Seismic: pushing the boundaries in frontier exploration

When the early pioneers set foot in Saudi Arabia in the 1930s, their mission was simple: explore for oil. Those early years were fraught with hope and disappointment in equal measure — but persistency paid off. Their refusal to throw in the towel when the odds were stacked against them resulted in their breakthrough at Dammam Well No. 7, which along with subsequent discoveries, formed the opening chapters of the ever-evolving Saudi Aramco story.

1938: The success of the Saudi Arabian oil enterprise rests on Well No. 7. After five years of fruitless drilling, Well No.7 seemed like a dead end. After seeking advice from renowned geologist Max Steineke, drilling continued. Finally, on March 4, 1938, Dammam No. 7 starts producing 1,585 bpd at a depth of nearly 1½ kilometers.

Eight decades later, hydrocarbon exploration continues in the Kingdom — exploring, it seems, is weaved into the company’s DNA. But the methods now deployed for oil and gas exploration are a world away from those that were known to the early explorers.

Nothing demonstrates this better than seismic operations, and Saudi Aramco, through its Geophysical Data Acquisition Division (GDAD), is at the forefront. It’s a dynamic operation that pushes the frontiers on all levels; human and technological.

“These are exciting times to be in exploration,” noted Saleh A. Al Maghlouth, manager of the Exploration Operations Department. “We are exploring from North to South and from East to West and our GDAD team is at the heart of this. The development of the technology in seismic over the last few years is truly mind-boggling and amazing.”

In every sense of the word, seismic technology is quite literally, earth moving.

The 65-ton vibrator truck is the safest proven energy seismic source.

Quantum leap

It’s a colossal sight. The 65-ton vibrator truck stands deceivingly motionless in the desert sand. It is preparing to release a steel plated vibration platform that is attached to its chassis into the ground below. When the plate lands, it begins vibrating, causing a barely felt shake in the area around the truck.

The location is Turayqa, deep in the Rub’ al Khali (the Empty Quarter), an eight hour road trip from Dhahran. This is about as remote as it gets.

The resultant seismic waves created by the vibrations are the raw data that forms the core of Saudi Aramco’s seismic operations. The vibrator truck is the safest proven energy seismic source.

This is not how Max Steineke and company explored for oil. Right up until the 1970s, geologists would rely upon the structure of the outer surface in exploration zones to gauge the possibility of hydrocarbon traps below.

“They drilled in areas where they approximated,” noted GDAD chief geophysicist Turki Al Ghamdi. “Even with Dammam Well No. 7, they almost gave up. But with developments in seismic, the risks in drilling and finding nothing have been reduced significantly.”

In the decades following the 1970s, due in no small part to seismic technology, there has been something of a quantum leap in our understanding of what lies beneath in the subsurface. Seismic technology uses acoustic waves generated by vibrations to collect information and data.

The gleaned information from the acoustic waves offers a window into the world of the subsurface — a dream for geologists in bygone eras. As a result, across the Kingdom seismic crews are busy working around the clock in the quest to recover hydrocarbon reserves that remain dormant beneath the Kingdom’s surface. 

Turayqa is home to Seismo-76, a crew of nearly 900. The 24-hour operation is just one of 10 seismic crews across the Kingdom operating under direction from GDAD.

GDAD chief geophysicist Turki Al Ghamdi (center) with members of his team as they discuss seismic operations. From left are Van Do, Zuhair Al Amri and Fuad Al-Somali.

In the middle of nowhere

The sun has barely risen in Turayqa and already there is a flurry of activity in the camp. Jeeps are being revved up and equipment is being loaded.

Turayqa is home to Seismo-76 — a seismic crew of approximately 900. It is just one of 10 crews operating under the instructions and guidance of GDAD. As the day shift are preparing to head to the field, their colleagues on the night shift are heading to their sleeping quarters — a full night’s work behind them. This is a 24-hour operation.

Here, in this apparently barren desert land, a massive exploration operation is currently underway. This is unexplored territory for Saudi Aramco — true frontier exploration. The crew are miles from life, yet paradoxically, their operations are monitored and guided by GDAD in Dhahran. As with many instances in modern life, technology makes distance seem irrelevant.

“We collaborate closely with the team on the ground,” said Hussain Al-Ghanim, a geoscientist with GDAD. “We supply the ground crew with the coordinates and parameters for seismic exploration and they begin their work. Our job is to make sure we receive the highest quality data possible from the field.”

The location of the 10 Kingdomwide seismic crews is anything but random. Like pieces on a chess board, they are positioned and moved with strategy and planning.

“Our job is to manage the day-to-day tasks of the crew. We are the interface between the crew and the proponent,” said Zuhair Al Amri, group leader of field operations at GDAD. “We monitor the daily data production, Health, Safety, and Environment activities, and mobilization… we also receive the daily reports from the crews. Every day is different and things are not static or routine. We are using the latest technology and this is exciting.”

The loop goes like this: Geologists examine 2-D imaging of a suspected hydrocarbon trap. The results are positive, although far from conclusive, but justify the next stage: 3-D seismic exploration. GDAD is contacted and maps the coordinates and parameters of the exploration area after extensive planning and location analysis. A proposal is created and shared with the seismic team that deploys to the proposed exploration area.

