Geopressure signify potential hydrocarbon reservoir in offshore
Petroleum is leading energy source and will dominant as prime source for next 2-3 decades. After 2050 petroleum may loss it’s top position as raw energy source and may decline consumption of petroleum all over the world. Consequently petroleum will no loger be the primary object of energy generation and will reduce the worldwide hydrocarbon exploration activities. Only for late decision of offshore exploration it may remain unexplore vast offshore area of Bangladesh, whilst the offshore drlling technology will be insufficient and costly. Geologically Bangladesh is located at mouth of active Bengal delta and in the subduction zone of Burmese plate and Indian plate. Hydrocarbon reserve in this deltaic region has great effect of plate tectonic movement, very rapid and juvenile sedimentation process and undeformed compaction of sediment. For hydrocarbon exploration drilling is ultimate method for extraction of oil and gas from reservoir and it is most important to analyse subsurface formation, related positive or negative geopressure anomalies and ultimate status of petroleum reservoir. It is now possible to view the petroleum province within an overall geodynamic picture resulting from an integration of structural deformations, sedimentary changes, heat flow, fluid transfer or migration etc. In fact all are intimately linked and a variation in any one parameter acts on all others, constitute the petroleum system. Geopressure and its superficial effects has long played an important role in petroleum exploration. There is always an element of risk with any drilling operation but the presence of abnormally pressured sequences can significantly increase these difficulties, successful drilling requires the use of every means of detection at our disposal. Hydrocarbon exploration and petroleum reservoir characteristics in bengal delta is much more affected by geopressure anomalies and before drilling need analysis the regional geology of prospect area. Hydrocarbon reservoir does not depend on artificial man made boundary of country but depends on regional geological history. Hence, discussing hydrocarbon reservoir status in coastal and offshore part of Bangladesh considering subsurface geopressure of regional geology. Bengal Basin is part of Myanmar, Bangladesh and India and basinal part of Bangladesh is relatively at down slope of Myanmar and in middle of Bengal basin. Sedimentary thickness of Bengal basin is almost 20-22km thick and in the form of arch and synclinal basin design represent more sedeimentary thickness. Resulting force of plate movement has great effect on sedimentary bodies, twist the sedimentary body into different sub structure like fold, fault, fracture etc. Sedimentary body of southern part of Bengal basin is divided into two types of structural view by thrust fault, i.e. uplifted south eastern fold belt and north western plain land with southern coastal and offshore part. South eastern fold belt is highly compressed and pressurized rock body. High compression makes fault and fracture inside formation affects the hydrocarbon reservoir, seal and migration. South eastern uplifted fold belt and adjoining area is quite unpredictable for high intensity of geopressure anomalies. Hydrocarbon of this area especially natural gas could leach to nearest closure or even can be out through surface feature linked with internal fracture or fault of rock sequences. From limited scope a study of regional geo pressure is made from nearby offset well data of coastal and shallow sea of Bangladesh. Above figure represents actual status of geo pressure and hydrocarbon reservoir in this area. In Bangladesh hydrocarbon reservoir is mainly in formation of Mio-Pliocene age above identified over pressure zone. It shows Semutang, Halda and Magnama is highly compressed and pressurized and subsurface is greatly affected by fault and fracture and geo pressure is upward with depth. The Indo-Burman range is located to the east of Magnama and passage by Semutang and Halda marks the nearby zone of plate collision. By the Late Eocene time the direction of Indian plate convergence changed from north to northeast with increasing collision with Southeast Asia. Deformation is strongest as plate move north eastwards towards the Indo-Burman Range. This is evidenced by the increase in shallowness of over pressured zone. South Eastern fold belt and adjoining coastal area will not be good hydrocarbon reservoir as commencing high convergence, high angle inclination and less extension of sedimentary sequences, affected factor of plate tectonics and very close to subduction zone. Drilling in this area might be less prospective and hazardous. Sangu, Kutubdia, Sandwip, Shahbazpur, Hatia, Sonadia and Char Kajol is comparatively at down slope