Continuous circulation drilling system is the key technology to realize continuous circulation drilling technology, which integrates mechanical, electrical, hydraulic and control technologies. It mainly uses the opening and closing of the ram of the main engine room assembly to form and control the communication and isolation between the upper and lower sealed rooms of the main engine, and cooperates with the shunt manifold to complete the shunt switching of drilling fluid channels in the closed room, thus realizing the uninterrupted circulation of drilling fluid in a single pipe. Using the coordinated action of the power tong, the balance compensation device and the cavity back tong, the automatic make-up and make-down operation of the drill pipe in the sealed cavity is realized.
3. 1. 1 Research status at home and abroad
In 1995, Laurie Ayling first put forward the concept of continuous circulation drilling (CCD), that is, to maintain the continuous circulation of drilling fluid during the connection process, and applied for the first patent; In 1999, Dutch Shell NAM Company concluded through quantitative risk analysis that continuous drilling fluid circulation will reduce the non-operational drilling time by half and save the operating cost 1 10,000 USD per well. In 2000, the continuous circulation drilling joint industrial project began to run, which was managed by Maris Company and supported by ITF and "Industrial Technology Joint Organization" composed of Shell, BP, Total, Statoil, BG and ENI. 200 1, Varco Shaffer was selected as the equipment manufacturer and supplier to participate in the development. In 2003, BP successfully tested a continuous circulation system prototype in an onshore oil well in Oklahoma, USA, and then started the design and manufacture of the engineering prototype. In 2005, ENI successfully realized the commercial application of continuous circulation system in Agri oilfield in southern Italy and PortFouad oilfield along the coast of Egypt. From 2006 to 2008, Statoil used the continuous circulation system to drill 6 wells in Beihai Oilfield, all of which achieved great success. After nearly 10 years of development, foreign continuous circulation systems have entered the stage of popularization and application. After the remarkable success of ENI and Statoil, BP, British Gas and Shell are also considering using this technology for the first time.
In China, PetroChina Drilling Engineering Research Institute has been tracking this technology since 2006, and has begun to study it. After years of technical research, on April 9, 20 12, the basic movement of the continuous circulation drilling system prototype developed by China Petroleum Drilling Engineering Research Institute and Bohai Drilling Technology Service Company was successfully realized. However, there are still many problems in the control accuracy and reliability of the system, and the prototype needs further research on key technologies.
3. 1.2 key technologies
Considering the maturity of technical development and the safety of field operation, the development of continuous circulation system should be based on the characteristics of China's 10,000-meter deep hole drilling technology and develop continuous circulation drilling technology with independent intellectual property rights. Continuous circulation system is an advanced drilling technology and equipment integrating machinery, electricity, liquid and control. To successfully achieve the goal of localization, we must first conduct in-depth analysis and research on the key technologies of the system. The key technologies and difficulties of continuous circulation system mainly include the following aspects.
(1) high-pressure dynamic sealing technology
Under the continuous circulation of high-pressure and high-temperature mud and the movement (axial and rotary) of drill pipe, there will be relative rotation and axial movement between semi-sealed ram and drill pipe in orifice connection system, so the dynamic sealing performance of ram is a key problem. At present, foreign products connect drill pipes under the pressure of 35MPa, and the ram must be replaced every 40 ~ 50 times.
(2) Precise positioning and connection technology of drill pipe.
The joint of drill string and drill pipe is connected and disassembled in a pressure chamber that cannot be directly observed. The position of drill pipe is controlled by the up-and-down movement of top drive, and the position of lower drill string is determined by slips and connectors. How to keep the threaded joint of drill string and drill pipe in a reasonable position and facilitate thread alignment is the key to successfully complete continuous circulation and improve system efficiency.
(3) Protection technology of connecting thread and rod body of drill pipe.
Drill pipe body protection. In the process of screwing in, the drill pipe body is easy to be damaged; In particular, the power slip part should not only bear the weight of the drill string, but also provide enough on-off torque, which makes the stress state between the drill pipe body and the slip tooth plate very complicated, and it is easy to cause the drill pipe to slip and damage the body, and even cause the drill string to slip off the well.
Butting and tightening of drill pipe joints are carried out in a sealed cavity, so the operator can't directly observe the situation in the cavity. At the same time, the high-pressure drilling fluid in the cavity makes the thread of the joint bear great jacking force, and improper operation is easy to cause thread damage. Therefore, when butting and tightening the joint, the jacking force of drilling fluid must be balanced by forcing the tripping device to keep the contact force on the threaded joint surface at an appropriate value. In addition, thread compound must have anti-scour ability to avoid joint thread sticking.
(4) Mud conversion and diversion technology
The key of mud diversion control is to ensure that the circulating pressure is stable and undisturbed. Because of the pressure difference between the riser and the bypass pipeline, direct switching is easy to cause unstable mud circulation pressure, and high-pressure mud will also scour and impact the valve parts. Therefore, before switching, the pipeline on the low pressure side must be pressurized to eliminate the pressure difference between the riser and the bypass pipeline, which can not only keep the mud circulation pressure stable, but also eliminate the adverse effects on the valve and effectively improve the service life of the valve.
