Hydrocarbon prospect in Deep Offshore of Bangladesh

Hydrocarbon prospect in Deep Offshore 

Bengal delta is one of the active delta in world and Bangladesh is located within this deltaic region. Every year a huge load of sediment is carried by rivers flowing over Bangladesh and deposited into Bay of Bengal. The source of petroleum is plants and animals that died millions of years ago and the sediment of Bengal delta carries a huge amount of organic substance which lead to the generation of hydrocarbon through a process of sediment compaction, maturation and migration under certain pressure & temperature within the time span of million years. 

Oil & gas prospect in Bangladesh is very potential and have gas discovery through a belt from north east to middle to south eastern & south part of Bangladesh. Sangu gas field is only offshore discovery which is already shut down now. Oil discovery was only at Haripur in Sylhet and not in production track. Hydrocarbon is only energy that leads the world to modern civilization and show the way of development for a nation. Bangladesh is still at back on petroleum exploration and could not reach to an expected level of success in view of development. Bangladesh won the arbitration on International sea territory and opens a vast prospective area for oil & gas exploration in offshore. Hence Bangladesh Government may anticipate appreciation for their important role on arbitration and cordial gratitude to them.   

Geologically Mio-Pliocene (Time 1.65-23million years) formation is oil & gas bearing formation of Bengal basin and depth ranges from 3.0-5.0km from surface and can be less in deep sea, i.e. 2-3km from sea bed. Sea bed is below water depth and water depth ranges 1-1.5km at deep sea. Deep sea formation is not much affected by the recent deposited sediments as it is far away from depositional arch of shallow sea and hydrocarbon bearing formation will not be deeper at deep sea. Presence of high pressure in subsurface geology is the main barrier of drilling and very costly drilling as well. Tectonically Bangladesh is located in between subduction zone of Indian plate and Burmese plate. Tectonic feature in formation like major & minor fault, fracture, unconformity etc changes the reservoir of oil & gas as well as indicator of abnormal pressure which is most critical barrier of safe drilling. 

Tectonic force is one of the important reason lead discontinuity of rock formation and decompose the reservoir potential of formation. Need to mention that earthquake is the element of plate movement and not only damage the surface features but also smash up the rock formation by creating fault & fracture at underground affects oil & gas reservoir, migration of hydrocarbon and generate new abnormal pressure zone in formation. South, south western and western deep sea & nearby area of Bengal basin is likely a trough and consist of organic rich thick sedimentary rock covered by huge water body above sea bed may reduce the consequence of tectonic force to rock body of this area. Underground drilling hazard will also be less in rock formation of deep sea. Less hazardous formation will be favorable for drilling, may faster the drilling operation and reduce the cost as well for safe completion of drilling a well. Geologically south, south west and western part of offshore will be more favorable for drilling as the high pressure zone is gradually tend to deeper from north east to south west in formation of this part. 

Presence of hydrocarbon at shallow depth in Pleistocene (Time <1.65million years) formation is prominent in Gulf of Thailand. In Bangladesh offshore have possibility of oil discovery in Pleistocene formation. During drilling Sangu (7) B at Sangu platform observed traces of oil show at shallow depth around 950m-1100m from surface, is not reserve but possibly source. It suggests have prospect of oil reserve in Pleistocene formation of deep sea. Besides for any discovery of oil & gas it may need to justify reserve quantity and all expenses relate to production stage. So recoverable quantity and exploration & production cost of hydrocarbon is also important for declaration of any oil or gas field.  

From record very few offshore drilling in Bangladesh and limited data is not sufficient to analyze oil & gas reserve. So far from the deltaic nature, depositional history and sediment criterion it assumes deep offshore & adjacent area might be rich in oil & gas. It will not be very surprising a giant oil reserve is hiding beneath deep sea part of Bengal basin. Bangladesh is spending huge foreign currency on importing crude oil and pulling back sustainable development of country. It is now appropriate time to focus on petroleum exploration in vast offshore area with a great hope of discovery of black gold. 

          

Offshore Block Bangladesh