geology

Saturday 30 April 2011

Abnormal drilling Blow out



1- Parker Drilling Rig 255 Bangladesh Blow out






 
2- BP Blowout One Year Later: Drilling Safety an Explosive Issue
 
                             BP Blowout One Year Later: Drilling Safety an Explosive Issue
WASHINGTON, DC, April 18, 2011 (ENS) - Hundreds of activists protesting fossil fuels marched to the Department of the Interior's headquarters today and swarmed inside, calling for the abolition of offshore oil drilling, coal mining and tar sands extraction. The demonstration was timed to mark the one year anniversary of the BP Deepwater Horizon blowout on April 20, 2010 that killed 11 workers and spilled 4.9 million barrels of crude oil into the Gulf of Mexico.
Police report 21 people were arrested, including residents of California, Georgia, Texas, Utah, Vermont, Wyoming, and Washington, DC.
"For all practical purposes, Louisiana and the Gulf Coast function as a third world resource colony within the U.S. For a hundred years, our people and ecosystems have been sacrificed to provide cheap energy and big profits," said Devin Martin, a native Cajun from southern Louisiana.
Protesters outside the Department of the Interior in Washington, DC, April 18, 2011 (Photo courtesy DC Rising Tide)
"We pay for the hidden costs of oil and gas with our health and our lives through air pollution, oil spills, and a completely corrupted state government. We already lose a football field of coastal marsh every 38 minutes, and now rising sea levels from climate change will put my home, including New Orleans, under water permanently."
Today's march and sit-in are a preview of Rising Tide North America's "Day of Action against Extraction" set for April 20. Protests by Gulf Coast residents fighting offshore drilling, Appalachians resisting mountaintop removal coal mining, Texas, Pennsylvania and New York residents opposing natural gas hydrofracking, Canadians fighting tar sands mining in Alberta, are planned. Protests also are slated for the UK, New Zealand, and Australia.
On the government side, the new Ocean Energy Safety Advisory Committee held its first meeting today, setting deepwater drilling safety, oil spill source containment and cleanup as its top priorities.
Chaired by former Sandia National Laboratory Director Dr. Tom Hunter, the committee is made up of 15 scientific, engineering and technical experts from federal agencies, the offshore oil and gas industry, universities and research organizations.

Dr. Thomas Hunter chairs the Ocean Energy Safety Advisory Committee (Photo courtesy Sandia National Lab)
The committee will advise the Secretary of the Interior through the Director of the Interior Department's Bureau of Ocean Energy Management, Regulation and Enforcement, BOEMRE. This is the agency that once was the Minerals Management Service until internal corruption was exposed in a report by the U.S. Inspector General last May, about a month after the BP well blowout.
The IG's report probed a culture of complacency and arrogance, where MMS executives accepted gifts, money, sports tickets, drugs, vacations, and jobs from oil corporations, including BP.
Renamed and reorganized last year under the leadership of Michael Bromwich, a former federal prosecutor and inspector general for the Department of Justice, BOEMRE is refocused on safety, says Bromwich.
"The Safety Committee is an important part of our continuing efforts to reduce the risks associated with offshore energy production on the U.S. Outer Continental Shelf," Bromwich said today. "I look forward to the committee's recommendations as we continue to move toward safer, more environmentally responsible offshore energy development and production."
But environmentalists say the agency has made only surface changes and remains too cozy with the people it is charged with regulating.
Interior officials admit there is much more to do before deepwater drilling is truly safe, but meanwhile, the federal government will contine to review drilling applications and issue permits.
In a speech Thursday in Washington, Bromwich said, "We will implement reforms necessary to make offshore oil and gas production safer. The processing of drilling permit applications and proposed drilling plans will not be delayed while these additional reforms are developed."
Interior Secretary Ken Salazar today urged committee members to work together to help strengthen the nation's offshore drilling safety, well containment, and spill response "as we explore new energy frontiers."