of coastal area, gently sloping down to south and southwest direction towards offshore and is relatively far away from the Indo-Burman Range and less affected by plate tectonics. Most structures are hydrocarbon charged and some of the drilled wells in this area are in production track. Nearby location like CharJabbar, Manpura, Bhola and adjoining structures are highly prospective for hydrocarbon considering regional geopressure trend and geological criteria. Over pressure of BODC and Bina well location is relatively deeper and almost has no effect of plate tectonics. South western Bengal basin of Bangladesh part can be affected by Barishal-Chandpur gravity high and hydrocarbon reservoir in this area can also be affected. Though do not have available data of this region but assume offshore will be hydrocarbon rich area. Comparatively geopressure trend is gently sloping down from south eastern coastal region to deep offshore of Bengal basin in the direction of south and southwest. Thick sedimentary sequence with overlying water body of deep offshore area is less affected by plate tectonics and has wide extension of rock formation can be indicative of good hydrocarbon reservoir. Sedimentary rock of Bengal basin is organic rich, hydrocarbon maturation time and migration is also favorable for hydrocarbon generation. As less effect of plate tectonics in sedimentary rock sequence of deep offshore area may have possibilities of oil discovery in Pleistocene formation at shallow depth and Mio-Pliocene formation above over pressure will be highly prospective for hydrocarbon. For hydrocarbon exploration seismic data acquisition is primary procedure for defining sedimentary structure of hydrocarbon reservoir. In this regard qualitative data acquisition is most important for proper analysis facts that work in offshore are quite expensive and hazardous. In view of qualitative data acquisition Multi client seismic survey will not be authentic rather have possibility of data manipulation considering the liability of risky offshore work. Manipulated data will never represent the real subsurface feature on reverse it may misguide the expensive exploration work. Better option is search for IOC and proceeds for offshore bidding & move on details negotiation for signing PSC (Production Sharing Contract). Seismic data acquisition in offshore under PSC will be more qualitative as cost recovery is related with hydrocarbon discovery of respective offshore block. Rezaul Kabir, is a petroleum geologist and an international oil & gas exploration specialist.
‘Energy sector’s paradigm shift over past decade’
Energy and power sector over the past decade has witnessed paradigm shift. Gone are the days of chronic power load shedding. But sustainable supply of quality power supply as well as assured supply of primary energy remains a huge challenge. Sheikh Hasina led-government of grand alliance has completed second consecutive terms of five years each in state power. Count down has started for the general election for electing the next government. Observers, experts, analysts and critics are reviewing and critically analyzing the performance of the government in different sectors. Energy and power sectors are two very important areas where government performance can be summarized as mixed success. There are commendable successes in some areas and at the same time major failures in other areas. Even the bitter critics of the government would acknowledge that the diabolic power load shedding situation is nonexistent now. Government through various efforts could redouble power generation. Bangladesh no longer suffers from 10-12 hours unbearable load shedding. At the same time even the staunchest supporters of the government would not hesitate in agreeing that fuel supply situation remains in crisis. Energy and Mineral Resources division (EMRD) and Petrobangla have failed to exploit discovered coal reserve, explore and develop petroleum resources appropriately and even delayed in importing liquefied natural gas (LNG). Most of mega imported fuel based large power generation plant projects are running 3-5 years behind schedule. A significant portion of installed power generation capacity remains idle for fuel supply deficit and transmission and distribution systems constraint. Continuation of speedy power generation and energy supply act adopted as contingency measure still continues. Achieving about 12,000 MW actual power generation capacity in 2018 from about 3,500 MW in 2009 is definitely a major achievement but failure in achieving sustainable fuel supply capacity worries about achieving sustainable energy security. On the back drop of above parties and fronts aspiring for forming government after winning the upcoming general election must have a clear vision and strategy for achieving sustainable