf has more or less consistently overestimated hydrocarbon volumes. There are, however, indications that the industry's predictions on average are somewhat better in regions of longer exploration and drilling history. Still, one cannot demonstrate clear differences between highly explored versus less explored areas in the ability to make better volumetric predictions for a particular prospect. The variability in bulk rock volume prediction errors is clearly the most important factor when explaining the differences in hydrocarbon pore volume pre- and post-drill.
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Evaluation of Norwegian Wildcat Wells (Article 1)
Norwegian Petroleum Society Special Publications, 2007Co-Authors: Kari Ofstad, Lars Kullerud, Dag HelliksenAbstract:This paper describes the objectives, organisation, datatypes and some selective results from the project: Evaluation of Norwegian Wildcat Wells. The project was initiated by the Norwegian Petroleum Directorate in 1996. Twenty oil companies participating in exploration on the Norwegian Continental Shelf have taken part in the project. The evaluation is a comparative of well prognoses versus results in order to use the past experience in future exploration. The project comprises 195 Wildcat Wells, including all those drilled on the Norwegian Continental Shelf between 1990 and 1997. Ten of the Wells were drilled in the Barents Sea, 40 in the Norwegian Sea and 145 Wells in the Norwegian part of the North Sea. The data types — a total of 114 parameters — are considered to be critical factors for future exploration success. For each well one or several prospects — and one or several cases — have been reported. This means that one well may have several prognoses, but only one result. The different companies' assessments of their dry Wells were also reported. The results show that hydrocarbon pore volume (HCPV) in 60% of the technical discoveries proved to be lower than the minimum probability estimate prior to drilling. The risked volume for all oil prospects is 2.5 times greater than the discovered volumes for oil discoveries. A similar comparison for all gas prospects and discoveries shows that the difference in the gas case is minor. The average discovery probability was 23% compared to the average technical finding rate that is 36%. The average discovery rate, excluding technical discoveries was 27%. In order to monitor future developments and improvements the project will be continued, incorporating new analyses in the future.
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probability of discovery and the reasons for dry Wells results from the project evaluation of norwegian Wildcat Wells article 3
Norwegian Petroleum Society Special Publications, 2000Co-Authors: Kari Ofstad, Lars Kullerud, Audun Ovretveit, Knut HegglandAbstract:The reasons for dry prospects reported by the oil companies in the project ‘Evaluation of Norwegian Wildcat Wells’ are compared with the probabilities for trap, charge and reservoir predicted prior to drilling. A comparison of the pre-drill probability assessment and results for the different probability factors has been performed, in addition to analysing the discovery probability by year, regions, plays, trap types, 2D and 3D seismic, in-place hydrocarbon volumes and the distance to nearest well. The results from the study show that lack of lateral seal, reservoir and migration were reported as the main reasons for dry prospects. On average the predicted discovery probability was slightly pessimistic, 23%, but fairly close to the actual discovery rate when the small technical discoveries are excluded, which is 27%. The results show that the petroleum explorationists were too pessimistic in evaluating trap probability and, to a lesser extent, charge and reservoir probabilities. Variation in discovery rate by year, regions and plays is only to some extent reflected in the pre-drill evaluation of the discovery probability. The results show that the discovery rate is highest in mature exploration areas within established plays. There is an apparently slightly higher discovery rate for prospects drilled on 3D seismic compared to 2D in the years 1990 to 1997. The results show that there is a strong inverse correlation between the discovery rate and the distance to the nearest well and a significant inverse correlation between the discovery rate and the predicted volumes of the prospects, but this is not clearly reflected when discovery probability is estimated.
John H Schuenemeyer - One of the best experts on this subject based on the ideXlab platform.
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the evolution and use of discovery process models at the u s geological survey
AAPG Bulletin, 1993Co-Authors: Lawrence J Drew, John H SchuenemeyerAbstract:The development and the application of discovery process models have evolved to the point that these models now can be used to estimate the number of oil and gas fields remaining to be discovered in partially explored regions, and the rates at which fields will be discovered in the future. The fundamental data used to calibrate these models are taken from the systematic order that exists in the historical pattern of discovery in such regions (exploration plays, basins, provinces). The characteristic patterns of discovery vary from region to region, and ordinarily exhibit diminishing rates of return to Wildcat drilling as a function of field size. The number of fields remaining to be discovered in each field-size class is estimated by a two stage procedure: direct nonlinea estimation of fields in the portion of the size distribution not truncated by economic factors (larger fields) and indirect estimating by using a relative frequency factor for the field-size classes in the economically truncated portion of the distribution (smaller fields). The forecast of the future rates of discovery then considers the total range of field sizes, on the basis of Wildcat Wells drilled, by applying the discovery process model to both segments of the estimated size distribution. The application of this procedure is illustrated for a variety of onshore and offshore exploration plays from different geologic environments that have different economic conditions (size truncation points).
Dag Helliksen - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Norwegian Wildcat Wells (Article 1)
Norwegian Petroleum Society Special Publications, 2007Co-Authors: Kari Ofstad, Lars Kullerud, Dag HelliksenAbstract:This paper describes the objectives, organisation, datatypes and some selective results from the project: Evaluation of Norwegian Wildcat Wells. The project was initiated by the Norwegian Petroleum Directorate in 1996. Twenty oil companies participating in exploration on the Norwegian Continental Shelf have taken part in the project. The evaluation is a comparative of well prognoses versus results in order to use the past experience in future exploration. The project comprises 195 Wildcat Wells, including all those drilled on the Norwegian Continental Shelf between 1990 and 1997. Ten of the Wells were drilled in the Barents Sea, 40 in the Norwegian Sea and 145 Wells in the Norwegian part of the North Sea. The data types — a total of 114 parameters — are considered to be critical factors for future exploration success. For each well one or several prospects — and one or several cases — have been reported. This means that one well may have several prognoses, but only one result. The different companies' assessments of their dry Wells were also reported. The results show that hydrocarbon pore volume (HCPV) in 60% of the technical discoveries proved to be lower than the minimum probability estimate prior to drilling. The risked volume for all oil prospects is 2.5 times greater than the discovered volumes for oil discoveries. A similar comparison for all gas prospects and discoveries shows that the difference in the gas case is minor. The average discovery probability was 23% compared to the average technical finding rate that is 36%. The average discovery rate, excluding technical discoveries was 27%. In order to monitor future developments and improvements the project will be continued, incorporating new analyses in the future.