Simultaneous waveform inversion was used to predict lithofacies and fluid type across the field. Very often, characterizing reservoirs in terms of lithology and fluid type using conventional methods is replete with un...Simultaneous waveform inversion was used to predict lithofacies and fluid type across the field. Very often, characterizing reservoirs in terms of lithology and fluid type using conventional methods is replete with uncertainties, especially in marginal fields. An approach is employed in this study that integrated rock physics and waveform inverse modelling for lithology and fluid-type characterization to appropriately identify potential hydrocarbon saturated zones and their corresponding lithology. Seismic and well-log data were analyzed using Hampson Russel software. The method adopted includes lithofacies and fluid content analysis using rock physics parameters and seismic simultaneous inverse modelling. Rock physics analysis identified 2 broad reservoirs namely: HDZ1 and HDZ2 reservoirs. Results from the inverse modelling showed that low values of acoustic impedance from 19,743 to 20,487 (ft/s)(g/cc) reflect hydrocarbon-bearing reservoirs while medium to high values shows brine and shale respectively, with brine zone ranging from 20,487 to 22,531 (ft/s)(g/cc) and shale above 22,531 (ft/s)(g/cc). Two lithofacies were identified from inversion analysis of Vp/Vs and Mu-Rho, namely: sand and shale with VpVs 1.95 values respectively. Mu-Rho > 12.29 (GPa)(g/cc) and <12.29 (GPa) (g/cc) represent sand and shale respectively. From 3D volume, it was observed that a high accumulation of hydrocarbon was observed to be saturated at the north to the eastern part of the field forming a meandering channel. Sands were mainly distributed around the northeastern to the southwestern part of the field, that tends to be away from Well 029. This was also validated by the volume of rigidity modulus (Mu-Rho) showing high values indicating sands fall within the northeastern part of the field.展开更多
The estimation of seismic reservoir properties faces difficulties such as delineating deceptive fluid contacts,over-estimating reserves and drilling dry holes.To overcome these problems,sequence strat-igraphic and roc...The estimation of seismic reservoir properties faces difficulties such as delineating deceptive fluid contacts,over-estimating reserves and drilling dry holes.To overcome these problems,sequence strat-igraphic and rock physics analyses that were constrained by the compaction trend were implemented in the Sigma Field.Sigma field is located in the Coastal Swamp depobelt,in the distal part.Seismic data from the field and a total of three wells,Sigma-30,26,and 25 were provided for the analyses.Biostratigraphic data was also given for the field and dated to shale marker Cassidulina-7.The strati-graphic sequence analysis of the wells in field indicate they were deposited in a regressive,transgressive and aggradational episodes,whereas the entire depositional history shows predominantly regressive episode.Three field reservoirs,SM-14(LST),SM-04(TST),and SM-02(HST)were delineated.Depositional analysis of the landscape from sequence stratigraphic analyses of the field indicates that Sigma feld reservoirs were deposited in a front region of the delta.Trend to compaction has been generated for the well.Sigma wells showed a normal trend toward compaction.Rock physics analysis of the reservoirs of interest reveals that LST and TST reservoirs have been dificult to distinguish against HST reservoirs which are easy to classify regardless of their depth for fluids in a Vp/Vs crossplot versus acoustic impedance.In the analysis,a pattern is suggested for TST reservoirs.Therefore,this research work shows that fluid discrimination becomes simpler as we go basin ward as the sorting of the reservoir rocks increases with finer grain sand sizes.展开更多
文摘Simultaneous waveform inversion was used to predict lithofacies and fluid type across the field. Very often, characterizing reservoirs in terms of lithology and fluid type using conventional methods is replete with uncertainties, especially in marginal fields. An approach is employed in this study that integrated rock physics and waveform inverse modelling for lithology and fluid-type characterization to appropriately identify potential hydrocarbon saturated zones and their corresponding lithology. Seismic and well-log data were analyzed using Hampson Russel software. The method adopted includes lithofacies and fluid content analysis using rock physics parameters and seismic simultaneous inverse modelling. Rock physics analysis identified 2 broad reservoirs namely: HDZ1 and HDZ2 reservoirs. Results from the inverse modelling showed that low values of acoustic impedance from 19,743 to 20,487 (ft/s)(g/cc) reflect hydrocarbon-bearing reservoirs while medium to high values shows brine and shale respectively, with brine zone ranging from 20,487 to 22,531 (ft/s)(g/cc) and shale above 22,531 (ft/s)(g/cc). Two lithofacies were identified from inversion analysis of Vp/Vs and Mu-Rho, namely: sand and shale with VpVs 1.95 values respectively. Mu-Rho > 12.29 (GPa)(g/cc) and <12.29 (GPa) (g/cc) represent sand and shale respectively. From 3D volume, it was observed that a high accumulation of hydrocarbon was observed to be saturated at the north to the eastern part of the field forming a meandering channel. Sands were mainly distributed around the northeastern to the southwestern part of the field, that tends to be away from Well 029. This was also validated by the volume of rigidity modulus (Mu-Rho) showing high values indicating sands fall within the northeastern part of the field.
文摘The estimation of seismic reservoir properties faces difficulties such as delineating deceptive fluid contacts,over-estimating reserves and drilling dry holes.To overcome these problems,sequence strat-igraphic and rock physics analyses that were constrained by the compaction trend were implemented in the Sigma Field.Sigma field is located in the Coastal Swamp depobelt,in the distal part.Seismic data from the field and a total of three wells,Sigma-30,26,and 25 were provided for the analyses.Biostratigraphic data was also given for the field and dated to shale marker Cassidulina-7.The strati-graphic sequence analysis of the wells in field indicate they were deposited in a regressive,transgressive and aggradational episodes,whereas the entire depositional history shows predominantly regressive episode.Three field reservoirs,SM-14(LST),SM-04(TST),and SM-02(HST)were delineated.Depositional analysis of the landscape from sequence stratigraphic analyses of the field indicates that Sigma feld reservoirs were deposited in a front region of the delta.Trend to compaction has been generated for the well.Sigma wells showed a normal trend toward compaction.Rock physics analysis of the reservoirs of interest reveals that LST and TST reservoirs have been dificult to distinguish against HST reservoirs which are easy to classify regardless of their depth for fluids in a Vp/Vs crossplot versus acoustic impedance.In the analysis,a pattern is suggested for TST reservoirs.Therefore,this research work shows that fluid discrimination becomes simpler as we go basin ward as the sorting of the reservoir rocks increases with finer grain sand sizes.
