Seplat Petroleum Development Company Plc, a leading Nigerian indigenous oil and gas company listed on both the Nigeria Stock Exchange and London Stock Exchange said the use of latest 3D seismic survey helped it revise upwards it oil reserves.
According to its full year 2018 report, Seplat’s Working interest 2P reserves as assessed independently by one of the largest, oldest and most respected reservoir-evaluation consulting firms Ryder Scott Company at 1 January 2019 stood at 481 MMboe, comprising 227 MMbbls of oil and condensate and 1,473 Bscf(254 MMboe)of natural gas which represents an increase in overall 2P reserves of 1 percent year-on-year.
“The main driver of the upward revision year-on-year is due to the incorporation of updated 3D seismic data into field reservoir models (in the case of oil) and the anticipated compression benefits resulting from upgrades to the Sapele gas plant,” Seplat said in its full 2018 financial report.
In 2018, Seplat’s working interest production of 49,867 boepd (comprising 25,669 bopd liquids and 145 MMscfd gas) was 35 percent higher than 2017’s working interest production of 36,923 boepd.
Investors would be happy to know that working interest owners also fully participate in the profits of any successful wells which stands in contrast to royalty interests, were an investor’s cost is usually limited to the initial investment, also resulting in a lower potential for large profits.
This is the first time Seplat is exploring seismic surveys however other International Oil Company (IOCs) have also started exploring the use of seismic surveys such as United Kingdom based Europa who announced earlier in March 2018 it had completed Pre-Stack Depth Migration (‘PSDM’) reprocessing of 770km2 of 3D seismic data over the Inishkea prospect, including the area of the Corrib gas field.
“In addition, Europa has purchased 1,544 km2 of released 3D seismic data shot over, and immediately adjacent to, the LO area, 5,000 km of regional 2D and 13 wells,” Europa said in a statement on its website.
Also, French energy giant Total said it planned on acquiring 3D seismic for Brulpadda well which is three to five times bigger than all the gas discoveries so far in South Africa which Consultancy Wood Mackenzie has said the prospect could hold up to 1 billion barrels of oil equivalent.
“After the confirmation of Brulpadda’s potential, Total and its partners plan to acquire 3D seismic data this year, followed by up to four exploration wells on the license,” the company said.
In the past, wells were drilled into the Earth where people had a ‘feeling’ that there could be oil- perhaps where oil seeps had been found nearby. Often, large folds of rocks, called ‘anticlines’, seen at the earth’s surface, were drilled in the hope that oil or gas may be trapped in the folds down below.
Now there are more scientific approaches, such as using a combination of the geology of an area, gravity and magnetic surveys, seismic surveys and remote sensing techniques like aerial photography and satellite imagery from outer space which help in pointing areas where oil and gas may be found.
However, seismic surveys are the most important modern technique for locating new oil and gas deposits. A seismic survey uses sound waves which are created just beneath the land surface or near the surface of the sea. The waves travel down through layers of rocks and bounce back like echoes. By using computers, geologists and geophysicists can build up an accurate picture of what is under the ground or seabed, and then figure out where oil and gas might be found.
Seismic pictures can be in 2D (a vertical slice through the layered earth), or in 3D (a whole cube of information about the layers inside of the earth).