Seismic Imaging - Revealing the Kingdom's Hidden Treasures

by Michael Ives

As Saudi Aramco expands the Kingdom’s conventional and unconventional oil and gas resources through discovery and reservoir development, cost-effective geophysical methods are being implemented.

Seismic is the most common method practiced throughout the industry, providing images of the subsurface that help reduce exploration risk and support drilling decisions. The company has been very active in acquiring seismic data for decades to image the promising hydrocarbon treasures beneath the surface throughout the Kingdom.

For a modern-day explorer, to drill without the guidance of advanced seismic data would be unimaginable. The journey of exploration at Saudi Aramco is a journey of seismic advancement, which for more than 85 years has enabled the company to be a practical steward of the Kingdom’s hydrocarbon resources. Over the past 50 years, the company’s seismic data has increased by a factor of 10 every decade, delivering knowledge of the subsurface that Max Steineke could only dream of.

The Quiet Heroes of Geophysical Seismic Imaging

Saleh A. Al-Maghlouth

At the center of this seismic data evolution, both the Eastern and Western Seismic Imaging divisions — which are composed of more than 100 data processors — deliver subsurface images to their partners in the Exploration organization. Geophysical Imaging Department (GID) manager Saleh A. Al-Maghlouth calls the seismic data processors in both divisions “the quiet heroes” of GID. “When we get data in from the field, we get huge volumes on discs or tapes and our seismic processors build a subsurface image from billions of traces. Using a multidisciplinary approach, physically and geophysically, they condition the data to give the most accurate picture of the subsurface as possible, harnessing some of the world’s most powerful computers and their own extensive skills,” says Al-Maghlouth.

The search for hydrocarbons since the company’s founding has been relentless. Saudi Aramco’s passion for new discoveries hasn’t changed, but the technology available certainly has moved from the physical to the digital, and from the tools of the industrial age to the incredible processing power that the Fourth Industrial Revolution now delivers.

Moore’s Law has been a guiding light in computing for decades, successfully predicting the doubling of processing power every two years. At Saudi Aramco, the evolution of the company’s ability to understand the subsurface mirrors these predications. With such technology and computing advancements, chief geophysicist Mohammed Al-Otaibi emphasizes that challenging geological settings, such as the Red Sea and the Kingdom’s Northwest, have been turned into opportunities through developing advanced algorithms to improve seismic images deciphering the quality of explored reservoirs.

The Eastern and Western Seismic Imaging divisions within GID have their imprints on every generated prospect when exploring for hydrocarbon resources over new areas. Mohammad A. Faqira, manager of the Eastern Area Exploration Department, says seismic is a key enabler in finding and quantifying hydrocarbon resources as it optimizes well placement with its laser-sharp pinpointing of well locations.

“This leads to cost saving by avoiding drilling dry wells, and cost reduction by optimizing the number of wells needed to delineate hydrocarbon discoveries,” he says. “Not using seismic is like trying to find something in the dark. Imagine how much time and money you would spend in exploring for hydrocarbons without better seismic data.”

Through advancements in seismic imaging, Saudi Aramco has been able to map subsurface areas across the Kingdom. With the growing amount of data being collected, it has refined the analysis of that data to more precise exploration of hydrocarbons, leading to far greater efficiency and reduction in costs.

Understanding Seismic

Fundamentally, seismic imaging is Exploration’s main pre-drilling tool, as drilling for oil or gas today without the work that the seismic processors undertake and the images they deliver would be the same as a surgeon undertaking an operation without the benefits of X-rays, MRIs, and other modern imaging tools at their disposal.

Seismic imaging is the most important because of its ability to detect both large- and small-scale subsurface features. Much like the way bats use echolocation to search for prey, seismic imaging involves the estimation of the shapes and physical properties of the Earth’s subsurface layers from the returns of sound waves that are propagated through the Earth. This form of seismic data can range from analog graphs and digital time series all the way to map texts. This data, which is enhanced through a set of computer intensive algorithms known as prestack time and depth migration, is used to create 2-D and 3-D images of oil and gas targets, built by the 100-plus strong team in the Eastern and Western Seismic Imaging divisions.

