Importantance of minor occurrence or showings
اهميه الاحداث السطحيه والاحداث التحت سطحيه
Although not important for economical development minor occurrences are consider important because
They indicate that some of the rocks in the area where they are found are possible oil source rock
حيث توضح هذه الاحداث السطحيه والتحت سطحيه انواع الصخور الموجوده فى هذه المنقطه المراد حفرها ومن ثم يعطى انطباع عن مدى وجود واحتماليه وجود الصخر الذى يعتبر بمثابه الصخور المصدره للبترول
They may indicate that economically important oil might have migrated from the rocks which contain these minor occurrences
تعطى هذه الاحداث معلومات عن هجره البترول وسريانه بين الصخور عن طريق تحليل هذه الاحداث السطحيه
They may indicate that they are on or near the edge of an important oil accumulation and thus these minor surface or subsurface occurrence may lead to amajor discovery nearby
Surface Occurrences
Seepages,Springs
Seepages,springs,imperegnated deposits ,bitumenous lakes and oil shales are common features of surface occurrences
petroleum as gas oil or liquid asphalt reaches the surface along fractures,faults,planes unconformities,joints,bedding plants or any connected porous opening in the rocks.spepages are mostly formed by the escape of petroleum in alarge quantities in the subsurface through these structural or erosional features
mud volcanoes and mud flows
Mud volcanoes is ahigh-pressure gas seepage the carries with it water,sands,fragments of rock,and occassionally oil
Many mud volcanoes and mud flows occur south of the central range on the island of trindad
Subsurface occurrences
Underground or subsurface occurances of petroleum may be
:divided according to their size into
Minor oil and gas showing
Oil and gas accumulations pools,fields,and provinces
Minor oil and gas showing
Some gas and oil are found in most wells drilled in sedimentary rocks many oil showings are on the borderline between commerical and non commericial to differentiate between them is one of the problems confronting every petroleum geologist concerned withe drilling wells .the oil and gas showings may be observed directly or by means of tests and logging methods
Oil and Gas accumulation
Commericial petroleum deposits are classified into pools,field and provinces
Oil and Gas pools
Pool is the simplest unit of commerical occurances of oil and gas accumulation
Its defined as the boody of oil and gas or both occurring in aseparate reservoir and under asingle pressure
Oil and Gas field
the group of pools related to one single geologic feature either structural,stratigraphie or lithofacial are called afield
Oil and Gas provinces
Apetroleum provinces is aregion in which anumber of oil and gas pools and fields occure in the similar or related geological
environment