The study involved the evaluation of the hydrocarbon potential of FORMAT Field, coastal swamp depobelt Niger delta, Nigeria to obtain a more efficient reservoir characterization and fluid properties identification. De...The study involved the evaluation of the hydrocarbon potential of FORMAT Field, coastal swamp depobelt Niger delta, Nigeria to obtain a more efficient reservoir characterization and fluid properties identification. Despite advances in seismic data interpretation using traditional 3D seismic data interpretation, obtaining adequate reservoir characteristics at the finest level had proved very challenging with often disappointing results. A method that integrates the amplitude variation with offfset (AVO) analysis is hereby proposed to better illuminate the reservoir. The Hampson Russell 10.3 was used to integrate and study the available seismic and well data. The reservoir of interest was delineated using the available suite of petrophysical data. This was marked by low gamma ray, high resistivity, and low acoustic impedance between a true subsea vertical depth (TVDss) range of 10,350 - 10,450 ft. The AVO fluid substitution yielded a decrease in the density values of pure gas (2.3 - 1.6 g/cc), pure oil (2.3 - 1.8 g/cc) while the Poisson pure brine increased (2.3 to 2.8 g/cc). Result from FORMAT 26 plots yielded a negative intercept and negative gradient at the top and a positive intercept and positive gradient at the Base which conforms to Class III AVO anomaly. FORMAT 30 plots yielded a negative intercept and positive gradient at the top and a positive intercept and negative gradient at the Base which conforms to class IV AVO anomaly. AVO attribute volume slices decreased in the Poisson ratio (0.96 to - 1.0) indicating that the reservoir contains hydrocarbon. The s-wave reflectivity and the product of the intercept and gradient further clarified that there was a Class 3 gas sand in the reservoir and the possibility of a Class 4 gas sand anomaly in that same reservoir.展开更多
In the last decade, the seismic AVO analysis have become prominent in the direct hydrocarbons indicator(DHI), aimed at characterizing the fluid content or the lithology of a possible reservoir and reducing theexplorat...In the last decade, the seismic AVO analysis have become prominent in the direct hydrocarbons indicator(DHI), aimed at characterizing the fluid content or the lithology of a possible reservoir and reducing theexploration drilling risk. This research discuss the impact of studying the common depth point (CDP)gathers on Near, Mid and Far-offsets, to verify the credibility of the amplitude response in the prospectevaluation, through analyzing a case study of two exploratory wells;one has already penetrated a gasbearing sandstone as a reservoir and the other one is dry-sand, but drilled in two different prospects,using the amplitude versus offset (AVO) analysis, to understand the reservoir configuration and itsrelation to the different amplitude response. The results show, that the missing of the short-offset data isthe reason of the false anomaly encountered in the dry sand, due to some urban surface obstacles duringacquiring the seismic data in the field especially, the study area is located in El Mansoura city, which it isa highly cultivated flat terrain, with multiple channels and many large orchards on the edge of the river,and sugar cane and rice fields. Several lessons have been learned, which how to differentiate between thegas reservoirs and non-reservoirs, by understanding the relation between the Near and Far-offset traces,to reduce the amplitude anomalies to their right justification, where missing of Near-offset data led to apseudo-amplitude anomaly. The results led to a high success of exploration ratio as the positives vastlyoutweigh the negatives.展开更多
文摘The study involved the evaluation of the hydrocarbon potential of FORMAT Field, coastal swamp depobelt Niger delta, Nigeria to obtain a more efficient reservoir characterization and fluid properties identification. Despite advances in seismic data interpretation using traditional 3D seismic data interpretation, obtaining adequate reservoir characteristics at the finest level had proved very challenging with often disappointing results. A method that integrates the amplitude variation with offfset (AVO) analysis is hereby proposed to better illuminate the reservoir. The Hampson Russell 10.3 was used to integrate and study the available seismic and well data. The reservoir of interest was delineated using the available suite of petrophysical data. This was marked by low gamma ray, high resistivity, and low acoustic impedance between a true subsea vertical depth (TVDss) range of 10,350 - 10,450 ft. The AVO fluid substitution yielded a decrease in the density values of pure gas (2.3 - 1.6 g/cc), pure oil (2.3 - 1.8 g/cc) while the Poisson pure brine increased (2.3 to 2.8 g/cc). Result from FORMAT 26 plots yielded a negative intercept and negative gradient at the top and a positive intercept and positive gradient at the Base which conforms to Class III AVO anomaly. FORMAT 30 plots yielded a negative intercept and positive gradient at the top and a positive intercept and negative gradient at the Base which conforms to class IV AVO anomaly. AVO attribute volume slices decreased in the Poisson ratio (0.96 to - 1.0) indicating that the reservoir contains hydrocarbon. The s-wave reflectivity and the product of the intercept and gradient further clarified that there was a Class 3 gas sand in the reservoir and the possibility of a Class 4 gas sand anomaly in that same reservoir.
基金The authors would like to extend their sincere appreciation and great thanks to the Egyptian Natural Gas Holding Company(EGAS),Petroceltic-International Plc and El Mansoura Petroleum Company for all their support during the production of this work.
文摘In the last decade, the seismic AVO analysis have become prominent in the direct hydrocarbons indicator(DHI), aimed at characterizing the fluid content or the lithology of a possible reservoir and reducing theexploration drilling risk. This research discuss the impact of studying the common depth point (CDP)gathers on Near, Mid and Far-offsets, to verify the credibility of the amplitude response in the prospectevaluation, through analyzing a case study of two exploratory wells;one has already penetrated a gasbearing sandstone as a reservoir and the other one is dry-sand, but drilled in two different prospects,using the amplitude versus offset (AVO) analysis, to understand the reservoir configuration and itsrelation to the different amplitude response. The results show, that the missing of the short-offset data isthe reason of the false anomaly encountered in the dry sand, due to some urban surface obstacles duringacquiring the seismic data in the field especially, the study area is located in El Mansoura city, which it isa highly cultivated flat terrain, with multiple channels and many large orchards on the edge of the river,and sugar cane and rice fields. Several lessons have been learned, which how to differentiate between thegas reservoirs and non-reservoirs, by understanding the relation between the Near and Far-offset traces,to reduce the amplitude anomalies to their right justification, where missing of Near-offset data led to apseudo-amplitude anomaly. The results led to a high success of exploration ratio as the positives vastlyoutweigh the negatives.