    Interior Secretary Ken Salazar, right, and BOEMRE          Director Michael Bromwich, second from left, tour Noble Energy's drilling rig, April 13, 2011. (Photo courtesy DOI)
"In the aftermath of the Deepwater Horizon oil spill, many have recognized the need for more collaboration among government, industry and academia to develop cutting-edge, effective, and easily deployable technologies for prevention, containment and response," Salazar said. "This committee, with some of the nation's brightest minds from all three areas, will facilitate future cooperation and assist the Department in implementing our offshore drilling safety reform agenda," he said.
Last week Salazar and Bromwich toured the first deepwater drilling project permitted since the Obama administration imposed a deepwater drilling moratorium in the wake of the Deepwater Horizon blowout - Houston-based Noble Energy's Santiago prospect 70 miles southeast of Venice, Louisiana, in which BP is a non-operating partner.
Noble spent two months drilling 13,580 feet below the sea surface before it had to plug the well under the moratorium.
Noble was the first operator to demonstrate in a permit application that it is capable of containing a subsea blowout if it were to occur. During a tour of the Ensco 8501 rig about to begin drilling the bypass well for Noble Energy, the two officials examined new testing systems and checked out a blowout preventer.
"The deepwater operations that are resuming in the Gulf of Mexico are meeting the stronger safety and environmental protection requirements we have set, including the requirement that companies show they are prepared to respond to subsea blowouts and spills," said Salazar.
The Ocean Energy Safety Advisory Committee is intended as a first step toward establishing the proposed Ocean Energy Safety Institute, which would facilitate collaborative research and development, training and execution in these and other areas relating to offshore energy safety going forward.
The committee will provide advice on how best to establish the institute, and on what role OESC should play as the institute takes shape.
The group's first meeting included presentations from three expert panels: on the findings and recommendations of the President's Commission on the BP Oil Spill, the investigations into the causes of the Deepwater Horizon blowout by the National Academy of Engineering/National Research Council Committee and the Chief Counsel of the President's Commission, and the lessons learned from the Deepwater Horizon containment and response efforts.

At the direction of the Unified Command, BP contractors burn off surface oil from the spill in the Gulf of Mexico to keep it from reaching shore, sending clouds of pollution into the atmosphere. June 13, 2010. (Photo courtesy U.S. Coast Guard)
Deepwater drilling companies are multinational corporations with operations around the world. To engage other countries in reducing the risks of oil spills from offshore deepwater drilling, the Interior Department held a Ministerial Forum last week to share lessons learned from the Deepwater Horizon oil spill and promote collaborative solutions.
Ministers and senior officials attended from: Angola, Australia, Brazil, Canada, India, Mexico, Netherlands, New Zealand, Norway, the United Kingdom, Russia, and the European Union as well as the United States.
"As Interior works to set the gold standard for our deepwater development, we look forward to collaborating with offshore oil producing nations on the development of cutting-edge projects and common standards," said Interior Deputy Secretary David Hayes, who moderated one of the sessions.
"It is important that we work together with our international colleagues to learn from each other and develop global containment capabilities," said Bromwich. "Today was an important first step in this effort, and I hope that we continue this conversation in the future."
James Dupree, BP regional president, Gulf of Mexico, was among those at the Ministerial Forum as part of the company's onoging effort to learn from its costly mistakes.
"Last autumn we made an ongoing commitment to share what we've learned and the experience we gained during the Deepwater Horizon incident response with the world," said Dupree. "We have shared our insights with regulators, participated in public forums, worked directly with industry bodies and published our lessons learned."
In February, BP joined the newly formed Marine Well Containment Company, MWCC. Headquartered in Houston, Texas, the not-for-profit, independent organization is staging state-of-the-art equipment in the gulf to contain spills.
Mobile offshore drilling unit Q4000 in position over the damaged Deepwater Horizon well as crews work unsuccessfully to plug the wellhead using a technique known as "top kill," May 26, 2010. (Photo courtesy U.S. Coast Guard)
Chevron, ConocoPhillips ExxonMobil and Shell founded MWCC, which now also includes Anadarko, Apache, BHP Billiton and Statoil - all companies with operations in the Gulf of Mexico.
"Joining the MWCC and bringing our capabilities and equipment to an interim response system is another important part of that commitment," said Dupree.
MWCC's chief executive officer is Marty Massey, formerly with ExxonMobil Production. "Our objective is to ensure that the well containment response system is in a state of continuous operational readiness to facilitate rapid deployment and response in the event that it is required," Massey said.
MWCC's interim containment system is engineered to be used in deepwater down to 8,000 feet and has capacity to contain 60,000 barrels per day of liquid and 120 million standard cubic feet per day of gas with potential for expansion. It includes capping valves and dispersant injection capability.
BOEMRE has reviewed the functional specifications of the interim containment system, and its input has been included in the final specification.
BP will bring to the MWCC the riser, manifold and containment systems used during the Deepwater Horizon response. In addition to the transfer of equipment, BP will contribute the company's information and supporting records, drawings, permits, licenses and other technical information it developed throughout the spill response.
Oil production in the Gulf of Mexico accounts for 30 percent of U.S. oil and gas production and supports more than 170,000 American jobs.
{Editor's Note: Environment News Service has published close to 100 reports about the BP Deepwater Horizon blowout, oil spill and related legal and protest actions. To read any or all of them, click here, and type BP on the search line.}



