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haloo
     My question is the role of porosity in control oil and gas also and the importance of porosity in oil and gas.

Answer
Dear George Mrema,

My sincere apologies for delayed response to you. I thank you for sending me this question.

Here is my answer;

Porosity is the key component for oil and gas accumulation. Porosity is the ratio of the volume of interstices (pores or gaps) of a material to the volume of its mass. The pores are voids in between rocks grains.Take an example of rooms in a house so the rooms are porosity where people live while the oil and gas are being lived in porosity. More bigger the rooms more space for oil, water or gas storage. Porosity is expressed in percent of the rock mass.

In a mathematical expression; if  1 cubic meter rocks has 10 percent pores, means the pores storage  volumes would be 1/10 = 0.01 Cubic meter of oil or water.

There are two kind of natural Porosity in any rock 1)primary porosity which were developed at the time of the deposition of the rock 2) Secondary porosity which were developed after the deposition of the rock either due to mineralization (dolomitization or mineral replacement) or diagenesis (more than one mineral reaction with host rock) or by fracturing.

Bigger the porosity number more volume of oil and gas rock may store. The primary porosity in sandstone may vary from  as low as 5 percent to as high as 40 percent whereas limestone varies between 4 to 38 percent. In order to have a reservoir rock with excellent permeability pore structures should be connected with other pores which will allow oil and gas to flow freely. Some rocks have higher porosities such as shale and claystone but since their pores are not very well aligned and connected to each other the permeabilities are far too low than sandstones and limestones.

Keep in mind that during the life of any rock porosity has been reduced by cementation and compaction whereas diagenesis may enhance the porosity and peremability in certain cases.

Hope this answer helps you well.

Regards

Tariq

Geology

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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

Experience

Petroleum Exploration

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Petronas Carigali Sdn Bhd

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In Pakistani and Asian Petroleum Confertence special Publications

Education/Credentials
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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