The idea of using the turbine for drilling appeared in the mid 19^th century, when the Russian citizen Mr. M. Kapeliushnikov had designed a single-staged turbine and a multistage gear reducer. Unfortunately, the industry back-then was not ready for its realization.

Later, the Russians had modified and enhanced the turbo drill by developing the multi-stage turbo drill without a gear reducer. The objective was to have turbine with long - life in the hole in addition to high rotation speed of bits, also at a high axial weight on the bit. Actually, a new drilling technique was created and became the classical type of all modern turbo drills. Therefore, further improvement in the turbine led to the creation of new drilling techniques for both vertical and deviated holes.

The development of directional drilling skills, put forward a demand for a new technique: Alongside with multistage turbo drills for vertical drilling, short powerful down hole motors and turbines were designed for directional drilling. The gear reduction turbo drill was one of them.

A number of Western companies engaged in drilling technique showed significant interest in this achievement. Some leading companies were looking for ways of cooperation with VNIIBT in the field of creation of the gear reduction turbo drill. Thus, a joint engineering of the gear reduction turbo drill was carried on with companies like Neyrfor-Weir Ltd., Drico and others.

The first horizontal well in the world was drilled in Russia during 1937 at Yarego field. Consequently, this technique had gained a wide popularity all over the world. In the last few years many horizontal wells have been drilled around the world.

 In the 1980s the majority of directional drilling workload was performed by using turbine technique. This technique was used in Russia to a large extent in developing West Siberian oil deposits. Directional drilling represents 90% of the total drilling activities. This percentage illustrates the significance of this technology.

The implementation of advanced down hole drilling tools led to develop the new methods of drilling deviated, horizontal, drain, large  and super deep holes. The deepest well in the world; Kolsky (40,121 ft); was drilled by a turbine equipped with a gear reduction turbodrill.

The Egyptian Borais Petroleum Investment Co. was cooperated with Russian VNIIBT Co. in join application of turbodrills and gear reducers as well as other drilling tools. Teamwork was established in the framework of joint scientific and research activities, design and innovation of drilling technique. A New Steerable Turbine has been developed as results of this cooperation.

Specifications and performance chart are enclosed.

The concept of the new turbine is similar to the one used to drill the world deepest wells. Thus a gear reduction 7 1/2" turbodrill was used to drill the Kola super deep well (41,121 ft). The drilling operation was in igneous rock (granite and gneiss) at the temperature 314 deg. F. Information on this well is enclosed.

The Previous experience and information collected during the process phases of engineering and operations of turbodrills were accomplished in a new and effective design of a hydraulic down-hole tool “TRM-195” with gear reduction.

Gear reduction turbodrill ”TRM-195” is a common down hole tool capable to provide the most beneficial regime of operation for all types of bits in various geological and technical conditions.

TRM-195 gear reduction turbodrill with a gear section PM-195 was successfully applied at SG-3 super deep Kola well from the depth 26610 ft down to 40121 ft. The thermo-resistant version of the gear reduction allowed drilling at bottom hole temperature of 410°F. A new construction of the drilling rig was used. Unique URALMASH-15000 provided for fast trips. The time of the round trips to the depth of 26000 ft. was reduced to hours due to unique automated devices that allowed carrying out several operations simultaneously.

The objectives of drilling the Kola well:

• To test the geological structure’s theory of the Earth.

• Data gathering for formation at deep depths.

• To obtain information on the existing ores at such depths.

• To observe geothermal gradient in crystal massive. (A total of 17433 ft were drilled in the crystal missives).

BORAIS-VNIIBT Turbodrills are modified / improved versions of the Russian steerable turbodrills currently used in Russia for directional drilling operations. The new Steeable Turbine has been developed by Borais as results of the cooperation with the Russian VNIIBT Co.

 The following features of the new versions make them different from conventional turbodrills:

COMPONENTS

Turbodrills have a power generating section, a bearing section (spindle) or a gear reducer spindle and are provided with stabilizers.

TURBINE SECTION

The turbine section is a multi - stage hydraulic turbine of a special profile, which ensures a high torque output, and a pressure line independent of the turbodrill operational regime. The shaft of the turbine section is installed in the strengthened radial bearings.

BEARING SECTION

1. The bearing section (spindle) has a multi-step rubber and metal axial bearing with elastic bearing surfaces manufactured on the level of an embracing steel casing. The lower radial bearing of the spindle has an enlarged axial length to provide effective operation at large cross loads.

2. The gear-reducer spindle includes the unit of the input shaft, the planetary gear and the unit of the output shaft with rolling bearing. All unites are places in a common oil-filled chamber.

Axial bearings of an input and output shafts represent roller thrust bearings of a high load-carrying capacity manufactured from special bearing steel.

A planetary gear has a catching with a plane contact to provide for a load - carrying capacity which can't be achieved in other types of gears of the same size. At the gear ratio 3.05 the gear reducer reduces rotational speed by more than 3 times increasing equally the torque on the bit. The upper and lower sealing protected from shaft vibration seal the oil-filled chamber. To balance the pressure in the oil-filled chamber with that in the mud chamber there is a compensatory of a piston type. Excess pressure from oil on the upper sealing is created with a special inner pump. To carry radial weight on the bit the output shaft is provided with an additional radial bearing made of hard alloy. The plate sealing "mud-to-mud" prevents leakage of mud into a clearance between pipes.

The connection of the power and bearing sections set on the bent housing. The shafts are connected using a special torsion bar which performs the function of a universal joint.

CENTRALIZING DEVICE

Centralizing device is installed on the upper bent housing of the turbine section and on the pin of the spindle and gear reducer pin. Stabilizer is placed on spindle shaft and the gear reducer shaft.

OPERATIONAL RECOMMENDATIONS

1. The acceptable aniline point should not be lower than 71 °C in case of turbo drilling with oil based mud. Maximum temperature of circulating mud in the turbodrill should not be more than 120 °C. (248 °F), Static bottom hole temperature 150 °C. (302 °F). Abrasive Solid Contents should not exceed 1 %.

2. The mud flow rate should not be more than 800 GPM in case of turbo drilling with the spindle. Mud flow rate range of 560 – 700 GPM is required when working with a gear reducer spindle

3. The turbodrill should be checked at the operational mud flow rate at rotary table before running in hole. The turbodrill should be started smoothly at the pressure not exceeding 500 psi.

Be sure that the pumps are “ON” before tagging the bottom. The proper RPM along with weight on bit should be selected. The drilling scheme should be changed if high vibration of the tool occurs. Before POOH, the tool should be cleaned from inside.

Post POOH with the turbodrill it is necessary to check out the following:

1.  If the shaft is rotating easily by turning it through by the chain wrench with the torque 200-400 N.m. (150-300 ft Ibs). The shaft of the gear reduction spindle should be rotated only clockwise.

2. Check the axial clearance and the radial clearance of the shaft. The radial clearance should not exceed 2 millimeters, the axial clearance of the spindle should not exceed 5 mm and the axial play of the gear reduction spindle should not exceed 0.5 - 1 mm.

When recommended operating parameters, items 1-3, are exceeding the acceptable range and 200 operating hours of the turbo drill, the turbodrill should be sent to the maintenance base after washing same with fresh water then filling it with minimum of 2 gallons of oil.