OPTIONS FOR COMMERCIAL GAS DEVELOPMENT OF MARGINAL FIELDS

Transcription

1 OPTIONS FOR COMMERCIAL GAS DEVELOPMENT OF MARGINAL FIELDS Gabriel N. Bujulu Principal Petroleum Engineer TANZANIA PETROLEUM DEVELOPMENT CORPORATION

2 PRESENTATION OUTLINE! Introduction! Origin of Natural Gas! Uses of Natural Gas! Gas transportation! Gas Occurrence in Tanzania " Songo Songo and Mnazi Bay gas fields!gas Utilization in Tanzania " Songo Songo and Mnazi Bay gas fields! Gas as Energy of the Future! Concluding Remarks

3 INTRODUCTION # Natural Gas " Mixture of light hydrocarbon mainly Methane with non-hydrocarbon constituents " Occurs as free gas or in Solution with crude oil or Condensate under Pressure " Originally considered as a nuisance during search for Oil " Removed by flaring

4 INTRODUCTION contd.. # Natural Gas " Becoming World s most important Fuel Today and Future " Cleaner burning Source of Fossil Fuel " Better than Oil and Coal " Solution to Climate Change and Poor Air Quality

5 ORIGIN OF NATURAL GAS # Composition: "Methane, Ethane, Propane, Butane & Pentane hydrocarbon "Carbon Dioxide, Oxygen, Hydrogen sulphide and rare gases Non- Hydrocarbon

6 ORIGIN OF NATURAL GAS contd.. # Typical Composition: CH % Ethane C 2 H % Propane C 3 H % Butane - C 4 H % Carbon Dioxide CO 2 0 9% Oxygen - O % Nitrogen - N 2 0 5% Hydrogen Sulphide H 2 S 0 5% Rare gases He, Ne, Xe Traces Methane - CH

7 ORIGIN OF NATURAL GAS contd.. Origin: "Buried remains of plants and animals and micro-organisms organisms millions of years ago and subjected under high temperature and pressure results thermogenic Methane "Methanogenic or Biogenic Methane transformed organic matter by tiny microorganism in areas void of Oxygen (reducing environment)

8 ORIGIN OF NATURAL GAS Contd.. "Abiogenic Methane: Same as Thermogenic Methane but formed by raising gases from Earth's Crust to the surface and interacting with minerals and reacts forming methane deposits at high pressures "Gas as well as Oil formed in source rocks, trapped in reservoir rocks and migration prevented by presence of seal or cap rock "Gas or oil reach surface when hole is drilled through cap rock to reservoir

9 GAS FIELD TYPES " Classified based on field size and presence of market " Large commercial gas fields -large field in size at least 5 Tcf -associated gas " Marginal fields -small in size below 5 Tcf -remote location " Commercial development of marginal gas fields will depend on favorable economics of the project

10 USES OF NATURAL GAS # Uses of Natural Gas are diverse " Power generation turbine fuel " Industrial uses process heat " Residential and Commercial " Manufacture of Fertilizers (Urea / Ammonia) " In Manufacture of Petrochemicals " In Transportation (CNG) " Gas to Liquid Conversion (GTL)

11 USES OF NATURAL GAS Electric Generation Residential Transportation 3% 18% 22% Industrial 43% 14% Commercial Natural Gas use by sector (source: EIA Annual Energy Outlook 2002)

12 GAS TRANSPORTATION # Pipeline - Piped Natural Gas (PNG) # LNG - Liquefied Natural Gas (LNG) gas cooled to F (-162( 0 C) at normal pressure

13 GAS OCCURRENCE IN TANZANIA Two Gas Discoveries a) Songo Songo gas field " Located about 300 km South of Dar es Salaam, Kilwa District, Lindi Region " Discovered in 1974 (SS #1) by Agip Spa Gas in Neocomian / Albian sands " Drilled a total of 9 wells " One well (SS #2) blew out " Five wells completed as gas producers " Reserve about 1trillion cubic feet (tcf( tcf)

14 GAS OCCURRENCE IN TANZANIA Contd.. b) Mnazi Bay gas field " Located in Mtwara Region " Discovered in 1982 by Agip Spa " Gas discovered in Deltaic Oligo- Miocene sands " Reserves about 0.5 tcf up to possible of 1 tcf

15 GAS UTILIZATION IN TANZANIA # Songo Songo Gas Field " Discovered about 30 yrs ago " Songo Songo project began in 1994/5. Project construction activities completed in June " Commercial operations date for the project reached on July 21, 2004 # Uses: " Power generation start up 115 MW to increase to around 185 MW by mid 2005 " Industrial uses Wazo Hill, Kioo,, TBL, ALAF Bora, Nida,, etc. " CNG for Vehicles (dala( dalas,, taxis) " Domestic use

16 Songo Songo Wells Location

17 Songo Songo Onshore Gas Well Head

18 Songo Songo Offshore Gas Well complete with production platform

19 Aerial view of Songo Songo gas processing plant

20 Songo Songo Natural gas reserves Audited Recoverable Reserves (Audited by Gaffney Cline and Associates 2003) Proven 444 BCF Proven & Probable 639 BCF Proven, Probable & Possible 818 BCF New reserves audit by GCA in progress to be ready May 2005

21 Songo Songo Pipeline Route

22 Gas Marketing and Distribution in Dar es Salaam $ Apart from power generation Songo Songo gas is used in industries $ Constructed distribution network within the city In phases with phase 1 complete Using HDPE pipes 3 industries already on gas

23 PAE Ring Main

24 GAS UTILIZATION IN TANZANIA Mnazi Bay Gas % Power Generation %Small LNG

25 GAS AS ENERGY OF THE FUTURE # Demand for Gas to increase in coming years # Natural Gas to play major role in Future " Cleaner fuel and has diverse uses " Very abundant Worldwide 176 trillion cubic meters (6200 tcf) ) (BP -2004) " GTL - conversion gives very clean fuel " Stranded/marginal Gas fields development LNG facilities GTL Units

26 SUMMARY AND CONCLUSION " Natural Gas cleaner fuel hence increase in demand " Tanzania has witnessed the first gas development in East Africa in Songo Songo Gas Field development commissioned in late July 2004 " Songo Songo Gas for Power Generation and Industrial use " Dar Industries have shown high interest for conversion (three industries already on gas)

27 SUMMARY AND CONCLUSION Contd.. # Mnazi Bay gas for power generation, small LNG # Gas resources in Tanzania as well as other East African states, has Market # Challenges ahead is to find more Gas # Encourage more Gas use to improve environment

28 THANK YOU FOR YOUR ATTENTION