Seismic testing now begins to gain a deeper understanding of the structure of the subsurface. Complex data is transmitted to GDAD on a daily basis, who work with other teams across Exploration to process and interpret the 3-D seismic data. The loop is now complete.

Data that would have previously taken 15 to 20 years to collate can now be consolidated in two to three years

The CX-508 “Concentrator” is the brain of all acquisition units. It supplies clock and power to connected Field Digital Units and it transmits data to a central unit playing a crucial role in acquiring seismic data.

State-of-the-art technology

The leaps in technology that facilitate seismic testing are phenomenal. At Turayqa, the crew is exploring an area that measures some 15,400 square kilometers (km2) — a staggering size.

The area is acquired by more than 50,000 “strings” that contain nine geophones each — nearly half a million geophones — the conduits for transmitting the seismic data. This is transmitted through fiber optic cables reaching more than 4,000 km in length. So advanced is the technology that if at any point a cable is cut or damaged, the data will reroute itself to another cable.

The data is fed through multiple frequency channels; previously there were only 24 channels available to pick up the seismic frequencies. Today, Saudi Aramco seismic operations have access to more than 50,000 channels. In addition, thanks to simultaneous “shooting” of vibration points, data that would have previously taken 15 to 20 years to collate can now be consolidated in two to three years.

“In 2004, we would do around 2,500 shots a day,” noted Al-Ghanim. “But now, thanks to simultaneous shooting, we can do 14,000 shots per day.”

The “shots” that Al-Ghanim refers to are sound waves that are picked up by the strategically placed geophones in the exploration area. The geophones send the sound waves to data collection trucks stationed at the exploration site.

All action from the field is done in real time with extensive quality control systems in place to ensure that data reaching Dhahran is as accurate as possible. In Turayqa, a quality control center filters the data received via the data trucks stationed at the exploration site. As a result, three terabytes of data — the equivalent of 3,000 gigabytes — is sent daily to GDAD for analysis and quality control.

It is this data that serves as the roadmap for searching for hydrocarbon traps, serving as the eyes to the underworld.

At Turayqa, the crew is exploring an area that measures some 15,400 km2. The area is acquired by more than 50,000 “strings” that contain nine geophones each — nearly half a million geophones.

Out in the field, data collected is analyzed before being sent to GDAD in Dhahran. Each day three terabytes of data is transmitted.

Economic sense

“Seismic is important for the company as it prevents us from drilling unproductive wells,” noted Chinwike Jeremiah, a seismic crew supervisor with GDAD. “It allows us to identify traps.”

Previous exploration methods could prove costly, with drilling rigs often sent to exploration sites without truly knowing the structure of the subsurface below. Now, drilling rigs are brought in only after extensive seismic data collection — significantly increasing the likelihood of hydrocarbons being found.

“Seismic takes a snapshot of the image over a wide area of the subsurface, which could give rise to several wells. If you bring in a rig without seismic it is like drilling blind — you lose money. Seismic allows drilling to target and get it right — there is no guarantee still, but it gives very strong indications,” added Jeremiah.

But with the varying terrains across the Kingdom come varying challenges. “You are given an area to explore and don’t know the terrain,” he explained. “It can be very difficult, like the Shaybah sand dunes. But you can’t have it all — if you do seismic in a city environment the logistics are easier — but you have the problem of noise.”

Whatever the terrain, the data produced by seismic operations has changed the game in exploration. Wider areas can now be mapped in record time. And as the technology improves, so does the quality of the data.

“Seismic has evolved tremendously mainly due to the contributions of theoretical geophysics,” said Al-Maghlouth. “Due to sophisticated mathematical formulas and digitization, now we can image at the foot level as opposed to hundreds of feet. This helps us to further streamline our interpretation of data making drilling more cost-effective and efficient.”

In fact, Al-Maghlouth explains that since 2005 there has been a 2,500-fold increase in the data generated by seismic operations. This increase requires teams from across the Exploration organization to be at the top of their game. The GDAD team works with the Exploration Computer Center, which provides the computing capability to process the data. All of the processing and analysis of data is done in-house, with company scientists even developing their own algorithms to solve complex data challenges. 

Staying at the forefront

And as seismic technology continues to advance, GDAD is ensuring Saudi Aramco remains at the forefront.

“We design the field parameters to image the geological targets in a survey,” noted Fuad Al Somali, GDAD Technical Support group leader. “We also ensure that we have the latest available technology in the most efficient way. All of our land 3-D crews are High Channel, High Productivity crews with around 50,000 operational channels. We are always on the search for new and better technologies. We have continuous discussions with industry leaders to test new concepts and technologies.”

Al-Ghanim added, “Seismic is exciting and challenging and each day the technology is evolving and developing. One thing is for sure, at Saudi Aramco we will always be at the forefront when it comes to seismic technology.”

Saudi Arabia has been blessed with an abundance of hydrocarbon reserves, and under the guardianship of Saudi Aramco, exploration continues — it’s the heart of the Saudi Aramco story.