Mudlogging Engineer My job and what I do

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 This mudlogging Engineer, he is Work in the Rig site and what   he doing ?





Wednesday 27 April 2011

Drill onshore Oil Rig


Oil and Gas Wells--Start to Finish



Drill offshore Oil Rig

                                         A look at Life on an offshore Oil Rig



                                           

Drilling abnormal or accident



Drilling abnormal or accident
1.Mud Gain
2.Mud loss
3.Pipe washed out
4.Bit worn out
5.percussion drill
6.Bit balling-up
7.Stuck
8.Bore hole collapse
9.Lost bit nozzle
10.Broken drilling string
1.Mud Gain

Phenomenon

  PVT increaseaccompanied with the change of  mud properties such as 
     density, conductivity, and viscosity, sometimes gas data increase.
     cause
      formation pressure >  pressure of mud columnformation fluid run into hole,
      Lead to well blowout.

 
2.Mud loss
Mud loss (circulation loss)
phenomenon
  pit volume decrease, a few to more than 10 cubic meters every hour, even to no return. If the loss velocity is high, SPP decrease.
cause
  Natural Geological ConditionsFor example, poor consolidated or unconsolidated,  and high permeability sandstone or conglomerate; It is easy to loss mud when drilling into fissure, fault or crushed zone caused by tectonism, solution cavity or fissure of carbonate formation.
  Improper Mud Propertieshigh density, high viscosity and high GELbe  difficulty to cuttings depositlead to high pressure of mud cylinder.
  Improper Drilling Activitiestrip in too fast or start pump and SPM increase suddenlylead to surge.
Lead to formation contamination bore hole collapse or stuck. It is often seen that well blow out after mud loss.
   
3.Pipe washed out
Pipe washed out
phenomenon
  other parameterssuch as mud properties, WOBFLOW INno change, SPP decrease slowly.
cause
  wear and tear of drilling string, at least, one hole come into being on drilling string at least. Some mud take a short way since the hole and run into annular.
Dangerous result
  bit balling up, even lead to stuckor drilling string broken.
4.Bit worn out
Phenomenon 
    WOB and RPM no change, drilling velocity become slow, TORQUE increase and  fluctuates in vast scale, cuttings become smaller. Sometimes see scrap iron.PDC, Tri-cone
          causebit life endbit teeth worn severely; If it is tri-cone bitsometimes cone movable.)
          Dangerous resultlose conelose bit   jet.
 
5.percussion drill
        percussion drill (Drilling string not well braked)
                Phenomenon:
                      suddenly, WOH decrease,  WOB increaseand   BLHT  decrease. At the                            same time,  instant ROP   increase drastically.
                                 Example 
                              Dangerous resultdamage bit and drilling string, some time get stuck.
 6.Bit balling-up
                       henomenon: 
                                suddenly, WOH decrease,  WOB increaseand   BLHT decrease. 
                                At the same time,  instant ROP   increase drastically.
                                Example
                                   Dangerous resultdamage bit and drilling string, some time get stuck.
  
