Western Desert represents a major oil and gas province in Egypt producing more than 50%of the country’s oil production.Oil and gas blend occurs in most producing fields,however,the genetic link between gas and liquid...Western Desert represents a major oil and gas province in Egypt producing more than 50%of the country’s oil production.Oil and gas blend occurs in most producing fields,however,the genetic link between gas and liquid hydrocarbon phases are not well-constrained.Obayied sub-basin in the Western Desert where oil and gas phases coexist in the Middle Jurassic sandstones of the Khatatba Formation provides an ideal place to investigate the link between oil and gas generation.Geochemical analyses on rock samples(Rock–Eval pyrolysis,vitrinite reflectance,R_(o))and gases(molecular and isotopic composition)were conducted in order to identify the genetic characteristics of the hydrocarbon phases produced.Maturity-relevant parameters(Rock–Eval T_(max),vitrinite reflectance R_(o))elucidate that only Middle Jurassic Khatatba organofacies capable of generating wet and dry hydrocarbon gases.Additionally,the enrichment of C_(7)normal alkanes,mono-branched alkanes relative to polybranched components in the Obayied gases reflect their generation via cracking of oil.Basin modelling results confirm gas generation through both primary and secondary cracking.However,secondary cracking of liquid hydrocarbon phases is volumetrically more significant.Primary cracking of the Khatatba organofacies likely predate and catalyze the secondary cracking of the liquid phases and therefore the volume of generated gas increases incrementally eastward where both processes coexist.The present study highlights the significant role of secondary cracking in the generation and accumulation of huge gas accumulations in the basins containing oil-prone source intervals.展开更多
The Messinian sequence in the Nile Delta hosts the most prolific hydrocarbon reservoirs,and is therefore of great importance from the aspect of nonrenewable fuel sources exploration and development strategies.This stu...The Messinian sequence in the Nile Delta hosts the most prolific hydrocarbon reservoirs,and is therefore of great importance from the aspect of nonrenewable fuel sources exploration and development strategies.This study presents an investigation for the differential impacts of the depositional and petrophysical attributes on the hydrocarbon volumes trapped in the Messinian reservoirs.Analyses of the pressure data and pressure gradients revealed hydraulically-connected and homogeneous Messinian reservoir rocks.The amounts of Stock Tank Oil and Gas Initially In Places(STOIPP&GIIP)are typically controlled by the depositional primary attributes(matrix content and grain size)which induce several reservoir heterogeneities.The Lower Messinian Qawasim reservoir is subdivided into two main zones:the distal deltaic(zone 1)prograded into proximal deltaic facies(zone 2).The petrophysical reservoir quality in terms of porosity,permeability and water saturation increases upward from zone 1 to zone 2.These are largely controlled by the depositional attributes,and therefore zone 2 with a minimum matrix content,coarse-grained sandstones and mega pore spaces(>150 mm)hosts almost 90%of the STOIIP and 100%of the GIIP.Notably,approximately 78%and 65%of the total STOIIP and GIIP,respectively are confined within the coarse-grained delta-plain distributary channels of zone 2.Similarly,the fluvial sediments(zone 1)of the Upper Messinian Abu Madi Formation host 78%of the GIIP in West Al-Khilala Field and the other 22%is trapped in the overlying zone 2 and is mostly distributed within the sandprone tidal channel and tidal sand bars facies.The channel width/thickness(W/T)ratio largely controls the STOIIP and GIIP values.STOIIP and GIIP display a progressive linear increase with increasing the channel width.This is likely due to increasing the percentage of the good reservoir quality facies within the geologic model as well as increasing the reservoir connectivity with increasing the channel width.展开更多
文摘Western Desert represents a major oil and gas province in Egypt producing more than 50%of the country’s oil production.Oil and gas blend occurs in most producing fields,however,the genetic link between gas and liquid hydrocarbon phases are not well-constrained.Obayied sub-basin in the Western Desert where oil and gas phases coexist in the Middle Jurassic sandstones of the Khatatba Formation provides an ideal place to investigate the link between oil and gas generation.Geochemical analyses on rock samples(Rock–Eval pyrolysis,vitrinite reflectance,R_(o))and gases(molecular and isotopic composition)were conducted in order to identify the genetic characteristics of the hydrocarbon phases produced.Maturity-relevant parameters(Rock–Eval T_(max),vitrinite reflectance R_(o))elucidate that only Middle Jurassic Khatatba organofacies capable of generating wet and dry hydrocarbon gases.Additionally,the enrichment of C_(7)normal alkanes,mono-branched alkanes relative to polybranched components in the Obayied gases reflect their generation via cracking of oil.Basin modelling results confirm gas generation through both primary and secondary cracking.However,secondary cracking of liquid hydrocarbon phases is volumetrically more significant.Primary cracking of the Khatatba organofacies likely predate and catalyze the secondary cracking of the liquid phases and therefore the volume of generated gas increases incrementally eastward where both processes coexist.The present study highlights the significant role of secondary cracking in the generation and accumulation of huge gas accumulations in the basins containing oil-prone source intervals.
基金Egyptian Ministry of Higher Education and Scientific Research(Grant number 2014-2018)for funding this study.
文摘The Messinian sequence in the Nile Delta hosts the most prolific hydrocarbon reservoirs,and is therefore of great importance from the aspect of nonrenewable fuel sources exploration and development strategies.This study presents an investigation for the differential impacts of the depositional and petrophysical attributes on the hydrocarbon volumes trapped in the Messinian reservoirs.Analyses of the pressure data and pressure gradients revealed hydraulically-connected and homogeneous Messinian reservoir rocks.The amounts of Stock Tank Oil and Gas Initially In Places(STOIPP&GIIP)are typically controlled by the depositional primary attributes(matrix content and grain size)which induce several reservoir heterogeneities.The Lower Messinian Qawasim reservoir is subdivided into two main zones:the distal deltaic(zone 1)prograded into proximal deltaic facies(zone 2).The petrophysical reservoir quality in terms of porosity,permeability and water saturation increases upward from zone 1 to zone 2.These are largely controlled by the depositional attributes,and therefore zone 2 with a minimum matrix content,coarse-grained sandstones and mega pore spaces(>150 mm)hosts almost 90%of the STOIIP and 100%of the GIIP.Notably,approximately 78%and 65%of the total STOIIP and GIIP,respectively are confined within the coarse-grained delta-plain distributary channels of zone 2.Similarly,the fluvial sediments(zone 1)of the Upper Messinian Abu Madi Formation host 78%of the GIIP in West Al-Khilala Field and the other 22%is trapped in the overlying zone 2 and is mostly distributed within the sandprone tidal channel and tidal sand bars facies.The channel width/thickness(W/T)ratio largely controls the STOIIP and GIIP values.STOIIP and GIIP display a progressive linear increase with increasing the channel width.This is likely due to increasing the percentage of the good reservoir quality facies within the geologic model as well as increasing the reservoir connectivity with increasing the channel width.