Geophysicists analyze seismic data at their workstation. From left are Moataz T. Sindi and Simon Evans.

To build the images of the oil and gas targets, huge volumes of raw seismic data must be processed. Gathering the data is but one piece of the puzzle, though, as it is the effective use of this data to build the imagery that is key to efficient exploration and cost control. This includes the complex task of designing a proper sequence of data processing — a processing flow. This is where the skill of Saudi Aramco’s processors in the Seismic Imaging divisions comes in, as no standard processing sequence exists that can routinely be applied to all types of raw seismic data.

Seismic processor Noor M. Al-Balawi, who has worked as a seismic processor for more than six years, notes how rewarding it is to be on the team, saying, “With the technology always evolving in such areas as automation, a step that once took one to two months can now be completed in one to two weeks.”

Yousef A. Al-Selais, another young seismic processor, agrees wholeheartedly. “From when I joined Saudi Aramco in 2011, I have seen a big increase in the quality of image we can deliver, along with the time it takes to put this together,” he says.

Members of the Geophysical Imaging Division are critical to the success of the company’s exploration efforts. Their analysis through review of remarkable amounts of seismic data and application of theories helps Saudi Aramco identify, locate, and extract hydrocarbon resources around the Kingdom.

Optimizing Data — Data From Anywhere

The task undertaken by Saudi Aramco’s seismic processors is a challenging one, transferring raw data into a form that is optimal (the best choice after considering all factors) for extracting the signal. They must make decisions, which rely on physical and geological theories, which tie the seismic data and geological problem together.

Geophysical consultant and senior processor Arun K. Sarkar says that raw data can come from anywhere across the Kingdom, including deep in the Empty Quarter to shallow water, with each environment presenting its own unique requirements. “I love the challenge of finding the right solution to deliver the best possible imagery, and I am incredibly lucky to love my job and go where my curiosity leads me,” says Sarkar.

His views are echoed by fellow senior processor and geophysicist Yazki Ibrahim, who has worked with the company over 13 years. “We are fortunate to work in the big picture of exploration, but we don’t work alone. We are in constant conversation with our clients,” Ibrahim says.

“For example, the Exploration organization may encounter a particular drilling challenge where we can assist. What is most rewarding is that we can see a project throughout from beginning to end. This is very different to working at a service company, where you would undertake a selected task for the client and then never hear of the project again. Being part of a bigger project where we are all working together to deliver the best results for Saudi Aramco, and ultimately the Kingdom, makes my role so much more rewarding,” he says.

Ibrahim notes that ultimately, it is about the combined power of working together “and combining skills from across the company, I get to bring together my two passions — math and physics — every day.”

Sarkar nods in agreement, “Here, we need to understand a wide range of disciplines. After all, in the study of the subsurface imaging through to exploration and eventually production, in my opinion, seismic processing is the foundation on which the successful and cost-effective delivery of Saudi Arabia’s hydrocarbon bounty is built. That is very rewarding to be part of,” he says.

Ibrahim goes on to note that the technology they work with every day has a long history, from being used in submarines in the 1940s, to use in CT scans, through to the big data subsurface modeling the team undertakes every day. “In the Northwest, I have seen the project going from initial seismic through to gas production that will eventually power the NEOM smart city and tourist zone. To play a significant part in such an important project and see it from the beginning has been a great experience,” says Ibrahim.

At the other end of the Kingdom, Sarkar notes he has been working on the offshore Manifa project for the past decade. “There is a huge amount of data still to be processed and our team is working hard to realize the value in this wealth of information.”

Sarkar says that Saudi Aramco has one of the largest seismic data processing centers in the world, “which makes sense as we are working on one of the largest hydrocarbon reserves in the world. That is always interesting.”

Geophysicist Fatimah M. Al-Bu Ali studied geophysics at Leeds University in the U.K., joined Saudi Aramco’s Professional Development Program (PDP) in 2015 and started her seismic processing assignment in 2017.

“The environment is very collaborative and professional. As a relatively new employee, I get exposure to the full spectrum of seismic imaging work,” says Al-Bu Ali. “For example, this year my focus is to work on generating accurate seismic depth maps for reservoirs, and next year, the plan is for me to focus on building accurate near surface models.”