7.Stuck
     
     Phenomenon: 
  •               when drilling string is still in the hole for some time, with no circulation, it is possible  to get sticy stuck. Drilling string can’t move, can’t turn;  can start circulation, SPP no change.
        Cause: the hole azimuth change and there is inclination or  drilling  directional    hole. Drilling string lie on the wall because of gravity and has big interface with wall. In permeable formation, much mud loss; mud cake thick and loose, and has high stick force. Long time still in the hole, drilling string will be pressed on the wall because of pressure difference between mud cylinder and formation.
            Solution: properly move drilling string up and down suddenly, force turn, or pump in diesel oil for unfreezing. If no success in unfreezing, back off and mill. 
             
        Stuck – because of cuttings deposit  
    
    phenomenonget overpull when moving drilling string up, can’t turn. Start pump, SPP increase, even choke the pump and difficult to start circulation.
               cause:(1Low mud viscosity and small mud shear force, during fast drillingstop pump since something happen. It is possible to get stuck because of cuttings deposit.
              2Low mud viscosity and small mud shear force, much mud loss, low mud salinity, seriously wash out, or did not fill in the mud in time when trip out, mud loss , blow out. All these things will lead to stuck because of  bore hole collapse.3Irregular hole diameter, stop pump suddenly,  it is possible to get cuttings bridge stuck in the place of big hole.
            Solutiontry to start circulation, properly improve mud viscosity and shear force. Increase FLOW IN slowly. If no success in starting circulation, back off and mill.
          Key-seating sticking
     
    Phenomenon:
       fixed stuck point, often happen when tripping out, can start circulation, SPP normal, drilling string can trip in and can’t trip out.
             causebad hole quality.
             solutionmove drilling string up with light overpull and back reaming with low RPM, use jars to unfreeze. If no success in unfreezing, back off and mill.
      tight hole sticking
     
     phenomenondifficulty to move drilling string up, and easy to move down; difficulty to turn when moving up and possible to turn when moving down. Start circulation, SPP increase little, stuck point fixed when trip in and trip out. After the drilling tools POOH, there is mud cake on the tie-in.  Example
              causeUnderground, for high temperature, plastic deformation happen to the rock salt,  lead to tight hole. High dilatability clay stone or shale meet water and swell to form tight hole.
              solutionif  it is rock salt leads to tight hole stuck, water flushing can be used; if clay stone or shale dilatability lead to tight hole sticking, can move drilling string and ream to unfreezing the sticking.
  
         Bit balling up sticking
      Phenomenon:  
              the bit turns unsteadily on the bottom of hole, accompany
              with bit bouncing, ROP slow, can move down or ream down. It is difficulty to move up and back ream, with abnormal circulation, SPP increase, even choke the pump.
              Cause: 1high mud viscosity, big shear force, high content of  solid phrase, low flow in, drill into soft formation, bit is easy to balling up. trip out to tight hole and it is easy to get stuck. 2Since drilling string penetrated, short circuit of  circulation; pump efficiency decrease or drill with no pump in. Bit balling up sticking is easy to happen.
              Solution: start circulationmove down and turn drilling string, properly decrease mud viscosity, shear force, and flush the bit with high flow in.

8.Bore hole collapse
Phenomenon:
          mud density, shear force, viscosity, sand content increase, SPP unstable, sometimes choke the pump, torque increase. Cuttings return to surface become more, and intermix, even include much cavings.
          mud properties unstable, change very soon. There is mud blow out from inside drilling string  when tripping in or tripping out.  
         Cause:
          geological causethere is abnormal pressure in the shale formation. When drilling into shale formation, the pressure of mud cylinder is less than pore pressure. The fluid in the shale run into the bore hole, accompany with flaking, cavings and collapse.
         Drilling techonicsthe washing of mud; high surge or swab lead to instant pressure unbalance; did not fill the mud when trip out, serious mud loss, well blow out, lead to bore hole collapse.
         Geophysical causeclay stone’s and shale’s hydration.
 
9.Lost bit nozzle
      Phenomenon:
                        flow in no change, SPP decrease suddenly, drilling velocity become slow.
 
  1. 10.Broken drilling string

   Phenomenon:
          when drilling, WOH, SPP, TORQUE decrease suddenlywhen tripping,     WOH decrease suddenly.
 


