Turbine motor

The bowl is suspended from an upper bearing and drive (electric or turbine motor) assembly through a flexible-drive spindle with a loose guide in a controlled damping assembly at the bottom. The unit finds its axis of rotation if it becomes slightly unbalanced due to process load. 

Items Expander Air blower Steam turbine Motor/ generator... 

Instruction Manual, Synchronous Motors, Instruction Manual 1100-INS-60EM. Dresser-Rand, Electric Machinery (EM), Steam Turbine, Motor and Generator Division. 

The prime mover is the unit that first converts an energy source into a mechanical force. Typical prime movers are internal combustion motors, gas turbines, water turbines, steam engines and electrical motors. The discussion will be limited to the prime movers that are most used in modern well drilling and production operations. These are internal combustion motors, gas turbine motors and electric motors. 

The piston plunger pump is the simplest form of a positive displacement pump. These pumps can be powered by a variety of prime movers, internal combustion engines, and electric motors (and in some cases, powered by a gas turbine motor). In such applications, the separate pump unit is connected to the prime mover by a power transmission. 

Turbine Motors 863. Positive Displacement Motor 882. Special Applications 899. 

Air (or Gas) Downhole Motors. Some positive displacement mud motors can be operated on unstable foam. In general, these mud motors must be low-torque, high-rotalional-speed motors. Such motors have found limited use in air and gas drilling operations where directional boreholes are required. Recently a downhole turbine motor has been developed specifically for air and gas drilling operations. This downhole pneumatic turbine motor is a high-torque, low-rotational-speed motor. 

In 1873, an American, C. G. Cross, was issued the first patent related to a downhole turbine motor for rotating the drill bit at the bottom of a drillstring with hydraulic power [78]. This drilling concept was conceived nearly 30 years before rotary drilling was introduced in oil well drilling. Thus the concept of using a downhole motor to rotate or otherwise drive a drill bit at the bottom of a fluid conveying conduit in a deep borehole is not new. 

The downhole turbine motors that are hydraulically operated have some fundamental limitations. One of these is high rotary speed of the motor and drill bit. The high rotary speeds limit the use of downhole turbine motors when drilling with roller rock bits. The high speed of these direct drive motors shortens the life of the roller rock bit. 

In the 1980s in the United States an effort was initiated to develop a downhole turbine motor that was activated by compressed air. This motor was provided with a gear reducer transmission. This downhole pneumatic turbine has been successfully field tested [82]. 

In this section the design and the operational characteristics and procedures of the most frequently used downhole motors will be discussed. These are the downhole turbine motor and the downhole positive displacement motor. 

Figure 4-190. Basic turbine motor design principie. (Courtesy Smith International, Inc.)...

The rotational energy provided by the flowing fluid is used to rotate and provide torque to the drill bit. Figure 4-191 shows the typical complete downhole turbine motor actuated with an incompressible drilling fluid. 

In general, the downhole turbine motor is composed of two sections (1) the turbine motor section and (2) the thrust-bearing and radial support bearing. These sections are shown in Figure 4-191. Sometimes a special section is used at the top of the motor to provide a filter to clean up the drilling mud flow before it enters the motor, or to provide a by-pass valve. 

Figure 4-191. Downhole turbine motor design. (Courtesy Eastman-Christensen Co.)...

Turbine Motor, 6V4-in. Outside Diameter, Circulation Rate 400 gpm. Mud Weight 10 Ib/gal... 

There are of course variations on the downhole turbine motor design, but the basic sections discussed above will be common to all designs. 

Hard to extremely hard competent rock formations can be drilled with turbine motors using diamond or the new polycrystalline diamond bits. 

Unless a measure while drilling instrument is used, there is no way to ascertain whether the turbine motor is operating efficiently since rotation speed and/or torque cannot be measured using normal surface data (i.e., standpipe pressure, weight on bit, etc.). 

Because of the necessity to use many stages in the turbine motor to obtain the needed power to drill, the downhole turbine motor is often quite long. Thus the ability to use these motors for high-angle course corrections can be limited. 

Downhole turbine motors are sensitive to fouling agents in the mud therefore, when running a turbine motor steps must be taken to provide particle-free drilling mud. 

Downhole turbine motors can only be operated with drilling mud. 

Figure 4-192 gives the typical performance characteristics of a turbine motor. The example in this figure is a 6-J-in. outside diameter turbine motor having 212 stages and activated by a 10-lb/gal mud flowrate of 400 gal/min. 

Figure 4-192. Turbine motor, outside diameter, two motor sections,...

A turbine device has the unique characteristic that it will allow circulation independent of what torque or horsepower the motor is producing. In the example where the turbine motor has a 10-lb/gal mud circulating at 400 gal/ min, the pressure drop through the motor is about 1,324 psi. This pressure drop is approximately constant through the entire speed range of the motor. 

If the turbine motor is lifted off the bottom of the borehole and circulation continues, the motor will speed up to the runaway speed of 1,614 rpm. In this situation the motor produces no drilling torque or horsepower. 

As the turbine motor is lowered and weight is placed on the motor and thus the bit, the motor begins to slow its speed and produce torque and horsepower. When sufficient weight has been placed on the turbine motor, the example motor will produce its maximum possible horsepower of 217. This will be at a speed of 807 rpm. The torque produced by the motor at this speed will be 1,412 ft-lb. 

If more weight is added to the turbine motor and the bit, the motor speed and horsepower output will continue to decrease. The torque, however, will continue to increase. 

When sufficient weight has been placed on the turbine motor and bit, the motor will cease to rotate and the motor is described as being stalled. At this condition, the turbine motor produces its maximum possible torque. Even when the motor is stalled, the drilling mud is still circulating and the pressure drop is approximately 1,324 psi. 

The stall torque M, (ft-lb) for any turbine motor can be determined from [86]. -5 T1hT1n,n.7 ,q tanP... 

The maximum turbine motor horsepower is at the optimum speed, N, which is one-half of the runaway speed. This is... 

The pressure drop Ap (psi) through a given turbine motor design is usually obtained empirically. Once this value is known for a circulation flowrate and mud weight, the pressure drop for other circulation flowrates and mud weights can be estimated. 

If the above performance parameters for a turbine motor design are known for a given circulation flowrate and mud weight (denoted as 1), the performance parameters for the new circulation flowrate and mud weight (denoted as 2) can be found by the following relationships ... 

Table 4-110 gives the performance characteristics for various circulation flowrates for the 212-stage, 6f-in. outside diameter turbine motor described briefly in Table 4-109 and shown graphically in Figure 4-192. 

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