Recently, the "Large-Diameter All-Electric Precision Managed Pressure Drilling System" independently developed by China Petroleum Sichuan Drilling Engineering Co., Ltd. (hereinafter referred to as Sichuan Drilling Company) has been successfully selected as one of the first batch of major technological equipment in the energy sector under the fifth national initiative. After evaluation by academicians and expert panels, the system fills the industry gap in managed pressure drilling technology for wellbores with diameters of 311.2mm and above, equipping China with the capability for 10,000-meter-class deep-well managed pressure drilling operations internationally, thereby safeguarding the exploration and development of ultra-deep oil and gas resources in China.

What are the challenges in developing equipment for ultra-deep drilling?

As global oil and gas resource development moves towards deeper and ultra-deep layers exceeding 10,000 meters, multi-string wellbore structures result in increasingly larger upper wellbore diameters. These wells feature long open-hole sections, coexistence of multiple pressure systems, high drilling fluid discharge volumes, substantial cuttings production, narrow safety margins, and even zero or negative safety windows. Conventional drilling often leads to frequent overflow and loss complications, extreme well control risks, and difficulties in reaching geological targets.

China's ultra-deep oil and gas resources account for 70.3% of the total. With the continuous advancement of national deep-earth strategies, ultra-deep wells have surpassed 10,000 meters in depth, featuring even larger upper wellbore diameters and higher discharge rates. These conditions impose greater demands on existing precision managed pressure drilling systems in terms of wellhead pressure control accuracy, operational capacity, equipment erosion resistance, lifespan, and other aspects:

First, significant self-adaptive flow effects are evident. Large-diameter vertical well sections require drilling fluid discharge rates of 70-100 liters per second. The viscosity, density, and rheology of drilling fluids affect their flow characteristics, especially under high-pressure conditions where fluid velocity and pressure changes become more pronounced. Solid particles (e.g., cuttings) carried by the fluid may block channels, further exacerbating flow effects. Second, severe pipeline erosion occurs. High discharge rates and sand content in large-diameter vertical sections lead to severe erosion of choke valves, seats, and pipe bends. Third, large-diameter rotary steering tools suffer severe wear. Under high-speed conditions, the relative linear velocity between rotating components and contact surfaces increases, causing friction heat buildup and accelerated material wear, reducing tool performance and potentially causing equipment failures. Fourth, wellhead pressure control is highly challenging. The core objective of managed pressure drilling is precise control of annular pressure within safe margins. Variations in flow rates and equipment dimensions increase the difficulty of rapid, accurate pressure adjustments.

As the first in the energy sector, where does the system's innovation lie?

To address deep-earth drilling challenges, Sichuan Drilling Company, in collaboration with CNPC Engineering Technology Research Institute, Southwest Petroleum University, and other domestic and international partners, has developed the world's first large-diameter all-electric precision managed pressure drilling system, CQMPD-Max, based on their proprietary "Full-Process Precision Managed Pressure Drilling Completion Technology and Equipment." Compared to domestic and international counterparts, the system features three major innovations:

First, it solves the challenges of ultra-high-speed stable operation and high-pressure sealing in large-diameter rotary steering tools. The invention includes a self-compensating rotary steering tool sealing structure and a rotary diverter pressure-bearing structure, resulting in a 680mm large-diameter electric rotary diverter. The system adapts to wellbore diameters expanding from 241.3mm to 593.7mm, with a pressure-bearing capacity of 35MPa under large-diameter abrasive conditions and a rotation speed of 120rpm.

Second, it overcomes high-pressure, high-disturbance flow control challenges under high discharge rates. The development includes a wide-linearity spool-type choke valve with non-step speed-adjustable actuators based on the relationship between pipe diameter, excitation frequency, response intensity, and measurement signal characteristics under high discharge conditions. Adaptive signal processing methods for crosstalk and autocorrelation/intercorrelation are established, enabling precise, rapid pressure adjustments under ultra-high discharge rates. The flow system's full diameter increases from 80mm to 130mm, accommodating 120 liters per second ultra-high discharge flow control with 263% efficiency improvement.

Finally, an algorithm combining "choke valve characteristic curves + PID + valve position step response" is developed. The system features annular pressure correction and target bottom-hole equivalent circulating density automatic tracking algorithms. By optimizing choke characteristics, reducing pipeline self-adaptive flow effects, and improving erosion resistance, the all-electric precision managed pressure drilling system's pipeline design is enhanced. Control accuracy improves from ±0.2MPa to ±0.07MPa, with a remote-local integrated control platform enabling expert remote monitoring and local collaborative high-efficiency control.

What is the market positioning and future application potential?

The "Large-Diameter All-Electric Precision Managed Pressure Drilling System" offers high control accuracy and long service life, rated at Technology Readiness Level 8. It is suitable for complex geological conditions such as ultra-deep wells, (ultra) deep wells, and horizontal wells. Through high-precision pressure control, improved self-adaptive flow effects, and real-time bottom-hole pressure monitoring and adjustment, it prevents overflow incidents. As conventional oil resources deplete, demand for 10,000-meter-class complex wells like ultra-deep and (ultra) deep wells continues to grow. With drilling technology advancing towards intelligent and automated solutions, the system is projected to meet annual demand exceeding 100 wells, offering broad market prospects and significant economic benefits.

Additionally, the system breaks foreign monopolies on high-end technology, with 100% domestic production of core components. It drives domestic industries like mass flow meters, choke valves, and sealing rubbers towards high-end development. The project has generated 21 invention patents and 10 software copyrights, comprehensively protecting core technologies while enhancing industrial value chains and elevating China's "intelligent manufacturing" capabilities.

Li Zhilin, head of Sichuan Drilling Company's precision managed pressure drilling technology innovation team, stated that large-diameter wellbore pressure control equipment remains a gap in foreign companies. This system not only fills the industry's (ultra) large-diameter wellbore pressure control void but also facilitates safe, efficient exploration and development of 10,000-meter-class deep wells.

Currently, the joint project team has established a full industrial chain covering "R&D-manufacturing-maintenance-service" for this system. It demonstrates excellent adaptability in deep and ultra-deep wells across Sichuan-Chongqing, Tarim, Bohai Bay, and Turkmenistan regions. Next, the system will expand to complex blocks in Central Asia, the Middle East, and Russia, securing high ground in 10,000-meter-class safe drilling technology. This will continuously enhance China's core drilling competitiveness, capture international high-end markets, and strengthen industry discourse power.