 
 


petroleum geology about Sudan

About Sudan

Sudan is a vast country of approximately 2.5 million square kilometres and a population of about 30 millions. Khartoum is the capital of Sudan lies at the confluence of the White Nile and the Blue Nile, both forming the river Nile, the longest river in the world, which flows into Mediterranean Sea. Sudan has common borders with nine countries in addition to the Red Sea coastline, which connects the country to the Middle East and Asia. As such Sudan is considered as an important gate to Africa. The climate in Sudan ranges from equatorial frost in the south to the great desert in the north.
Port Sudan is the main port of the country assisted by the smaller port of Suakin. Recently an oil export terminal of Bushier was opened in August 1999, see Fig (1).
The geology of the Sudan is extremely diverse and its interior basin evolution (Late Jurassic-Early Cretaceous) is related to the Central Africa Shear Zone.
Exploration activities started in the late fifties in the Red Sea and in the early seventies in the south central Sudan. Several hydrocarbon fields have been discovered offshore and onshore.
With the exception of the limited exploration efforts which have been put to evaluate the hydrocarbon potential of south central and west Sudan, most areas are considered to be largely unexplored.
The infrastructures for petroleum industry in the Sudan are in a good position now and it is continuously progressing.

Exploration History
Hydrocarbon exploration activities in Sudan date back to the late fifties, when the Italian Agip was granted the first exploration permit in the Red Sea. The company drilled 6 wells; non-of them considered a discovery.
The most important episodes in the history of exploration in the Red Sea basin are those of Chevron Oil Company (1975 – 1977) and the International Petroleum Corporation (IPC 1991-1996) with notably:
  * Three wells drilled by Chevron, two of them were considered dry Gas and wet Gas/condensate discoveries.
  * 1061 Kms. of 2D marine reflection Seismic lines were conducted by Geco Prakla for IPC, which enabled imaging of deep structures beneath thick salt and evaporite layers.
In 1975, Chevron signed a production sharing agreement with Sudan government to explore for oil and gas over a concession area (516000 sq. Kms.) in central and south central Sudan. After conducting extensive geological and geophysical works, Chevron started drilling operations, which let to the first oil discovery at Abu Gabra in 1979.
In 1980, Chevron discovered Unity oil field, followed by Heglig, Talih, Sharaf, Adar and Yale oil fields.
In 1980, Total Oil Company signed an EPSA with the Government for oil exploration in block (B). The company conducted geological and geophysical work and defined prospects for exploration drilling. Due to the break out of civil war in the southern Sudan, Total Company suspended its operations up to date.
In 1982, Sun Oil Company was awarded a concession in central and north central Sudan. The company drilled six wells, however, no significant hydrocarbon discoveries were encountered, hence Sun terminated its contract in 1990.
In August 1993, State Petroleum Company (subsidiary of Arakis) signed an EPSA with the Government over blocks 1, 2 and 4. The Company discovered very significant oil accumulations in Toma South, El toor, El nar and Um sagura fields.
In August 17, 1995, The government and Gulf Petroleum Company signed a Production Sharing Agreement for the development of Adar- Yale oil field (Block 3D).
In September 1995, the Government and the China National Petroleum Corporation signed EPSA over Block (6). The company has drilled three successful appraisal wells based on 3D seismic work, two of them in Abu Gabra field and one in Sharaf field.
In March 1996 a consortium group, which includes CNPC, PETRONAS, SUDAPET and SPC signed agreements for conducting upstream and downstream operations in blocks # 1, 2 and 4 originally acquired by State.
In Oct. 1998,Tilsman has taken the share of State Petroleum Company in the consortium.
In March, 12, 2000 a consortium of Gulf Petrolum Company (Sudan) Ltd., Melut Petroleum Company Ltd. and Sudapet Ltd. signed production sharing agreement over blocks 3D, 3E and 7E.
  FIG(6) shows part of  the petroleum infrastructures in the Sudan, which include the existing and under construction refineries, the crude oil pipeline route (L = 1610 KM., DIA. = 28 Inch, MAX. CAP. = 450000 BBLS/DAY) and  transportation means. In addition to these there are good communication means, airports, airstrips..etc.
The Sudanese Petroleum Data Center (SPDC) and the Sudanese Central Petroleum Laboratory (SCPL) are at their final touches to start furnishing services, to all oil companies working in upstream and downstream sectors, by the end of this year (1999).
The Sudanese Petroleum Corporation (SPC) and the Bureau of Geophysical Prospecting (BGP) have formed a joint seismic processing company, under the name the Blue Nile Processing Company Ltd. (BPC), and registered under the Sudanese laws.
The company is set up with objective of providing qualified 2D and 3D processing services for clients both in and outside Sudan. The annual processing capacity of BPC is up to 6000 Kms. Of  2D and 500 Km² of  3D, or simply 10,000 Km of  2D.

