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Geology/limestone with secondary porosity?


QUESTION: is there any limestone in Pakistan with primary porosity?

ANSWER: Muhammad,

Sui Main Limestone (Ypresian) is one, with primary porosity. It is dominantly a chalky  limestone wherein a very early charge of gas occurred, that preserved the primary porosity.

You may go through my paper  on SML published in AAPG Bulletin, July, 2004.

---------- FOLLOW-UP ----------

QUESTION: what are the ways to generate secondary porosity?


The two conventional ways are, as under:

For sandstone (clastics in general) we go for Hydraulic Fracturing. A designed liquid, which contains solid micro-globules is pushed into the reservoir rock that enters the fractures created due to the pressure. Once the pressure is released the micro-globules remain within the fractures and keep it open.

For limestone (carbonates in general) a process known as Acidization is carried out. The acid enters the microfractures and widens them to increase the porosity, and connects adjacent set of fractures to increase the permeability.  


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Nusrat Kamal Siddiqui (Mr)


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.


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

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.

-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.

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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