Geophysicists review a seismic section, a key part of the exploration process. From left are Mohammad G. Otaibi, Yousef A. Selais, Duryodhan Epili and Omar Hassoun. ((Photos: Abdullah AlShammari/MPD)

Like Al-Bu Ali, her colleague Najoud S. Al-Otaibi also graduated from Leeds University with a bachelor’s degree in geophysics through a Saudi Aramco scholarship. Starting as a PDP, she also gained exposure across the business and eventually chose seismic processing as a career, in which she has now worked for close to one year.

“I now understand where the data comes from, and have the opportunity to build on my foundations as a geophysicist,” says Al-Otaibi. “I get the opportunity to work at the foundations of exploration, where we are, in effect, the roots of the tree that grows to be successful oil and gas production.”

Al-Otaibi, who is processing part of the Empty Quarter challenging seismic data, says what is particularly rewarding is converting raw subsurface seismic data into a useful image that can be used to make important business decisions, including whether to spend a significant amount of money on drilling a well.

“Delivering high quality, useable data to clients across the Exploration organization makes the job very rewarding. The atmosphere is so supportive, and the opportunity to also mentor younger employees, as well as being part of the decision making process through the Young Professionals Committee established within the Eastern and Western Seismic Imaging divisions, it really is a great place to work,” she says.

Unconventional Success

As the company pushes into its unconventional hydrocarbon resources exploration program, seismic data has been a key driver in the success in the Northwest and Jafurah basin. With limited subsurface data and complex geology in the Northwest, advanced seismic processing and imaging technologies were deployed to image the subsurface rocks layers. The efforts of seismic processing professionals were rewarded with the discovery of commercial quantities of natural gas, trapped within tight channel sands called “Sarah channels.”

In the Jafurah basin, seismic data processing also helped to predict changes in basin geological facies relative to the organic content, which defines areas to be evaluated. Seismic processing imagery was also used to create structure depth maps to place horizontal wells down to the level at which the rocks can be hydraulically fractured to release hydrocarbons.

“The success in discovering gas in Sarah channel sand is primarily driven by the effective utilization of advanced geophysical methods and proper data integration,” says Ahmed M. Al-Hakami, manager of the Emerging Unconventional Assets Department. “Such an approach is helping our teams unlock more promising gas opportunities, which can support the Kingdom’s gas demand.”

“The success in discovering gas in Sarah channel sand is primarily driven by the effective utilization of advanced geophysical methods and proper data integration,” says Ahmed M. Al-Hakami, manager of the Emerging Unconventional Assets Department. “Such an approach is helping our teams unlock more promising gas opportunities, which can support the Kingdom’s gas demand.”

Reflecting on the efforts of the entire seismic imaging team, Al-Maghlouth notes, “The passion of every member of the team to provide the highest quality processing of the acquired seismic data is visible in the quality of imagery they provide to their clients across the business, in a true spirit of collaboration.

“We are fortunate to have access to cutting- edge technology and incredible processing power. However, above and beyond our software and hardware is ‘mindware.’ We are blessed to have an incredibly bright and professional team of geophysicists in both Seismic Imaging divisions. They are not only doing excellent work; they are also producing patentable ideas.”

Seismic Imaging Timeline

1938 | First Discovery
First discovery of oil in commercial quantities from Dammam No. 7.

1940 | Aramco Acquiring Seismic
Aramco was one of the first companies in the Middle East to start collecting seismic data suitable for computer processing.

1956 | Seismographs
Seismographs were sent to be analyzed in an analog processing center in Texas.

1964 | Seismic in DigitalForm
Seismic data processed on a computer, the system was faster. Aramco has installed a complete digital seismic computer system right in Dhahran.

1991 | 3-D Seismic
Saudi Aramco initiated its first onshore 3-D seismic survey program, at Abu Jifan.

2019 | IR 4.0
Using automation and advanced technologies to enhance the Seismic Image.

2019 - future | Full Waveform Inversion
Future subsurface mapping and characterization.

— The Arabian Sun: October 30, 2019 | Vol. LXXIV, No. 42