Some Issues About Heavy-Weight Drill Pipe

Why choose heavy-weight drill pipe?

Heavy-weight drill pipe is made from AISI 4145H steel, after all the heat treatment of materials, all physical properties comply with recent provisions of API specification 7. Integral heavy weight drill pipe is a common transition between the drill pipe and drill collars of the drill, which can effectively alleviate the drill collars and transition in the combined stress concentration provides drilling, and can effectively reduce the drill and the wear rate of the connection area and diameter of the borehole. Drill pipe in central part of the thickened, welding joints and thickened in the middle part of the appearance of cemented carbide wear, can effectively protect the pipe from wear and tear. In a soft case of geological formations, heavy weight drill pipe can replace the drill collar to solve a series of problems occurred in vertical drilling.

Most commonly, heavy-weight drill pipe is used as a transition between the normal drill pipe and the heavier drill collars. Standard pipe can’t bear drill collars of vibration and intense pressure at the bottom, so heavy-weight drill pipe in this part of the drill string to withstand harsh conditions. Heavy-weight drill pipe looks very similar to the normal drill pipe, but it's processing in the form of more delicate than the drill collar has more flexibility at the same time.

In some applications, heavy-weight drill pipe may also be used in place of the drill collars。It is used most commonly in directional drilling. Because it bends easily, it simplifies directional control and minimizes connection fatigue problems common to high-angle or horizontal drilling.

The characteristics and advantages of heavy-weight drill pipe

• Extra length of tool joints provides plenty of sace to operate while reducingwear rate and extending the service life of the outer diameter.
• In order to extend the service life of the connection, API Bore Back Box adopts the larger size, whose function is four times as large as the other entire box.
• The entire centre upset protects the tube from outer diamete wear by keeping the tube away from the hole wall, while at the same time reducing the risk of differential sticking.
• HWDP with the drill pipe elevator can quickly and effectively deal with the task of drilling platform.
• Research shows that 95% of the cause for drill string failure can be attributed to fatigue failure. However, the structure of HWDP has high fatigue strength.

 

The use of heavy-weight drill pipe

Used for straight well

Between the drill collar and ordinary drill pipe connection 15~30 roots weighted drill pipe can prevent the drill pipe from fatigue damage.

Used for directional well

After directional well drilling column connected to the heavy weight drill pipe, the drill collar and heavy-weight drill pipe is not close to the wall, so as to reduce the possibility of mud cake sticking and breakout torque is reduced. Meanwhile the drill in provided tension will not exceed the well too much weight. In addition, it is better to control the angle and azimuth angle of the well and reduce the number of directional work, so as to shorten the construction period of directional well.

 

Safety of drill pipe

In the process of drilling, the failure of drill pipe in any part will cause serious consequences, and even the well abandoned. With the continuous depletion of shallow resources, the safety and reliability of drill pipe has become a very prominent problem in the future.

Drill pipe failure is generally manifested as the main body fracture and puncture, failure of drill pipe thread, etc. The reason is generally caused by the following factors: drilling drill pipe in basic mechanics conditions, drilling tool combination and drilling technology, caliper rule, eccentric wear, thread sealing grease, drilling fluid, drill pipe structure and material, formation factor, well within the corrosive medium, the result of the interaction of the above factors lead to drill pipe failure.

In summary, the failure of drill pipe is various, and the failure of drill pipe is the result of the combined action of each factor. In terms of each well, We should according to the drillpipe failure analysis, extract the main influence factors and take corresponding measures.

Composite Drill Pipe, A New Technology Development

Advanced composite drill pipe

The new composite drill pipe (CDP) is made of carbon fiber and epoxy resin. The principles are with high temperature curing the metal core shaft, and then extract the core shaft, the curing of the pipe section to complete the processing. Final preparation involves the addition of standard elastomeric centralizers before the pipe is run in the hole. Both the centralizers and the abrasion resistant coating can be repaired in the field. More serious wear can be in plant maintenance as long as it is not completely destroyed. Mechanical properties of CDP are similar to that of steel but less than half the weight of steel.

Advantages of CDP compared with conventional steel pipe

• CDP demonstrates the economic utility in the oil and gas sector. Because CDP combines light weight (less than ½ the weight of steel) with the performance properties of steel pipe, it will be applied to the ultra deep, deep orientation, resource development and other technical research. Onshore, it will allow existing rigs to drill to greater depths. CDP also has significant potential to embedded cables or optical fibers wires in the field of high speed communication technology (Intelligent Drilling Technology). With the weight of the CDP at 40 to 50 percent of steel, the loads to be transported and the weight that must be supported by drilling platforms are significantly reduced. These reductions can provide very substantial cost savings for deep drilling and deep water drilling activity.
• CDP can easily be customized to meet specific requirements for specific applications.  For example, to increase tension and compression strength, more longitudinal fibers are used.  Similarly, more hoop fibers can be added to increase pressure capability . And an increase in fibers angled at 45 degrees will improve torque capacity.  In this manner, CDP can be designed for a particular application, loading conditions and specifications into the program to get a specific slice of production needs.
• Tool joints made from various metals, including non-magnetic stainless steels, can be furnished as an option. This can facilitate the CDP and non magnetic composite connection. It is beneficial to the requirement of directional drilling tools.

