The development of deepwater oil and gas is imperative, and it is also an urgent need to ensure national energy security, safeguard China's maritime rights and interests in the South China Sea, and build a maritime power. Deepwater oil and gas exploration has the characteristics of high risk, high investment, high technology, and high returns (the "four highs"), and safety is the lifeline of deepwater oil and gas exploration. China has achieved significant leaps from shallow water to deep water, from deep water to ultra deep water, and from deep water exploration to deep water development through three stages of tracking learning, cooperative introduction, and independent innovation. After years of continuous technological breakthroughs, a number of key technologies for risk safety assessment and risk prevention and control of deepwater oil and gas extraction have been successively conquered. The risk identification and safety control technology for deep water oil and gas extraction is a strong support for achieving safe, efficient, autonomous, and controllable development of deep water oil and gas in the South China Sea.

1. Main Technical Difficulties in Risk Assessment and Safety Control of Deepwater Oil and Gas Production in the South China Sea

The South China Sea is located at the intersection of three major tectonic plates, with complex geological conditions. Deepwater oil and gas exploration faces four major challenges: marine environment, shallow disasters, deep geology, and gas well exploration. The disaster mechanism is complex, and the operational risk is extremely high. 

The deep-water marine environment is even worse. More than 10 typhoons and extreme waves occur in the South China Sea every year, with internal wave currents and ocean currents superimposed at a velocity of over 5 knots. The overall environmental conditions are extremely harsh. The South China Sea typhoon has a long season, high frequency, high intensity, high danger, and a typhoon avoidance period of 10-15 days; The duration of the monsoon is long, making it difficult to provide material support;  The development of wave currents in the South China Sea is difficult to predict, with a maximum velocity of 2 m/s and enormous power.

Shallow geological hazards are more complex. Deep water shallow well construction faces geological risk challenges such as shallow gas, shallow water flow, and natural gas hydrates ("three shallows"). The shallow soil in deep water is soft, the seabed is unstable, and the wellhead is prone to instability and sinking. The deep seabed structure of the South China Sea is complex, with the development of landforms such as seamounts, hills, troughs, trenches, valleys, and steep slopes. The terrain is undulating greatly, and the seabed is steep, posing serious challenges to the safety of drilling engineering.

Deep geological conditions are more challenging. The South China Sea is a basin dominated by two major factors: deep water and high temperature and pressure, which poses great challenges to drilling operations. The formation fracture pressure is low, and the safety density window is extremely narrow; The formation has a new age, fast sedimentation rate, poor diagenesis, weak pressure bearing capacity, easy well leakage, high risk of well control, and great difficulty in treatment.

Deepwater oil and gas extraction conditions are more stringent. The environment for deep water oil and gas extraction is harsh, and the safety and integrity testing, monitoring technology, and equipment of extraction facilities face enormous challenges. Deepwater oil and gas extraction facilities are constantly in a dynamically changing engineering geological environment, making them more susceptible to damage and interference from various factors. Wellbore leakage is an important problem that troubles the safe development of gas wells, and the phenomenon of wellbore leakage is particularly serious in the middle and later stages of oil and gas field development. Marine structures have been in service in seawater for a long time, and their surface is prone to defects such as cracks and corrosion. There are various types of defects and complex morphologies, which pose many challenges to underwater non-destructive testing technology.

2. Progress in Risk Assessment and Safety Control Technology for Deepwater Oil and Gas Production in the South China Sea

Through the collaborative research of "industry, academia, research and application", a basic theory of risk identification for deep water oil and gas exploration with the characteristics of the South China Sea has been preliminarily formed, and a safety control technology system suitable for deep water exploration in the South China Sea has been explored, effectively supporting the safe and efficient implementation of deep water oil and gas exploration in the South China Sea.

Deep water marine environmental risk assessment and control technology. In response to challenges such as frequent typhoons and internal waves in the South China Sea, we have carried out research on key technologies for typhoon prevention and safety control in deepwater operations, as well as real-time monitoring and safety control of internal waves in the South China Sea. We have developed a deepwater environmental risk assessment and control technology, which provides important advance and reliable means for achieving safe oil and gas extraction in deepwater.

