Petroleum

Guyana is divided into two Petroleum Basins named Guyana and Takutu, respectively.  The Guyana Basin is further divided into two basins, Onshore and Offshore.  Herein is a synopsis of the Basins.

Onshore Guyana Basin

The deepest part of the southern “boundary” is some 150 miles from the Guyanese Coastline. NABI Oil And Gas, Inc. and ON ENERGY Inc. companies have concessions within this part of the Basin.

Within the Onshore Guyana Basin, there was a chance of these blocks being subjected to competitive bidding, however this does not take away any one’s prerogative to apply for concessions within this area.  There were 13 wells drilled within this part of the Basin from 1916 to present day.  Only Rose Hall-1 drilled in 1941 and Drill-1 in 1967 had oil shows.  The eastern part of the Onshore Guyana Basin has the largest thickness of sediments reaching some 2,500 m.  It should also be noted that the gas found on the coast is nearly all biogenic, with a very small area yielding thermogenic gas. 

Offshore Guyana Basin

REPSOL, ANADARKO, ESSO/HESS/NEXEN, Mid-Atlantic Oil and Gas, Inc., RATIO Energy/Guyana Ltd and CGX Resources Inc. have petroleum concessions in this part of the basin.  Presently, a number of companies are negotiating for concessions in the offshore Guyana Area.

On the aspect of Offshore Guyana Basin, from the nearshore to around 80 miles to the north, the seabed is generally on the continental shelf then it moves to the slope and as one gets further it reaches the deep-water area.  From the northwest (where the Anadarko concession is) to the Northeastern area depths can be from 1,000 feet to more than 10,000 feet.  This area is known as the “ultra-deep waters”.  In May 2015, ESSO made a significant discovery of petroleum while drilling in its Stabroek Block.  

Guyana has never had a commercial petroleum discovery, although there are a number of wells that had oil and gas shows both onshore and offshore.  Prior to the ESSO discovery, our “best” well has been Karanambo-1 well drilled by Home Oil in the Takutu Basin in 1982.

Takutu Basin

Located in the southwestern area of Guyana lies the Karanambo-1 well, which was drilled in 1982 by Home Oil Company. This was the best prospect drilled within this Basin.  Located in southwestern Guyana a small amount of light crude was accrued.  Tests conducted on samples from Karanambo-1 found that the oil is of good quality (420API) and is of a “sweet” variety, that is, it contains less than 0.5% hydrogen sulphide.  However, its geological characteristics are mainly naturally fractured reservoirs, thus proving more difficult to find commercial petroleum than regular reservoirs.  The other wells drilled in the Takutu are Lethem-1 (1980), Turantsink-1 (1992) and Apoteri K2 well (2011). 

Petroleum

Petroleum includes all naturally occurring carbonaceous liquids such as crude oil, natural gas, and natural asphalts.  Petroleum is very common in small amounts and is widely distributed, however, it is rare that large accumulations that contain commercially important quantities are found.

Commercial accumulations of petroleum are dependent on technical, economic and political factors that influence whether an accumulation is worth developing in the existing circumstances.  Profitability is based on the following factors: 

  • Depth,
  • Geographic position,
  • Properties and amount of oil or gas,
  • Operations cost including drilling, production, and refining,
  • Price,
  • Fiscal regime, and
  • Political stability.

Base Terms

Petroleum Reservoir – A reservoir is a formation of mostly solid rock with tiny openings, or pores, which can hold fluids.  Reservoir rock usually contains hydrocarbons as well as water (mainly salt water).  Usually, these fluids are layered; gas (the lightest) on top, oil in the middle, and water (the heaviest) at the bottom.  It is preferred that reservoirs contain all three fluids; oil and gas are valuable minerals, and the gas and water often providing the driving force for oil to reach the surface.  This makes pumping unnecessary.

To accumulate a commercially valuable petroleum deposit, a reservoir must have the necessary configuration:

  • Porosity of 10% or more pore space,
  • Permeability of 10% or moreso that pores must be connected so oil, gas, and water can flow through it by moving from one pore space to another, and
  • The right seal and trap mechanisms that keep the petroleum from escaping.

Petroleum Geology

Geology is the science that deals with the structure and history of the earth and its life forms, especially as recorded in the rocks.  This science is essential to the petroleum industry, for it is used to predict where oil accumulations may occur.  Petroleum geology involves those aspects of geology associated in the discovery and production of petroleum.  Petroleum geology involves all aspects of geology and other related disciplines such as geophysics, paleontology, geochemistry, and other engineering fields.

The first principle is that the present is key to the past; i.e., the processes acting on the earth today are the same as those that operated in the past.

Some Statistics

Some of the Largest Oil Fields (based on future recoverable reserves) are:

  • Ghawar, Saudi Arabia - 75 billion bbl
  • Burgan, Kuwait - 66 billion bbl
  • Bolivar Coastal Fields, Venezuela - 30 billion bbl
  • Safaniya-Khafji, Saudi Arabia/Neutral Zone - 25 billion bbl

One of the Largest Gas Fields:

  • Urengoi, Western Siberia - 285Tcf (dry gas)

Petroleum Production Rates

Varies from 1 bbl/day (stripper wells) to more than 10,000 bbl/day.  Many stripper wells (they are so called because they produce from 1 to at least 20 bbl/d) are found in Oklahoma, Texas, Arkansas, and Louisiana, USA. 

