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Geology/Petrophysical analysis.

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Question
Sir,

We are using different logs for lithology identification like GR sonic, resistivity etc but during drilling we also have cuttings comes out from borehole through which mud log is created. my question is why we are expending a huge amount on these logging suits however we have mudlog from which we can directly identify lithology.

Answer
Kaleem,

The Electric Logs are not just for identification of lithology, that we surely get much better from the Mud Log because we see the cuttings directly. E.Logs are basically to identify/interpret the petrophysical characteristics (porosity, permeability etc) and the type of fluids (oil, gas, water) in a reservoir, and the hydrocarbon-aquifer contacts immediately after the drilling and before the casings are set.

We can get the petrophysical characteristics of the rocks by laboratory studies and quantify them much better than we interpret from E.Logs but those will be available much later as the cuttings and core samples have to be sent to laboratories. We at well site need the above information on a fast track to decide about casing shoe depth, perforations, number of reservoirs and the fluid contacts within, and the reservoir pressure etc. So that 'huge amount' is nothing compared to the Rig, Mud Unit, Cementation unit rentals and other related equipment, and the charges for the operating staff. Every hour on well-site incurs huge expenses, and faster the contracted crews are demobilized, the better the overall cost of the well would be.

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Nusrat Kamal Siddiqui (Mr)

Expertise

I am a petroleum exploration geologist with about 40+ years of diversified experience. I can answer questions on stratigraphy, log interpretation, field studies based on set of logs and core results, general geology etc. Can provide guidance for career planning in earth sciences. Can not help in questions about hard rocks, igneous petrology & mineralogy, sequence stratigraphy and seismic.

Experience

Petroleum Exploration - field geology, stratigraphy, prospect generation, interpretation of satellite imagery (visual), log interpretation.

Organizations
Retired in May, 2006 as Senior Manager Exploration from Pakistan Petroleum Limited after serving 26 years. Since then continuing in active service with petroleum exploration companies.A cumulative experience of about 40 years covers 30 years in petroleum exploration, 5 years hydrogeology experience in Libya, and about 5 years of dam geology in Pakistan.

Publications
-AAPG Bulletin (Vol.88, July, 2004); paper on Sui Main Limestone (Eocene), a prolific gas reservoir in Pakistan. -Have presented papers on diversified topics ranging from spirituality, flood control, remote sensing and off course geology in France, Nepal, Bangladesh, Sri Lanka, UAE, Kashmir, India and Pakistan that have been published in respective Special Proceedings. -ONGC Bulletin(India) Vol. 44, Number 2, December, 2009; Chapter 19.A & 19.B on basin architecture and stratigraphy of Pakistan, p.402-474.

Education/Credentials
BSc Honours in Geology and Master of Science in Petroleum and Structural Geology. PGD from ITC, The Netherlands.

Awards and Honors
-Remained Active Member of AAPG from 1990-2006; founding member of PAPG (a local affiliate of AAPG). -Life member of SEGMITE & AGID, and Senior Editor of SEGMITE magazine. -Member of the Board of Studies, i. Department of Petroleum & Gas Engineering (BUITMS, Quetta), and ii. Geology Department, Sindh University, Jamshoro. -Member of Stratigraphic Committee of Pakistan. -Represented Mining Journal, UK in Pakistan till 2007. -Chairman of Annual Technical Conference (ATC)& Oil Show, an SPE/PAPG annual event, in 2003. -Chairman Technical Committee (ATC, 2002).

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