energy security essential for keeping the very impressive economic development going. In 2009 when this government in the last term came to state power massive power load shedding of 10-12 hours brought economic activities almost to stand still. The actual generation and supply came down to 3,200-3,500 MW against demand of 5,500-6,000 MW. Crisis was there for natural supply as well. Against a demand of 2,200 MMCFD gas production was 1,700 MMCFD. Natural gas accounted for about 90% of power generation. Natural gas also supplied raw materials to fertilizer and fuelled most of the industries. Government adopted short, medium and long term power generation plan for confronting and overcoming crisis. As quick fix under contingency planning liquid based rental and quick rental plants were given go head adopting special power generation and energy supply act. Most of the furnace oil and diesel based power plants were planned to remain operational for 3-5 years from 2010 and private sector developers were selected under special power act as crisis management endeavor. Industries were allowed setting up captive power generation units. These initiatives worked wonderfully well in managing crisis and by 2014 situation came under reasonable control. The pace of impressive GDP growth could be sustained. The lowering price of crude oil in global market during this period also helped. But at the same time due to flawed planning and poor management almost all the base load traditional fuel based (imported coal and LNG) power plant projects failed to come into operation on time. Government has been forced to continue with contingency liquid fuel based power plants and rather expand capacity instead of doing away with these as scheduled by 2015. In PSMP 2010 the planned contribution of liquid fuel based generation was 6% and in PSMP 2016 it is planned to be 5% in 2030. But now it is about 35% and growing. The present increasing trend of price of crude oil in global market has already created concern of policy makers. Government over the entire two terms of ten years failed to exploit the substantial reserve of superior quality coal reserve. Neither, it could achieve any notable success in exploring new petroleum resource at onshore frontier areas and offshore. The proven discovered reserve of gas is alarmingly depleting. Government also made long delay in importing liquefied natural gas (LNG). Starting in 2010 import of only 500 MMCFD LNG is possible by end 2018. Government desperately needs commencing coal extraction and expediting exploration of petroleum. At the same government needs expediting all projects for setting up enabling infrastructure for fuel (Coal and LNG) import. It also needs to implement aggressive plan for developing competent human resources for planning, implementing, operating and maintaining energy and power projects. Power Scenario: Installed Capacity (31 October 2018): 20,430 MW Grid Connected: 17,340 MW Off Grid Captive: 2,800 MW Renewable: 290 MW A. Public Sector: 8,986 MW Companies Installed Capacity (MW) BPDB 5,266 APSCL 1,444 EGCB 839 NWPGCL 1,211 RPCL 77 BPDB+RPCL JV 149 Sub Total 8,946 (52%) B: Private Sector: 8354 MW Companies Installed Capacity ( MW) IPPs 5,099 SIPP ( BPDB) 99 SIPP ( REB) 251 15 Years Rental 169 3-5 Years Rental 1,576 Power Import 1,160 Total 8,354 (48%) In power value chain generation is only one segment and installed capacity is nameplate capacity. The 20,430 MW installed capacity for planning purpose is only a number. In existing circumstance it could be tested. What matters most is the actual highest generation and average generation. The highest generation ever achieved has been 11,623 MW during peak hours of 19, September 2018. PDB sources state of fuel supply deficit (natural gas) and constraints of power transmission and distribution system among reasons for leaving a significant capacity remaining unutilized, A maximum of 15 -20 % spinning reserve in a modern power value chain can be a right strategy. It appears from the table above that 2,800 MW off grid captive generation would not be ultimately there once industries have uninterruptible supply of quality power from the grid. 290 MW renewable power (solar) is also off grid. In future given access to grid through net metering rooftop solar and solar irrigation power can also make contributions to grid. Fuel Mix Scenario: Until the recent past natural gas almost exclusively dominated fuel supply for power generation and other industrial use. In view of the depleting scenario of discovered recoverable gas reserve and increasing demand of fuel for feeding economic growth government adopted fuel diversification plan in power system master plan 2010. 