Risk identification and safety control technology for deep and shallow drilling. We have conducted research on the identification and safety control technology of geological hazards in deep water and shallow layers, the installation of surface conduits by jetting method, and the risk analysis of well construction on unstable seabed surfaces. We have developed risk identification and safety control technology for deep water and shallow drilling, solving key problems in shallow drilling design and safety control.

Key technologies for deep water drilling well control and emergency rescue. In response to the challenges of difficult identification and high control risks in deep water well control, research has been conducted on early identification technology for gas influx and overflow in deep water drilling, construction of scenarios for deep water blowout and loss of control, design technology for deep water rescue wells, and localization of deep water emergency sealing devices. A key technology for deep water drilling well control and emergency rescue has been formed, which integrates basic theories, design schemes, and domestically produced equipment.

Safety detection and monitoring technology for deepwater oil and gas extraction facilities. In response to the harsh environment of deepwater oil and gas exploration in the South China Sea, research and development have been carried out on intelligent monitoring methods for stress waves in deepwater oil and gas exploration facilities, diagnostic technologies and intelligent systems for wellbore leakage monitoring, intelligent visual detection systems for AC electromagnetic fields of underwater structural defects, and fatigue and injury detection technologies for key structural components. A new generation of digital and intelligent safety and integrity testing for offshore oil and gas exploration facilities has been developed Monitoring technology and equipment.

3. Risk Assessment and Safety Control Technology Development Suggestions for Deepwater Oil and Gas Production in the South China Sea

We need to continue to carry out scientific and technological breakthroughs, carry out a series of risk assessments and safety control technology breakthroughs for deep water oil and gas extraction, and ensure the safe, efficient, independent, and controllable development of deep water oil and gas in the South China Sea.

Continuously pursuing the intrinsic safety of deepwater oil and gas extraction. The existing technology is still unable to fully meet the development requirements, with frequent accidents and zero experience in complex development well operations. It is urgent to conquer key technologies for drilling and completion in deep water and complex formations, and continue to pursue intrinsic safety.

Promote the localization of deepwater oil and gas exploration equipment and engineering software. There is an urgent need to carry out the localization of key equipment and materials such as deepwater underwater blowout preventers, riser systems, intelligent completion tools, automated and intelligent drilling equipment, and special environmental drilling fluid systems. In addition, there is an urgent need to promote the localization of key core tool equipment and engineering software.

Enhance risk prevention and emergency response capabilities for deepwater oil and gas extraction. Further research is needed on key technologies such as the construction of blowout accident scenarios, risk warning, emergency sealing, and firefighting rescue, in order to form an independent well control emergency safety guarantee technology system for all sea areas, all water depths, and all working conditions, enhance risk prevention and emergency capabilities, and eliminate deepwater safety and environmental accidents.

Promote intelligence to ensure the safety of deep water oil and gas extraction. Intelligent technology is an effective means to control costs, improve oil recovery, and extend the lifespan of deep water oil and gas development. It achieves functions such as downhole monitoring, testing, and control, identifies problems, and formulates measures in advance to achieve the goals of digital intelligent transformation, technology security, and quality and efficiency improvement.

4. Conclusion

Through years of technical research and practice, a risk identification and safety control technology system for deep water oil and gas production in the South China Sea has been preliminarily formed, with the core of risk assessment and control of deep water marine environment, prediction and control of deep water shallow geological disasters, deep water drilling well control and emergency rescue, and safety inspection and monitoring of deep water oil and gas production facilities. In order to achieve safe, efficient, and autonomous oil and gas production in the South China Sea Controllable development provides strong technical support.

With the advancement of exploration in areas such as ultra deep water, deep water high temperature and pressure, deep water, and deep sea, it is necessary to clarify the development direction, continuously tackle and improve the localization of essential safety, key equipment, materials, and engineering software, efficient risk prevention and emergency response capabilities, intelligent diagnosis and early warning technologies, in order to further promote the development and progress of risk assessment and safety control technologies for deep water oil and gas extraction.