Out Line of Geology of Sudan
Structural Setting
The interior Sudan basins have been related in its evolution to the west and central Africa rift system, which was formed in Late Jurassic to Early Cretaceous. The shear stresses, which have been released as the result of the Global tectonic, which led to the separation of Africa from south America and the subsequent opening of the south Atlantic basin, has been transferred along the central Africa Fault Zone. The structural development of the Muglad basin is marked with three major rift cycles and sagging characterized with coarsening upward sequences of clastic sediments, those are:
·        Early Rifting; began in Late Jurassic – Early Cretaceous (130 – 150 MYBP). It is the strongest and lasted until near the end of Albian.
·        Intermediate Rifting; Senonian – Turonian. Development of rift lakes and deposition of lacustrine and flood – plain fine sediments (Aradeiba Fm.). It is associated with minor volcanism.
·        Late Rifting; Late Eocene – Oligocene. It is equivalent to the opening of the Red Sea and East African Rift.
·        Sagging; Middle Miocene, gentle subsidence and little faulting.  
The age estimates are poorly constrained by sparse palynological data.The recognition of the three rift cycles is based on identification of three regionally correlative depositional cycles which are particularly evident in the Muglad basin. Each cycle boundary is locally expressed by a subtle angular unconformity.
These movements led to the creation of a complex system of linked  extensional and transtensional sub-basins. The sub-basins typically have a half-graben geometry that was modified by subsequent reactivation during younger rift cycles. These grabenal structures trending generally NW – SE and arranged in an echelon pattern.
Muglad, Melut and Blue Nile are the three major sedimentary basins
Geological Setting.
 The geology of the Sudan Fig. (2) is extremely diverse with a variety of metamorphic, igneous and sedimentary rocks. Three metamorphic belts have been recognized, these are:
·         South Equatoria.Imatong Mountain.
·         Central Sudan and Nile Valley.
·         Red Sea.
 The intensity of deformation and metamorphism varies from place to place. Extensive studies were carried out by several workers, proved that the central Sudan and Nile Valley metamorphic belt include relic structures of ancient basement which date back to Lower Proterozoic or even Archean.
The oldest sedimentary rocks encountered so far in Sudan are of Cambro - Ordovician age? . These occur within narrow grabens formed by rifting, which preceded consolidation of Pan African structures in north and north-western Sudan, or as thin sedimentary cover (Sassa plain – Red Sea Hills) elsewhere entrapped within shallow underlying basement rocks.
Fig (2) shows the distribution of sedimentary basins in Sudan. Much attention has been given to explore the rift related basin systems, south central and central Sudan, while those defined by surface mapping and regional gravity work in central north and northern Sudan received less attention.
The gravity, seismic and drilling data acquired in interior Sudan basins indicated that more than 30000 feet of clastic sediments occur within the deepest central trough of the three major rift basins.
Fig(3), shows generalized stratigraphic columns for the Kaikang trough, which runs along the western flank of the Muglad basin and that of Unity in the Eastern flank, whereas, Fig(4) shows the stratigraphy of the Melut basin.
The sediments are interbedded sandstones, claystones, siltstones, mudstones and shales. Intrusive rocks (Sills) were encountered in some wells such as in
Garad – 1, Sobat – 1, Tabaldi - 1…etc.
Changes in lithofacies primarily reflect variations in the subsidence rates of various sub-basins. The lack of significant magmatism during active rifting, despite 20 to 30 KM of extension, is attributed to the shallow depth of fault detachments at a brittle – ductile transition of 12 to 16 KM.
Abu Gabra Formation is the main source rock, consists of dark lacustrine shales containing a typically waxy kerogen and proved to be a reservoir in block # 6. Bentiu formation, Darfur group sandstone members, Amal and Tendi formations are the principal reservoirs. Shales and claystones within
Darfur Group as well as shales and claystones within Abu Gabra Formation act as seal to underlying oil bearing horizons.
None of the wells drilled in the Melut basin, has encountered the source rocks, however, based on the crude oil biomarker distributions and characteristics, it is believed that the source rock in Melut basin is equivalent to the Abu Gabra Formation fount in the Muglad basin. Yabous Formation is the main reservoir in Melut basin.
Time of oil migration is uncertain, but it seems to be during mid to late Tertiary in the Muglad basin and during mid – Cretaceous to Late Cretaceous time in the Melut basin.
The present temperature gradients over these basins are normal and no over pressure zones have been recorded so far.

