Zim gas find needs minimal processing

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AS Zimbabwe urges closer to becoming a key player in the global natural gas industry, a growing source of energy across the world, one striking outcome from the recent compositional analysis of the petroleum deposits discovered at Invictus Energy’s Mukuyu fields in the northern part of the country was that the revelation that the hydrocarbon deposits contain minimal impurities.

This will limit the amount of capital outlay required to build processing facilities, reducing the period it will take to recoup the investment and enhancing the possibility of mobilising funding to rapidly develop refinery infrastructure.

The recent natural gas discovery, according to the Government of Zimbabwe, will bring about benefits that include electricity generation, production of liquid petroleum gas, fertiliser and petro-chemicals.

The Australia Stock Exchange-listed company said this week the results of the compositional analysis conducted by an independent expert in the United States, confirmed the discovery by the company of large natural gas deposits in the firm’s prospective area in the Cabora Bassa basin, further showing the fields had high-quality natural gas with minimal impurities.

Minimal processing

Natural gas processing is a range of industrial processes designed to purify raw natural gas by removing contaminants such as solids, water, carbon dioxide (CO2), hydrogen sulfide (H2S), mercury and higher molecular mass hydrocarbons (condensate) to produce pipeline quality dry natural gas for pipeline distribution and final use.

Invictus managing director, Scott MacMillan, said the impurities in the natural gas were less than 2 percent C02 (carbon dioxide), along with associated condensate, which is a form of light oil with a yield of around 14-22 barrels per million cubic feet and condensate American Petroleum Industry (API) gravity of 50-60.

“Condensate, which is produced along with natural gas, is a form of light oil and it has many uses, primarily in the form of feedstock for petrol and diesel and petrochemicals, so a high-value product that we get along with gas.

“In addition to that, the gas, because of high quality and minimum impurities will need very little processing in order to sell it to customers; so very pleasing from that perspective and the results have lined up with the geological modelling to date that we have across the basin.

“We have more dry gas from the north of our licence area and more liquids and with oil in the south of our licence area, which has been evident as well from the Mukuyu-1 result,” he said.

Invictus said Helium and hydrogen were also confirmed in the gas stream.

Helium is a chemical element whose liquid form is used in cryogenics (its largest single use, consuming about a quarter of production), and in the cooling of superconducting magnets, with its main commercial application in MRI scanners.

Helium’s other industrial uses include — a pressurising and purge gas, used as a protective atmosphere for arc welding, and in processes such as growing crystals to make silicon wafers — account for half of the gas produced.

McMillan said Invictus was preparing a range of activities, with the company now in the design phase and preparation for a flow test for Mukuyu-2 “that will provide us information on the well deliverability as well as potentially connected volumes to that well‘’.

He added the ongoing process will assist with future phasing and planning of the production wells in conjunction with a 3D survey over the Mukuyu field, which will help us delineate the sub-surface in more detail.

“At the moment it is only mapped on 2D data and 3D data will result in much better improvement and understanding of what is going in the subsurface and also help us plan our location to pitch our future wells and concentrate on areas of the field for the fast-track development that we are planning for the future.

In December last year Invictus executed an updated gas supply memorandum of understanding (MoU) with local firm Mbuyu Energy for the latter’s proposed 500-megawatt (MW) gas-to-power project.

The Australian firm intends to supply the gas for the project from its 80 percent-owned and operated Cabora Bassa Project after the company discovered the natural gas discovery at Mukuyu fields.

Further exploration will be done in the firm’s expansive licence area across Muzarabani and Mbire districts in the north of Zimbabwe.

Zimbabwe faces an acute shortage of electricity, as demand far outweighs supply, which is managed through rolling cuts from the grid, causing serious disruption to economic and social activities across the country.

Demand for power in Zimbabwe peaks around 2 200MW-2 600MW, depending on season, while supply currently averages about 1200MW-1400MW, assuming new generators installed at Hwange Power Station are running at full throttle.

Types of natural gas

Crude oil wells: Natural gas that comes from crude oil wells is typically called associated gas. This gas could exist as a separate gas cap above the crude oil in the underground reservoir or could be dissolved in the crude oil, ultimately coming out of the solution as the pressure is reduced during production.

Condensate produced from oil wells is often referred to as lease condensate.

Dry gas wells: These wells typically produce only raw natural gas that contains no condensate with little to no crude oil and are called non-associated gas. Condensate from dry gas is extracted at gas processing plants and is often called plant condensate.

Condensate wells: These wells typically produce raw natural gas along with natural gas liquid with little to no crude oil and are called non-associated gas. Such raw natural gas is often referred to as wet gas.

Coal seam wells: These wells typically produce raw natural gas from methane deposits in the pores of coal seams, often existing underground in a more concentrated state of adsorption onto the surface of the coal itself.

Such gas is referred to as coalbed gas or coalbed methane (coal seam gas in Australia). Coalbed gas has become an important source of energy in recent decades. – Business Weekly