3. 1.3 research content and simple scheme
The main equipment to realize the continuous circulation drilling technology is the continuous circulation drilling system, which has complex control and high safety and reliability requirements. In the development process, it is necessary to deeply analyze and study the key technologies such as high-pressure dynamic sealing technology, precise positioning and connection technology of drill pipe, thread connection and protection technology of drill pipe, and mud switching and shunting technology.
Based on the full investigation of the research status at home and abroad, and through the comparative analysis of the structure of typical continuous circulation drilling system, it is determined that the continuous circulation drilling system to be developed in this project is mainly composed of mud connector, shunt manifold device, drill pipe handling manipulator, control system and power system.
(1) research content
The main research contents are as follows: ① Investigation and analysis of technical data of continuous mud circulation at home and abroad; (2) Formulation of continuous mud circulation control flow; (3) Implementation scheme of continuous mud circulation system (including mud connector, shunt manifold device, drill pipe handling manipulator, control system and power system, etc.). ); ④ Simulation analysis of key components; ⑤ Study the overall design and design of each part of the prototype; ⑥ Manufacture and processing of prototype; ⑦ Laboratory and field experimental study of the prototype; ⑧ Research on continuous circulation drilling technology and optimization technology.
The reference design parameters are: working pressure ≤35MPa, outer diameter of drill pipe, maximum torque of 9 kn m, mud flow ≤ 1200gpm(75.7L/s).
(2) Research scheme
Mud joints can be composed of three structures similar to blowout preventers, and each structure has a sealing plate inside, in which the reverse sealing ram is in the lower structure and the blind plate is in the middle. The structures at the top and bottom are provided with bypasses and valves, which are connected with the shunt manifold device and used as channels for pressurizing, depressurizing and maintaining drilling fluid circulation when connecting a single pipe; The drill pipe lifting manipulator has the functions of screwing up, fastening and unscrewing, can move up and down under the drive of the forced lifting device, and is equipped with power slips to bear the hanging weight of the drill string and provide screwing up and unscrewing torque; The control system provides action driving force and driving instructions for each executive part of the system, and the power system is mainly a hydraulic station, which provides driving power source.
Based on the basic structure of triple ram blowout preventer, the research of mud coupling and shunt manifold device can be carried out by technical transformation, increasing mud shunt channels, paying attention to local detail design and selecting new materials. The technical problem of high-pressure dynamic seal is solved, a new pressure-resistant and shock-proof structure is designed, and the disturbance problem of mud diversion switching is solved. The manipulator of drill pipe loading and unloading ensures the accurate positioning, centering and connection of drill pipe and drill string by optimizing control elements and improving control algorithm. By improving the contact conditions and materials of the sliding gear plate, the thread lubrication seal is improved and the damage of the thread and the rod body is reduced. The power system adopts hydraulic drive and modular design, combined with manual and automatic technology, which improves the convenience and reliability of operation. The logical control signals of the control system are mainly pressure and position detection, in which the pressure detection includes seal chamber pressure, riser pressure and working pressure of each actuator, and the position detection refers to the opening and closing of the ram, the opening and closing of the mud valve, the position of the drill pipe joint and the action position of each actuator, etc. Through redundant design, the accuracy and reliability of logic control signals are ensured.
3. 1.4 research plan
The research of this project strives for the support from all sides, especially the national or industrial scientific research projects. It is planned to complete domestic and international information research and analysis, overall technical implementation plan, key technologies and technical difficulties, prototype processing, manufacturing and assembly, field experiments and continuous circulation drilling technology optimization with independent intellectual property rights in China in five years to meet the requirements of field pilot use.
From June 20 13 to June 20 13, the information investigation and comparative analysis of continuous circulation drilling system at home and abroad were completed, and the basic ideas for the development of continuous circulation system were put forward.
From July, 20 13 to June, 20 13, 12, the formulation of continuous circulation drilling control flow and the preliminary design of the overall scheme of continuous circulation drilling system were completed, and the preliminary research of some key subsystem design schemes was completed;
Detailed design scheme of continuous circulation drilling system, detailed design scheme (first draft) of each part (mud joint, shunt manifold device, drill pipe loading and unloading manipulator, control system and power system), key and difficult problems (high pressure dynamic sealing technology) were completed from October to February.
From June, 20 15 to June, 20 15, the simulation analysis and research of key parts of the continuous circulation drilling system were completed, the overall design scheme (implementation draft) of the continuous circulation drilling system was completed, the design schemes (implementation draft) of each part were completed, and the drawings and calculations (implementation draft) related to the overall scheme and local scheme were completed and passed;
From June, 20 15 to June, 20 15, 12 carried out the prototype processing of continuous circulation drilling system, completed the indoor experimental scheme design of continuous circulation system, and completed the field experimental scheme design of continuous circulation system.
From June, 2065438+October, 2006/KLOC-0 to June, 2065438+February, 2006, indoor and field tests of continuous circulation drilling technology were completed, problems were summarized, new optimization and solutions were put forward, and the research of continuous circulation drilling technology was completed.
2017 ~1~ 2017 ~12 was rectified according to the optimized scheme, and combined with many tests, the research goal was achieved and a summary report was written.