Perform a "CT" for the seabed to create a three-dimensional "portrait" of the seabed

Tech 2023-10-07 23:39:36 40 Source: Network

Recently, two offshore oil geophysical exploration ships in China were equipped with two domestically produced marine seismic exploration equipment - the "Haijing" system and the "Haimai" system, respectively, to carry out seabed geological exploration operations, providing "CT" and "Haimai" signals for the seabed in the operation area. What they have discovered and how to see the appearance of the seabed clearly is the focus of this section's "Technological Impetus"

Recently, two offshore oil geophysical exploration ships in China were equipped with two domestically produced marine seismic exploration equipment - the "Haijing" system and the "Haimai" system, respectively, to carry out seabed geological exploration operations, providing "CT" and "Haimai" signals for the seabed in the operation area. What they have discovered and how to see the appearance of the seabed clearly is the focus of this section's "Technological Impetus".

Exploring the geological structure of the seabed at a depth of 1500 meters in Heshan Depression

CCTV reporter Wang Shiyu from Taiwan:This is Offshore Oil Ship 720. More than a month ago, our exploration team worked day and night to complete all the exploration tasks in the deep and offshore waters in the Heshan Sag work area of the the Pearl River Mouth Basin before the arrival of the typhoon "Little Dog". So now we have arrived at the shallow sea part of this work area, with a water depth of around 1500 meters.

We plan to complete more than 1200 square kilometers of exploration tasks in this area in just over a month. This allows for a complete understanding of the entire Heshan Depression, covering an area of 2500 square kilometers.

We have learned from the geological exploration map of the 3000 meter seabed that there are also rivers and depressions in the seabed strata. According to estimates, there are abundant oil and gas resources here, making it a new exploration area for offshore oil and gas in China. Only through our high-precision surveying and mapping, can we accurately draw the "portrait" of the seabed, and know where these oil and gas are located. Provide support for future deep-sea oil and gas development, including the location selection of drilling platforms.

Gui Hongbing, Deputy Director of the Indoor Processing Room of China Oilfield Services Geophysical Research Institute:The exploration and development of offshore oil and gas fields involves a series of processes such as exploration, drilling, and engineering construction. As the saying goes, "oil and gas exploration go first", seismic exploration is a comprehensive "CT" scan of the deep-sea strata, and then a comprehensive analysis of the obtained data to obtain the true structure of our underground and discover oil and gas accumulation areas.

Geophysical exploration ships are equipped with the "Sea Economy" system to perform "CT" on the seabed

CCTV reporter Wang Shiyu from Taiwan:We have now arrived at the fourth deck of Offshore Oil 720, with ten submarine cables spreading out next to me. These ten submarine cables, each with a length of eight kilometers, are all deployed equivalent to 1400 standard football fields.

Zhang Gejun, Deputy Manager of Offshore Oil 720 Fleet:What is the 'Hai Jing' system like? I create an earthquake wave under the sea surface, which will transmit to the seabed. If the depth and structure of the seabed are different, the time and strength of the signal reflection will also be different. Based on the characteristics reflected by the signal, we can deduce the geological structure of the seabed.

CCTV reporter Wang Shiyu from Taiwan:What do we use to transmit signals? We arrived at the second deck of Offshore Oil 720. This row of high-pressure air guns is a device for transmitting signals to the seabed. It can be seen that there are four high-pressure gas cylinders at the front end of the deck. Each time a seismic wave signal is emitted, pressure exceeding 130 standard atmospheres is released, which enters the high-pressure gas gun through these pipelines and is then fired towards the seabed. With each launch, a large bubble forms on the sea surface, emitting 4000 to 6000 seismic waves every day.

Breaking the technical restrictions on imported equipment and achieving breakthroughs in "sea economy"

CCTV reporter Wang Shiyu from Taiwan:Let's now show you a comparison chart. Above is the results of past exploration, and below is the results of exploration in the same sea area using our independent "sea economy" equipment. It can be seen that there has been a significant improvement, as described by the staff, which is a leap from standard definition to high-definition.

China began marine geological exploration operations in 1964, when there were no professional geophysical exploration ships or equipment. Instead, balloons were used to pull explosives and float them into the sea to create artificial seismic waves for exploration. Around 2000, Western geological exploration equipment was introduced, and the depth of exploration operations reached 300 meters. In 2010, the depth of exploration operations reached 500 meters, and in 2020, it reached 1500 meters of ultra deep water.

Zhang Haonan, Deputy Director of the Equipment Research Institute of China Oilfield Services Geophysical Exploration Research InstitutePreviously, imported equipment had depth sensors, and once our equipment sank deeper than the limit depth, they automatically stopped working.

Haijing "is the first complete set of seismic exploration acquisition equipment independently developed and manufactured by China, and its successful use has also made China the third country in the world to master the technology of complete sets of seismic exploration equipment for towed cables.

Zhang Haonan, Deputy Director of the Equipment Research Institute of China Oilfield Services Geophysical Exploration Research InstituteIn the research and development process of "Haijing", we have broken through multiple technologies such as geophones, sinking depth and channel spacing technology limitations, and high-precision air gun synchronization control. The low frequency cutoff frequency of the detector reaches 2Hz, breaking the technical limitation of imported cables with a low frequency of 3Hz, which can effectively improve the quality of seismic acquisition data.

After completing the operation in the deep-sea area, the independent equipment of "Haijing" has been mature applied and technologically validated in China. After the entire Heshan Depression work area is completed, the "Haijing" system will also plan to enter the international market and carry out international exploration operations.

(CCTV News Client)

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