الفهرس 
Geological SettingOnly 14 pages are availabe for public view
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Abstract
WD33 Field, is located in the Eastern Abu El Gharadig development lease,comprissed within the northern Western Desert of Egypt. It lies between latitudes 29º 36` and 29º 48 ̀N, and longitudes 29º 00` and 29º 12` E,to the east of the Qattara Depression. The study area has been discovered and produced only from the Abu Roash-C Member. The presence of oil shows in WD33-15-1x well,as supported by the core data. In addition, we have oil shows in both WD33- 15-2 and WD33-15-7x wells. WD33-15-8x well was drilled targeting the Apollonia Formation, it came with good oil shows,as evidenced by the core data and preliminary log analysis, but unfortunately the test showed no hydrocarbon production and it produced only water ,with very few gases. The aim of this study is to integrate the seismic and petrophysical data, in order to get a relationship ,that could help to understand the carbonate rock behavior(represented by the Apollonia Formation) in the seismic data and to highlight the well locations, which expected to characterize good porosity and hydrocarbon saturation, that can be considered as a reservoir. The challenge in this study is the nature of Apollonia Formation carbonate rocks and its shallow depth in the study area. Also the type of hydrocarbon, which expected to be a heavy oil ,as shown from the results of the previous wells. This work has been done through a workflow, includes both qualitative and quantitative seismic interpretation. Also, constructing a three-dimentional structural and petrophysical model to understand the subsurface geology. The available data are 20 two-dimentional seismic reflection lines cover the area of interest, that are a part of a post-stack time migrated processed 3D seismic cube, had been selected to perform the structural seismic interpretation.also, four wells contain (the electric logs ,core data, mud logs and available core data. In addition, one check shot recorded data of WD33-15-8X well were used to perform the seismic to well tie and to estimate the required velocity. Seismic interpretation shows that , the structure of the evaluated area seems to be a four-way dip closure, with a minor normal fault trends (NW-SE) direction.After that, a three-dimentional model in time domain was constructed.Velocity model was performed to convert the model from time domain into depth domain, by using the time maps , formation tops and time depth relationship from wells. Seismic surface attributes were performed and show persuasive results. There are anomalies, which expected to have high porosity values especially around the crest of the structure of the Apollonia Formation and also towards the eastern part of the area of study. By the way, the effective porosity value in WD33-15-1x well is around 25% which considered to be high value and matched with thee anomaly in attributes results. Moreover, in WD33-15-2x well there is another anomaly and matched with effective porosity for this well which exceeds 30% percentage. The lower values in applied attributes towards north of this well might represent increasing in porosity due to the effect of the normal fault. The AVO modeling and fluid substitution modeling, show the possibility of hydrocarbon occurrence in the evaluated area, which are represented by decreasing in the negative amplitude. These results are good indication, to test this area by drilling new wells. The quantitative seismic Interpretation demonstrates how rock physics can be applied, to predict reservoir parameters, such as lithology and pore fluids. In this study, the seismic inversion was applied to estimate the absolute acoustic impedance by using simultaneous, stochastic and genetic seismic inversion. The wedge Model was performed first to know the maximum thickness of reservoir we can get. A thickness of 90’ feet was estimated to be the minimum thickness, which can be obtained from the seismic inversion. The simultaneous seismic inversion has the same resolution of the seismic survey, while the stochastic inversion has the resolution of the three-dimensional model, based on the number of layers. The genetic seismic inversion uses a neural network between the conventional seismic data and acoustic impedance logs from wells. The result from all type of seismic inversion show a decreasing in the acoustic impedance eat the crest of the structure, which matches with the seismic attribute results.
Also, extended elastic impedance was performed for fluid and lithology prediction. The cross plot of the extended elastic impedance versus Vp/Vs for WD33-15-1x well, by applying a rotation angle (chi angle) of 45 degree, show the possibility to discriminate between the shales of Dabaa Formation and the carbonates of Apollonia Formation. The Petrophysical Analysis shows estimated hydrocarbon pays in most of wells, up to 39’ feet in WD33-15-1X well. Also, the estimated effective porosity is good for all wells. It reaches about 31% in WD33-15-2x well. The cutoff for the porosity was selected, based on the porosity/permeability cross plot derived from core data for WD33-15-1x well. The thickness of the Apollonia reservoir is almost constant across all wells. Only WD33-15-1x well, shows pure limestone lithology at the top most part of the Apollonia Formation reservoir. The Petrophysical Modeling process was performed to distribute the petrophysical properties, by using of the available well data into a three-dimensional model. By the way, three types of properties were estimated. Net/gross, effective porosity and water saturation property. The results show enhancement towards the crest of the structure, especially around WD-33-15 well. It is important to integrate between the geophysical data (qualitative seismic interpretation, the non-conventional seismic interpretation) and geological data (well logs, mud logs, petrophysical analysis, three-dimensional property model and core data), in order to have a reasonable vision for the subsurface geology, and to add future plan for possible prospects in the study area. The core data for WD-33-15-1x shows oil-staining indication, also the mud log has a good indication of oil shows in most of wells. The low acoustic impedance anomaly close to WD33-15-1x well towards the northern direction, that could be an indication of the change of rock properties, including porosity and permeability. All of these data support each other that around WD33-15-1x well and towards the north direction of the crest of the structure is a promising area. The cross plot between the effective porosity and the absolute acoustic impedance from WD33-15-1x well, shows a reverse relationship between the two properties from well data. The effective porosity decreases, as a result of the acoustic impedance increasing. This relationship was used to re-distribute the effective porosity property, using the acoustic impedance from seismic inversion with co-kriging algorithm through the petrophysical modeling process. Petrel software uses Bayesian statistics to correlate the lithological interpretation of the wells with the acoustic impedance, to get a relationship, which used to convert the seismic data into lithofacies data set. The integration between the previous work and reference data from the surrounding fields, were resulted in a visualization of the petroleum system in the evaluated area. It suggests that, the Apollonia Formation reservoir accumulation at this depth of the reservoir, are known to have biodegraded oil. Regarding the migration, the oil generation started after both the Syrian Arc system tectonic events and deposition of the Apollonia Formation, where the kerogen is of type II and type-II/III organic content from marine input source. The structure seems to be a faulted anticlinal trap with fault trending (North West-South East) and the overlying Dabaa Formation shale facies suggests to be the top seal of our structure. For the reservoir characterization, the Apollonia facies is expected to be a good quality reservoir as logs and seismic inversion shows very good porosity exceeds 30%. Volumetric Calculation has been performed to estimate the expected oil accumulation.it shows around 39 millions stock oil in place.