·         The Petroleum Resources Act 1998 and the Petroleum Regulations of 1973 regulate exploration and production of oil and / or gas accumulations in Sudan both onshore and offshore.
·         Major amendments have been introduced in the petroleum resource Act which give the Minister of Energy and Mining, with the approval of the Board of Petroleum Affairs, the right to conclude agreements for the exploration and production of oil and / or gas in the Sudan.
·         All the Agreements signed by the Sudan Government with the international oil companies are Exploration and Production Sharing Agreements (EPSA).The EPSA embodies the entire rights and obligations of the Government and the Oil Company.
·          The Oil Company, under the EPSA, recovers its operations cost from an agreed and negotiable percentage of the total production. The profit oil is divided between the Government and the Oil Company according to certain percentage to be agreed upon by both parties.
·         Equipment of the Oil Company used in petroleum operations are exempted from custom duties.
·         The oil discovered and exported by the Oil Company is exempted from any export taxes.
·         Exchange rights are provided for in the EPSA and the Oil Company is given the right to sell its share of oil and / or gas and keep the proceeds outside Sudan.
LICENSE POSITION IN SUDAN
The International oil companies operating now in Sudan includes:
·         Greater Nile Petroleum Operating Company (GNPOC).
The shareholders are CNPC (40%), Petronas(30%), Talisman (25%) and Sudapet (5%).
·         China National Petroleum Company (CNPC), 100% owner.
·         International Petroleum Corporation (IPC).The shareholders are IPC (40.375%), Petronas (28.5%), MOV AG(26.125%) and Sudapet (5%).
·         Gulf Petroleum Company – Sudan (GPC); 46%, Melut Petroleum Company 46% and Sudapet 8%.
·         Total EXPLORATION - Sudan, the shareholders are
Total Exploration (32.5%), Marathon Petroleum (32.5%), Kuwait Foreign Petroleum Exploration Co. (25%) and GPC (10%).
  The Ministry of Energy and Mining has adopted the blockage system. Since 1992, accordingly the Sudan basins were divided into a number of blocks based on the amount of geophysical, geological and drilling works done Fig (5) and table (1&4). Most of these blocks are free for contracting with any company or a group of companies, which are capable financially and technically to do the work. All data for free blocks are available in the Sudan.


Block No.
Block Name
Sub - Block
Area(SQ.km)
Operator
1
UNITY
1(a)
7173.26
GNPOC


1(a)
154.88
GNPOC
2
HEGLIG
2(a)
8628.62
GNPOC


2(a)
370.92
GNPOC
3
ADAR
3(D)
140.8
GPC,MELUT,SUDAPET


3(E)
10361

4
KAOKANG

32586.08
GNPOC
5
SUDD
5(a)
29885
IPC


5(B)
14643
C
6
ABU GABRA

38468
CNPC
7
MELUT
7(E)
61918.73
GPC,MELUT,SUDAPET
8
BLUE NILE

65856
F
9
KHARTOUM

128088
F
10
GEDARIF

57604
F
11
HUMRA

119124
F
12
MURDI

42888
F
13
DUNGUNAB

24600
F
14
ABYAD

135020
F
15
TOKER

28100
F
16
HALAIB

10300
IPC
17
C

65750
F
18
B

118.586
TOTAL