Palynological study of an offshore well in the Niger delta was carried out to document the palynomorphs assemblage and subsequently date and establish paleoclimatic conditions in a portion of the Niger delta. One hund...Palynological study of an offshore well in the Niger delta was carried out to document the palynomorphs assemblage and subsequently date and establish paleoclimatic conditions in a portion of the Niger delta. One hundred and thirty seven cutting samples provided by Chevron Nigeria Plc were composited at 27 m interval for the study. The samples yielded forty six palynomorphs, which include Racemonocolpites hians, Zonocostites ramonae, Monoporites annulatus, Botryococcusbraunii, dinocyst Lycopodiumsporites spp., Pachydermitesdiederixi and Psilatricolporitescrassus. A Middle-Late Miocene age belonging to P800 and P700 zones of Germeraad was established for the interval studied. There were clear crests and troughs in the microfloral abundance indicative of alternations of dry and wet climatic conditions during the deposition of the Agbada Formation.展开更多
Core samples representing depths of hydrocarbon-bearing zones are not readily accessible for reservoir evaluations.On the other hand,wireline logs with incorporated seismic data,which can be archived over a more exten...Core samples representing depths of hydrocarbon-bearing zones are not readily accessible for reservoir evaluations.On the other hand,wireline logs with incorporated seismic data,which can be archived over a more extended period while retaining their original forms,are typically more available for research purposes.Therefore,the study relies on wireline logs with seismic data to predict the reservoirs'fluid mobility by evaluating the hydraulic(flow)units,reservoir depths,fluid saturations,and geothermal gradients.It also indicates the associated water cut(C_(w))within Ritchie oil and gas field,Niger Delta considering a three-phase(oil-gas-water-bearing)reservoir(R_(A))and an oil-saturated reservoir(R_(B))delineated across three wells(R_(W1),R_(W2) and R_(W3)).Research activities combining the presented factors to achieve the stated objectives are not quite common within the study location.It shows lower,average and upper limits of the flow unit factors and irreducible water saturation(S_(wirr))within the reservoirs.The study shows the relationship between hydraulic units/fluid saturations and fluid mobility/associated C_(w) within the sandstone reservoirs.It maximises porosity(Ф)for the theoretical flow units'prediction during qualitative and quantitative estimation based on the adopted expressions.Therefore,the study reveals that water saturation(S_(w))and hydrocarbon/water ratios substantially control C_(w),and other contributing factors include thermal gradients and S_(wirr).The flow unit factors are also significant and will encourage fluid mobility.The evaluated reservoirs(R_(A) and R_(B))are below 10400 ft(3170 m)across wells R_(W1),R_(W2) and R_(W3) within the Agbada Formation of a geothermal gradient up to 2.7℃/100 m;therefore,they have good thermal conditions to enhance hydrocarbon mobility and increase S wirr.Hence,the reservoir should feature significant hydrocarbon extraction via primary recovery.The average water cut(C_(w-avg).)(12.3%)estimated for reservoir R_(A) is within the acceptable range;therefore,the associated water production from the three-phase reservoir will not be much of a concern.In addition,simple models are presented to aid an alternative approach for predicting reservoir quality and C_(w) within sandstone res-ervoirs,especially in the absence of core samples.展开更多
文摘Palynological study of an offshore well in the Niger delta was carried out to document the palynomorphs assemblage and subsequently date and establish paleoclimatic conditions in a portion of the Niger delta. One hundred and thirty seven cutting samples provided by Chevron Nigeria Plc were composited at 27 m interval for the study. The samples yielded forty six palynomorphs, which include Racemonocolpites hians, Zonocostites ramonae, Monoporites annulatus, Botryococcusbraunii, dinocyst Lycopodiumsporites spp., Pachydermitesdiederixi and Psilatricolporitescrassus. A Middle-Late Miocene age belonging to P800 and P700 zones of Germeraad was established for the interval studied. There were clear crests and troughs in the microfloral abundance indicative of alternations of dry and wet climatic conditions during the deposition of the Agbada Formation.
文摘Core samples representing depths of hydrocarbon-bearing zones are not readily accessible for reservoir evaluations.On the other hand,wireline logs with incorporated seismic data,which can be archived over a more extended period while retaining their original forms,are typically more available for research purposes.Therefore,the study relies on wireline logs with seismic data to predict the reservoirs'fluid mobility by evaluating the hydraulic(flow)units,reservoir depths,fluid saturations,and geothermal gradients.It also indicates the associated water cut(C_(w))within Ritchie oil and gas field,Niger Delta considering a three-phase(oil-gas-water-bearing)reservoir(R_(A))and an oil-saturated reservoir(R_(B))delineated across three wells(R_(W1),R_(W2) and R_(W3)).Research activities combining the presented factors to achieve the stated objectives are not quite common within the study location.It shows lower,average and upper limits of the flow unit factors and irreducible water saturation(S_(wirr))within the reservoirs.The study shows the relationship between hydraulic units/fluid saturations and fluid mobility/associated C_(w) within the sandstone reservoirs.It maximises porosity(Ф)for the theoretical flow units'prediction during qualitative and quantitative estimation based on the adopted expressions.Therefore,the study reveals that water saturation(S_(w))and hydrocarbon/water ratios substantially control C_(w),and other contributing factors include thermal gradients and S_(wirr).The flow unit factors are also significant and will encourage fluid mobility.The evaluated reservoirs(R_(A) and R_(B))are below 10400 ft(3170 m)across wells R_(W1),R_(W2) and R_(W3) within the Agbada Formation of a geothermal gradient up to 2.7℃/100 m;therefore,they have good thermal conditions to enhance hydrocarbon mobility and increase S wirr.Hence,the reservoir should feature significant hydrocarbon extraction via primary recovery.The average water cut(C_(w-avg).)(12.3%)estimated for reservoir R_(A) is within the acceptable range;therefore,the associated water production from the three-phase reservoir will not be much of a concern.In addition,simple models are presented to aid an alternative approach for predicting reservoir quality and C_(w) within sandstone res-ervoirs,especially in the absence of core samples.
