In order to explore and exploit oil and natural gas deep in the strata, people must use a variety of drilling equipment and tools to drill through hard and complex formations, which is the main task of drilling. In order to meet the needs of the rapid development of China's petroleum industry, it is necessary to drill more wells, drill wells, and drill wells to double the drilling speed. To this end, while fully mobilizing the positive factors of people, we must also provide drilling workers with advanced and well-performing drilling equipment and tools to make full use of modern science and technology to serve oil drilling. Drilling equipment and tools include surface drilling equipment (oil rigs) as well as drill bits, drill strings, and the like.
Composition of Drilling Rig:
The modern oil drilling rig is a large combined unit. Figure shows the basic equipment for rotary drilling. According to the drilling process, well washing, starting and lower drilling tools in the drilling process, a set of drilling rigs must have the following systems and equipment.
(1) Lifting system. Used for starting and lower drilling tools, replacing drill bits, casings, etc.
(2) Rotating system. It is used to drive the drill to rotate, break the rock and deepen the wellbore.
(3) Circulatory system. It is used to circulate drilling fluid to clean the bottom of the well and carry out the broken cuttings to ensure continuous drilling.
(4) Power equipment. Power equipment for driving winches, turntables, drilling pumps, etc., mostly using diesel engines, and some drilling rigs are driven by AC or DC motors.
(5) Transmission system. The main task is to transfer and distribute the energy of the power plant to each working machine.
(6) Control system. In order to direct the coordinated operation of the various systems, various control devices, such as mechanical, hydraulic or electric control devices, equipped with centralized consoles and observation and recording instruments, are also installed in the entire drilling rig.
(7) Base. Including the drill floor, the base of the machine room and the base of the drilling pump.
(8) Auxiliary equipment. Generally, it includes wellhead blowout preventer, air compression equipment, auxiliary power generation equipment, auxiliary lifting equipment, wellhead tools and mobile homes.
In order to start and lower the drill and unload the drill, manual wellhead tools such as tongs, elevators and slips are required.
The tongs consist of several jaws and shank with dental plates that are hinged to each other. The clamp is used to unscrew the connecting thread of various downhole tools that make up the drill string, such as drill pipe and drill collar. The tongs are used inside and outside (one right and one reverse) in pairs, and the cat's head rope is used to turn the buckle.
The elevator is used to suspend, lift and lower the drill string. The inner diameter of the elevator is slightly larger than the outer diameter of the drill pipe, but smaller than the outer diameter of the drill pipe joint. Hold the drill string joint during work to start and drill down.
When the drill string is screwed or unloaded, the drill string located in the well must be temporarily suspended on the turntable. The slips loaded into the carousel are used to catch the drill pipe and suspend the drill string.
With the rapid increase in the number of deep wells, hard formations, and offshore drilling, the workload for start-up and drill-down operations has increased significantly. The use of the above manual wellhead tool for unloading the thread is labor intensive, low in work efficiency, and unsafe, and there is an urgent need for improvement. At present, various forms of power tongs and power slips are widely used in drilling production. It speeded up the drilling and drilling speed, reduced the labor intensity of workers, and laid the foundation for further mechanization and automation of drilling work.
Blowout may occur when the wellhead blowout preventer opens the high-pressure oil and gas layer, causing serious accidents. In order to control the drilling fluid and the injection of oil, gas and water in the well when the blowout occurs, a blowout preventer is usually installed under the drill floor. At present, the rigs produced at home and abroad are equipped with a complete set of more perfect blowout preventer systems. The BOP combination with a pressure rating of 21 to 34 MPa.
Generally, each rig is equipped with 3 to 4 sets of blowout preventers, such as ram blowout preventer, rotary blowout preventer and universal blowout preventer. The ram blowout preventer has three types: single gate, double gate and three gate. The structure of the shutter has three types: blind shutter, orifice shutter and scissors shutter. The core of the orifice ram has a hole in the center. When a blowout occurs during drilling, the annular space between the drill string and the casing can be closed to prevent drilling fluid, oil, gas and water from being blown out in the well. Blowout preventer. The blind ram blowout preventer is also called a fully enclosed blowout preventer, and its core can directly close the wellhead for the case where the wellhead has no drill pipe. The scissors shutter can cut the pipe in the well in case of emergency to ensure the safety of the wellhead. The structural characteristics of the rotary blowout preventer are: the rubber core can rotate with the drill rod while holding the drill pipe, so that the process requirements of the edge spray drill can be satisfied while closing the drill pipe and the casing annular space. . The rubber core of the universal BOP can seal any drill in seconds and gain valuable rescue time.
When the rig is equipped with three types of blowout preventers, such as ram blowout preventer, rotary blowout preventer and universal blowout preventer, they can be used alone or in combination, which can be used for edge-drilling and drilling. Drilling and reverse circulation drilling and other new drilling processes. Most BOPs are equipped with two sets of manual and hydraulic controls for remote control in case of emergency.
Second, the drilling tool must be equipped with a series of underground drilling equipment in addition to a set of underground drilling equipment. These include drill bits, drill strings, downhole power tools, coring tools, and some auxiliary drilling tools (such as accident handling tools) that are lowered into the well during drilling. The downhole drilling tool is referred to as the drilling tool.
