An Integrated Petrophysical, Geochemical and Operational Approach to Identify Unconventional Resource, Case Study, Obaiyed Field, Western Desert-Egypt.

Abstract

Histrorically, Upper Safa is considered to be the source rock of the gas and condensate accumulated in Lower Safa stratum in Obaiyed Field. Both of Upper and Lower Safa units are parts of Khatatba formation "Jurassic age, Western Desert coulumn, Egypt". The integration of all petrophysical and geochemical data indicated that, there is a rich organic Carbon embedded in the formation with a high britteleness ratio. As a result of the opportunity identification, there is an operational scope being studied now to proceed with a haydrulic fracturing stimulation targeting the sweet intervals "Intervals of high TOC and high Britteleness ratio" aiming to maximize the whole gas and condensate production of the field. This paper is summarizing the opportunity identification process and results using available petrophysical and geochemical data.Six wells had been used in this study where there is a complete set of well and continuous petrophysical data exist in all of them supported by geochemical analysis reports. Specific interpretation techniques were utilized to identify the opportunity from the logs. The property of Total Organic Carbon was estimated from logs using standered DeltaLogR Passey Technique and then verified using measured data. The rock briteleness property was estimated from avilable acoustic sonic logs "Compressional and Shear slowness". The type of Kerogen and level of Maturity were recognized from geochemical sources. The data integration provided a well identification of the shale gas opportunity.As a part of complete assessment study of unconventional resources, a dedicated subsurface team was formed in order to evaluate the connectivity of Upper Safa, estimate the in place volumes and define the development options. The team also proposed on short term scale performing a vertical hydraulic fracturing in one of the sweet wells in order to prove the evaluation concept and increase total field production.The success of this project is measured by three aspects: first, proving the presence of commercial shale gas plays in Upper Safa unit, second, maximizing the gas and condensate production from the field and finally, on the long term scale, unlocking commercial unconventional gas resource for future generations in Western Desert, Egypt.

Petro-Physical and Geo-Mechanical Analysis of the Unconventional Upper Safa Formation, Western Desert, Egypt

“…The analysis of the geochemical output data is indicting that Upper Safa formation which is a sub unit of Khatatba formation consists of shales and coals with kerogen type III. In addition, the pyrolysis analysis through relationship between oxygen index and hydrogen index, are also supporting the kerogen type III from the obtained and analyzed samples by Ghanima et al (2015). Therefore, Upper safa formation is a good candidate for having hydrocarbon gases as an unconventional shale gas reservoir with TOC value within the range of the potential of hydrocarbon gases which is more than 2% of TOC content.…”

“…Hydrogen index directly depends on the hydrocarbon density either gas or oil for all unconventional plays. According to this case study of having hydrocarbon density equals 0.17 g/cc of shale gas fluid, thus having hydrogen index value equals 0.3 for Upper Safa formation [8]. There is few logs data information obtained and given about Upper Safa formation.…”

“…Ghanima et al (2015) reported that identifying unconventional reservoir resources by integrated petrophysical, geochemical, and operational approaches [8]. The integrations of all petrophysical and geochemical data, are defining the total organic carbon and brittleness ratio of the formation.…”

“…(Fig:A) Pyrolysis analysis of Upper Safa formation (Ghanima et al, 2015),. where(Fig:B) indicate the real core analysis for this data[8] Level of Maturity LOM: The Vitrinite reflection (VR) is the main important factor used for determination of level of maturity, which is the percentage of incident light reflected from surface of particles of vitrinite in shale rocks. However, Upper safa formation is characterized by an average percentage value ofvitrinite reflection equal 1.5%.…”

New Approach for Unconventional Reservoirs Rock Typing Characterization: Egyptian Unconventional Gas Reservoirs

“…Thus, the main solution of this complex economical Egyptian situation is exploitation of tremendous unconventionally potential, including oil shale and tight gas sands that will be the major contributors of the Egyptian primary energy consuming in the energy market of Egypt. 1994), Reservoir characterization and properties have great influences on the exploration and development processes [8]. To understand more and more about reservoir properties, it is not through a single discipline that can provide a fulfill description of the reservoir characteristics.…”