50% of the planned 40,000 MW power generation capacity targeted for 2030 was planned to be the contribution of coal. Local discovered coal was planned for 10,000 MW power generation. But government over the past 10 years failed taking political decision for mining own coal. As such the fuel mix planned in PSMP 2010 could not be achieved. PSMP 2016 re-fixed fuel mix. It targeted 60,000 MW power generation by 2041 with a planned fuel mix of 35% Coal (34% imported), 35% pipeline gas and imported LNG and 30% from nuclear, power import and others. No plan for local coal reserve exploitation is in view. Local exploration for petroleum resources in off shore and onshore is not up to expected level. Actual Fuel Mix Off Grid Connected Power (Installed Capacity): October, 2018 Fuel Installed Capacity % Contribution Natural Gas 10,138 MW 58.49% Furnace Oil 3,587 MW 20.69% Diesel 1,680 MW 9.69% Imported Power 1,160 MW 6.69% Coal 524 MW 3.02% Hydro 230 MW 1.33% Grid Connected Solar 23 MW 0.13% Reference: BPDB Website It can be seen from above that natural gas still dominates the fuel mix. But the proven reserve of natural gas is fast depleting. The exploration activities over the past 18 years remaining below bare minimum on the back drop of gas demand increasing in geometric progression has created huge gas deficit. Even responsible government policy makers apprehended that even at the present rate of use the reaming gas reserve may completely deplete by 2031 is not replenished with new discoveries. From 2000 to 2018 only about 1.5 Tcf new reserve could be added as against about 9 Tcf of proven reserve used. Deficit now is about 1200 MMCFD and growing. Off course 500 MMCFD RLNG supply very recently has comforted the situation a little bit. Gas Scenario: (July 2018) Gas Fields Discovered 27 Fields Under Production 19 Production Capacity 2750.00 MMCFD Highest Production (May 06, 2015) 2785.80 MMCFD Proven + Probable Reserve 27.77 Tcf Cumulative Production (December 01, 2018 ) 15.22 Tcf Remaining Reserve 12.55 Tcf Cumulative Peak Demand 3996 MMCFD Consumer 41.80 Lakhs Natural Gas apart from fuelling power generation is also used in fertilizer as feedstock, fuel for industrial, commercial, domestic and CNG. Gas Supply (July 2018) Sector % of Total Power (Grid) 40.22% Industrial 16.88% Domestic 16.03% Captive Power 16.32% CNG 4.75% Fertilizer 4.35% Commercial 0.84% Tea 0.10% Bangladesh energy sector is getting increasingly dependent on imported fuel, liquid fuel, LNG and coal. Some experts observed that if there is no major gas find soon and if local coal is not exploited Bangladesh may soon become 90% depended on imported fuel. Given the volatility of global fuel market and geo political uncertainties imported fuel dependency would create challenges in ensuring smooth supply chain, getting fuel and generating power at affordable cost. For fuel import Bangladesh needs setting up fuel import infrastructure–deep sea port, coal port, coal transfer terminal, LNG terminals, and liquid fuel import terminals. In addition government requires expediting exploration for petroleum in onshore and offshore. For Bangladesh a balanced fuel mix is recommended for sustainable energy security in the context of reliable fuel supply, affordability of fuel and power cost. For sustainable economic development sustainable fuel supply is prerequisite. We must bear in mind that world is fast moving towards green renewable energy moving away from fossil fuel. The carbon foot print of Bangladesh is negligible but we are among the most vulnerable country for climate change due to global warming. We have to plan our fuel mix according. Bangladesh has to adopt state of the art modern technology in power generation if they want to grow big in coal and other fossil fuel use. For that investment, price implications and extensive capacity development are major challenges. Geographical Location Presents Challenge: Geographically Bangladesh is sand witched between Indian states from almost 2.75 sides by Indian states. Mymanmar is on the South East and the Bay of Bengal is on the South. Bangladesh is a riverine delta formed of sediments flown in from the upstream by several rivers originated in the Himalyan Mountain and criss-crossing land surface in to the Bay of Bengal. The coastal area is relatively shallow unless Japan , Korea , India and China . The all season draft of Chittagong port is 8-9 meters and that of Mongla is 5-6 meters. Underdeveloped Payra port may not have more than 8 meter draft. For Coal carriers and LNG vessels at least 14 -16 all season draft is essential. Only in south of Matarbari Island it is possible setting up coal port and terminal and setting up land based LNG terminals. Till Bangladesh can set up deep sea port or complete the bay port terminal import of large volume of coal and LNG would remain a huge challenge. Investment and competent human resources are challenges here also. Saleque Sufi is an eminent energy expert.