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Geology/migration of oil

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Question
Hi Sir. My question is that how migration of oil is more efficient through faults? the faults can become active or it may destroyed the nearby reserviors at the time of its (fault) formation or its activeness.

Answer
Dear Wasim,

Thanks for sending me your question.

A fault is a zone of general weakness in rock surface where some kind of observable movement or displacement along two sides has taken place.Thrust or reverse faults tend to converge over the strata due to compressional forces and, therefore there is a possibility that neighborhood area distorted the reservoir. Tensional or gravity fault forms  a gap between two strata when faulting takes place, therefore, there is a possibility that reservoir has improved due to fracturing.

However, after faulting if sedimentation continues the fault gap either filled by new sediments or adjacent overlying rocks slide down and filled the fault gap. During faulting substantial grinding and rubbing of rock grains, due to the tectonic forces, takes place which alter the grains and geometry of the rock and form polished a crystalline surface   along the fault path which may be very impermeable resulting diminishing of the  reservoir  if not totally destroyed.

So, the faults may act both ways, may destroy the reservoir or may also enhance the quality, so we have to be careful in the fault analysis.

Therefore, we have to see few aspects of any fault; determine type of faulting, fault gap. gap filling material, lithology juxtaposed across the fault, the distance of the fault throw and the age of the fault.

Old fault tends to be healed up by later sediments filling processes while the new faults likely to be either open or partially filled.

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Syed Tariq Hasany

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MY HUMBLE REQUEST. BEFORE SENDING A QUESTION PLEASE READ THE FOLLOWING CAREFULY. ANSWERING ONLY PUBLIC QUESTIONS. Ask questions of exploration of Petroleum, and specific regions for specific answers about Pakistan, Central Asia, Middle East and Far East. Ask questions of Business side of the petroleum Geology. Love to guide students and also Career related issues PRIVATE QUESTIONS on thasany@yahoo.com I am not expert of Hard rocks (Igneous and metamorphic rocks)Volcanic activity and related petrology, mineralogy and its exploration. BE SPECIFOC WHAT YOU WANT TO KNOW AND ASK WITH DIGNITY AND RESPECT. Show me your determination and commitment to learn. PLEASE TRY TO WRITE RIGHT, PROPER AND CORRECT LANGUAGE. DO NOT USE TEXT(SMS)STYLE. Thanks TARIQ

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Petroleum Exploration

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Petronas Carigali Sdn Bhd

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In Pakistani and Asian Petroleum Confertence special Publications

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BSc Honours in Geology and Master of Science degree in Petroleum Geology

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Active member AAPG, SPE and PAPG Treasurer PAPG and AAPG Visiting Geoscientist

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