Well Depths:

Well depths range from a few feet to 40,000 feet.  The deepest producing oil well is 22,000 feet in Southern Louisiana, and for the deepest producing gas well it is 26,500 feet in Oklahoma.  Most production is in the range of 2,000-10,000.

Careers

Drilling for petroleum on the coast of Guyana is based on an expectation that Petroleum evolved in the Guyana Basin Offshore. Guyana would migrate updip from the deeper parts of the sedimentary basin offshore, to the coastal fringe in the onshore. Most of the exploration work in the onshore coastal domain has been focused in the Berbice County since this is where the thickness of coastal sediments in which petroleum is expected to be found is the thickest. Westwards towards the Waini River, sediments become thinner.

Drilling is the end-point of an exploration concept that performs the test of where petroleum is present. In petroleum exploration, like solid minerals exploration, several methodologies are employed. Geological, geochemical and geophysical applications are the foremost technologies used on land but offshore, geophysical applications dominate.

Typical geophysical applications are aeromagnetics, which depend on the magnetic minerals in igneous basement rock to give a “picture” of the structural features of the basement to which the overlying sediment tends to conform. An aeroplane, flying at a fixed height, record signals from which a map of the broad regional features.

Seismic methods utilise energy waves into the subsurface that refract and reflect the formation boundaries and recaptured using a streamer. The recaptured reflections are processed as wavelets by computers and the end product is a cross-section of the subsurface of the earth showing the sequence of formation layers with the structural features. A study of a seismic map pinpoints targets for drilling.

Common geochemical applications test the soil for traces of hydrocarbons that have made their way to surface. Results from geochemical applications can be combined with the geology and geophysics to improve the chance of finding petroleum when a target is drilled.

The term “reservoir rock” is given to the rock types in which petroleum is found. Examples of these “reservoir rock” are sandstones, limestones, and dolomites.

Reservoirs of petroleum in the subsurface are created when the petroleum is unable to migrate upwards and escape to surface, and is contained in an area. The term “cap rock” is given to the impermeable rock type that prevents migration of petroleum. An example of such is shale. The term “trap” is a finite area where the reservoir of oil is contained in the subsurface and is the location that geologists look for to drill for petroleum.

Petroleum exploration is very costly. Millions of dollars are spent in this risky business. It also offers an exciting career in a technical science field. Geology, Geophysics, Geochemistry, Petroleum Engineering, Drilling Engineering, Geological Engineering, are some of the common professional areas that can lead someone into a career in a the petroleum sector. A solid foundation in science is needed, especially for the engineering professions.

There are also other career paths that could lead to a career in the petroleum sector; these are technology-based careers where someone could become especially competent in the instrumentation and methods for dealing with drill cores and samples, or operating a drill or conducting special surveys.

In such cases, the Petroleum Technologist is a sub-professional and works to the demands of the Petroleum Engineer or Geophysicist, for example.

In a fully developed petroleum sector, there are opportunities for many types of skills to be engaged. The Guyana Geology and Mines Commission is fully expectant that this will be the case as petroleum exploration expands.

Examples of Specialty Areas

GEOLOGIST

  • Maps the surface features of terrain
  • Interprets seismic and maps subsurface features therefrom
  • Is involved in well site activities

GEOPHYSICIST

  • Conducts remote methods for imaging the subsurface commonly utilising seismic, aeromagnetics, gravity

GEOCHEMIST

  • Analyses for existing chemical substances in the subsurface that could direct the explorationist to the prize

PETROLEUM ENGINEER

  • Is involved in most applied aspects of petroleum operations other than geological aspects
  • Reservoir modeling and analysis
  • Drilling and Production issues

DRILLING ENGINEER

  • Specialises in petroleum exploration and production drilling

Some other occupations in the industry

There are various skills needed in the oil and gas industry; skills needed for exploration, maintenance of existing wells, and for petroleum processing. This group includes exploration and production workers, executive, managerial and professional, clerical and administrative support workers.

The professions and what they do are given below:

Petroleum Engineers

  • Tries to understand the geologic formation and properties of the rock containing the reservoir, determine the drilling methods to be used, and monitor drilling and production operations. They design equipment and processes to achieve the maximum profitable recovery of oil and gas, often using computer models to simulate reservoir performance using recovery techniques.

Paleontologist

  • One who studies fossil remains at the study area.

Mineralogist

  • One who studies the physical and chemical properties of mineral and rock samples.

Stratigrapher

  • One who determines the rock layers most likely to contain petroleum

Photogeologist

  • One who interprets and examines aerial photographs of land surfaces

Drilling Superintendents

  • Supervises drilling crews, either one or more drilling rigs

Rotary Drillers

  • Supervises the crew and operate machinery that controls drilling speed and pressure.

Roughnecks

  • Help guide the lower ends of pipe to well openings and connect pipe joints and drill bits.

Roustabouts

  • Do oil field maintenance and construction work.

Party Chief

  • One who is in charge of the entire seismic operations especially in its daily administration.

Observer

  • Operates and maintains electronic seismic equipment.

Electricians, Welders, Instrument repairers, and laborers

  • Maintain equipment within the various areas of the industry.

Articles in Guyana's Petroleum Agreement

Click here for more details.

Petroleum Prospecting and Production Licences

Click here for more details.

Operating Procedure for the Exportation of Samples

Available Forms