The drill string is a general term for all the columns from the drill bit to the ground. The drill string is a hub connecting the ground and the underground, and is an important means and tool for achieving high-quality and fast drilling. As drilling depth continues to increase, drilling technology continues to evolve and performance requirements for drill strings are increasing. At present, a composite drill string composed of one or several kinds of drill tools has been widely used with anti-slanting, anti-shock, anti-sliding and the like. The composite drill string cooperates with different process measures to control the change of the well inclination, improve the working state of the drill bit, reduce the stuck drill accident, and obtain comprehensive benefits in many aspects.
The use of the drill string runs through the entire process of the drilling operation, so the role of the drill string is: (1) the drill bit is lifted; (2) the weight is applied; (3) the power is transmitted; and (4) the drilling fluid is delivered. Drill strings are complex in the downhole and the environment is harsh, which is often a weak link in drilling equipment and tools. Correct selection of drill string and proper use of the drill string have important significance for improving drilling speed and reducing drilling cost.
The drill string consists of a number of different drills. The composition of the system varies with drilling conditions and drilling methods. The basic drills that make up the drill string include drill collars, drill pipes, kelly bars, and mating joints.
The drill collar is also called the weight drill pipe. During drilling, the drill collar is attached to the drill bit and applies pressure to the drill bit with its own weight. The drill collar is characterized by large wall thickness, strength and rigidity, and is not easily bent after being pressed, thereby facilitating drilling of the wellbore.
The drill pipe is connected between the drill collar and the kelly. Both ends of the drill pipe are provided with joints for interconnection. Drilling workers are accustomed to refer to a single drill pipe as a "single root", and when two or three drill pipes are joined together, it is called a "standing root."
The wall thickness of the drill pipe is thinner than the drill collar. When the drill pipe rotates in the well, it wears friction with the well wall and wears continuously. Under the action of tension, pressure and torsion force, there is sometimes a breakage accident. In recent years, welded joint drill pipes and high-strength aluminum alloy drill pipes have been widely used, thereby reducing the gravity of the drill string and reducing the breakage of the drill pipe.
The kelly kelly is connected to the uppermost part of the drill string, and its polygonal section matches the inner hole of the square in the turntable. The kelly can only move up and down after entering the turntable, so when the turntable is rotated, the drill pipe, the drill collar and the drill bit can be driven to rotate. In order to avoid the need for a single rear drill pipe to enter the turntable, the length of the kelly is generally 2 to 3 m longer than the drill pipe.
Matching joints Due to the different types, sizes and buckle types of drills that make up the drill string, they are generally not directly connected to each other. It is necessary to use a joint to join a uniform and harmonious drill string.
In summary, several drills, such as drill collars, drill pipes, kelly bars and mating joints, form the basic drill string. With the development of drilling technology, in addition to the above basic drill string, a series of composite drill strings can be developed to further improve drilling performance. The most widely used is a composite drill string consisting of a basic drill string plus three (righter, damper and jar).
If the anti-slant drill string formed by adding the centralizer is properly designed and used, it can prevent the inclination and make the wellbore rules, ensure the smooth operation of the drill bit, and improve the work index. Practice has proved that these anti-slant measures are effective.
Due to the different nature of the rock fractured by the drill bit and the different drilling objectives and requirements, many different types of drill bits, such as scraper bits, roller cone bits and diamond bits, are used in oil drilling. The most widely used is the roller bit, which is used in medium hard and hard formations as well as in deep wells. The scraper bit has a prominent position in some high-plasticity and soft strata in China. Diamond drill bits work well in very hard formations and deep wells. With the development of drilling technology, the type and structure of drill bits are constantly evolving and improving. After the 1970s, drill bits with synthetic diamond as the cutting element appeared. Years of on-site use have proven that this drill has a good development vision.
The scraper bit is one of the earliest drill bits used in rotary drilling. The drill bit has a simple structure and is easy to manufacture, and each oil field can be designed and manufactured by itself. The squeegee bit is suitable for drilling soft formations (such as mudstone, shale and argillaceous sandstone formations) and can achieve high mechanical penetration rates and drill footage. However, when drilling hard and highly abrasive formations, the blade is difficult to eat, the drill bit wears quickly, the mechanical drilling speed is low, and sometimes the jumping phenomenon occurs, which has a certain influence on the life of the drilling tool and the equipment. Nevertheless, as long as we use it correctly, we can fully utilize the advantages of the blade bit drilling in the soft formation, which is still effective for improving drilling speed and reducing drilling cost.
After the 1970s, China began to develop and use synthetic diamond scraper bits. The geometry of the drill blade is essentially the same as that of a carbide insert drill bit, except that a portion of the cemented carbide block is replaced with a synthetic polycrystalline diamond insert. Since the wear resistance of diamond is higher than that of cemented carbide, it can increase the use time of the drill bit, prolong the life of the drill bit, increase the single drill bit footage, and create many advanced drilling indexes.
The roller bit is the most widely used bit in oil drilling. When the roller bit rotates, it has the effect of impacting, crushing and shearing the broken rock. The contact area between the teeth and the bottom of the well is small, the specific pressure is high, the working torque is small, and the total length of the working edge is large. Thus, the roller bit can be adapted to rock of various properties. The commonly used tri-cone bit is shown in the Figure.
At present, the domestic drill bit factories continue to introduce advanced technology according to the needs of the production site, so that the production of roller cone bits has been greatly improved in terms of variety, quantity and quality. A series of domestic roller cone drill bits has been initially established.
According to the characteristics of the teeth, the tri-cone bit products are divided into two categories: milling bit and insert bit. There are six series of milling bites and two series of inlay bits.