 

Technology used in the manufacture of composite materials

Spray-up

This applied in the mold, to establish the required thickness of the material.The process is faster and cheaper than wet lay-up, but mechanical properties are lower.The process is typically used for large, relatively simple structures such as bathtubs, boat hulls and storage tanks.

Compression moulding

This process can generate a high surface finish of the metal plate, mainly used in the automotive industry.The high investment in heated tooling means that the process is only suitable for medium to high volume production.

Injection moulding

Bulk moulding compound is heated and injected into a heated mould, where it is held under pressure until the resin has cured. The process is used for relatively small components for which a short cycle time can be achieved. The high cost of tooling means that the process is suitable only for medium to high volume production.

Resin transfer moulding

The process is suitable for complex, highly-loaded parts, and is used in a wide range of industries. Tools that reduce the load, and therefore allow for cheaper, larger tools to be used to manufacture large structural ship hulls or wind turbine blades

Filament winding

The process is designed to achieve the required thickness of the fiber, the use of high temperature when necessary. In the process, pre-impregnated fibre tows or slit prepreg can be used, the removal of waste using a resin bath but need high temperature curing stage.

Pultrusion

Combined with the previous model, cured resin obtained uniform extrusion part.The process can be automated and uses low-cost raw materials, making it suitable for high volume applications.

Prepreg

Prepreg (pre-impregnated fibre) consists of fibres, fabrics or mats impregnated with resin. Thermosetting prepregs include hardeners in the resin, and therefore have a limited shelf life and are usually stored under refrigeration. Before use, the prepreg is brought to room temperature to avoid condensation. Prepreg is used where high mechanical properties are required and the high cost of processing can be justified. Examples include aerospace structures, sporting goods and wind turbine blades.

Market outlook

As the oil and gas production environment and conditions become more and more complex, the drilling cost and drilling risk continues to improve, the traditional sense of the drill pipe has been unable to meet the use requirements. A new generation of drill pipe towards high strength, high toughness, intelligent, digital, corrosion, safety and environmental protection direction. Thus it causes oil drill pipe manufacturers and materials manufacturers more concerned about the super high strength drill pipe,whose purpose is the adaptability of the improvement of drilling pipe. With the continuous improvement of manufacturing process and improvement, the price of the product is constantly improved, and the new generation of drill pipe will be further development and wide application, which provide strong support for oil and gas exploration and development.

What Is A Drill Collar?

Drill Collar Definition

A drill collar is a device used at the lowest part of a drill string, an important part of the bottom hole assembly (BHA). It is always a very thick-walled tube to apply weight to the drill bit. Normally, a drill collar is threaded at both ends, male on one and female on the other. Except for thickness as a special characteristic, a drill collar owns other unique features, gravity, rigidity, etc.

  Drill Collar Classification

Drill collars can be simply put into three categories according to their structure and material, namely the slick drill collar, the spiral grooved drill collar and the non-magnetic drill collar.

• The slick drill collar is normally a smooth thicked-wall tube, with a thickness in the range of 38 to 53, about 4 to 8 times of that of the drill pipes. It is machined into a uniform cylindrical shape and made up of plain alloy steel.
• The spiral grooved drill collar is also machined from plain alloy steel, but it is normally lighter by 4 to 6 percent than the slicker drill collar. This kind of drill collar is widely used nowadays because the special spiral design largely hold back of the possibility of sticking accidents by reducing the area of contact between the wall and the collar.
• The non-magnetic drill collar is manufactured from the non-magnetic alloy steel. As the magnetic measuring instruments can sense the geomagnetic field when measuring the direction of the borehole, the instruments must be kept working in a non-magnetic environment. However, in drilling process, the magnetic rigs always affect the accuracy of the measuring instrument. Therefore, the utilization of a non-magnetic drill collar can ensure a more reliable measuring result.
  

Drill Collars in Drilling Application

• Drill collars play a vital role in drilling process. Due to the structural features, drill collars can provide weight for drilling purpose, which is drill collar’s one and foremost specialty. Gravity works on a number of drill collars to offer enough downward force needed to break rocks with the drill bit.  
• Apart from providing weight on the bit (WOB), drill collars also work as a shock absorber to dampen the vibration and shaking when drilling takes place. In this way, the drilling process can be carried out in a much steadier state.
• Thirdly, the presence of the drill collars allows the pipelines to stay in the tensile state, while guarantees the rigidity of the drill string under great compression. Thus, the drill efficiency and quality are greatly improved.
• In addition to the above applications, drill collars can help to control the direction of the bottom hole assembly, avoiding the problem of hole deviation and enhancing the performance of drilling.
  

Anson Drill Collar

Tianjin Anson international co., ltd is a pioneer manufacturer and supplier in oil and gas products of high quality and at a competitive price. Anson mainly provides products such as tubing, casing, drill pipes, drill collars and so on.

We have drill collars from 5 to 32 feet, with a diameter from 3-1/8”to 11”. Our drill collars are made of AISI4145H premium alloy steel. These drill collars are fully heating quenched, tempered and water cooling measured to withstand high strength and compression. Strict mechanical inspection is applied to drill collars to make sure that all drill collars can meet the requirements of the API m7-1 specification.

We have been making drill collars for years so we are confident that our drill collars will satisfy or even beyond your demands. We are always here ready to offer you the top quality drill collars as well as our professional and all-embracing service.