WELL CASING AND COUPLINGS FOR IT

The well casing is used during construction and operation of oil and gas wells. The well casing is interconnected by means of coupling threaded connections of OTTM, OTTG, BUTTRESS types and premium threads of TPH-VG type.

The threaded pipe connections ensure: construction of complex-profile wells, including those in deviation intervals; sufficient strength for all load types and necessary leak-proofness of pipe string connections; the pipes are manufactures according to GOST 632-80, API Spec 5CT, and taking into consideration special requirements of the customer. The well casing is supplied with protection of threaded pipe and coupling connections by means of corrosion preventing grease and threaded protective elements.

DESCRIPTION OF DESIGN OF BTS TYPE WELL CASING
DESCRIPTION OF DESIGN OF BTS TYPE WELL CASINGThe coupling connection of BTS (buttress) well casing with buttress profile thread is used for construction and operation of vertical oil, gas and gas condensate wells. A peculiarity of BTS type thread pipe connection is the leak-proofness and high resistivity of the threaded connection to tensile loads. The BTS thread profile is non-isosceles trapezium shape with 5.08 mm pitch and 1:16 taper rate. The compression embedded side taking up the load during insertion of the pipe into the coupling at 10 deg. angle to ensure easy installation of the pipe into the coupling and decrease the possibility of the thread jamming. The supporting part of the profile taking up the tensile load is located at 3 degrees to decrease the possibility of disengagement of the pipe thread with the coupling thread at significant tensile and deviation values. The BTS type connection leak-proofness is ensured by high precision of conical threaded parts of the coupling and nipple, filling the gaps in the threaded connection with special thread-sealing grease.
DESCRIPTION OF DESIGN OF OTTG TYPE WELL CASING
DESCRIPTION OF DESIGN OF OTTG TYPE WELL CASINGThe enhanced leak-proof coupling connection of OTTG well casing with buttress profile thread is used for construction and operation of vertical and inclined oil, gas and gas condensate wells. A peculiarity of OTTG type thread pipe connection is the enhanced leak-proofness and high resistivity of the threaded connection to tensile loads. The OTTG connection thread profile is non-isosceles trapezium shape with 5.08 mm pitch and 1:16 taper rate. The compression embedded side taking up the load during insertion of the pipe into the coupling at 10 deg. angle to ensure easy installation of the pipe into the coupling and decrease the possibility of the thread jamming. The supporting part of the profile taking up the tensile load is located at 3 degrees to decrease the possibility of disengagement of the pipe thread with the coupling thread at significant tensile and deviation values. Gas leak-proofness of the connection is ensured by special conical surfaces which are inter-mated with tightness. The sealing conical assembly is located behind the threaded part of the connection at the end of the lesser threaded cone diameter. The precise fixation of pre-load in the connection is performed by contacting the nipple and coupling parts on the inner thrust faces.
DESCRIPTION OF DESIGN OF TPH-VG1 TYPE WELL CASING
DESCRIPTION OF DESIGN OF TPH-VG1 TYPE WELL CASINGThe enhanced leak-proof coupling connection of TPH-VG1 well casing with buttress profile thread is used for construction and operation of vertical and inclined oil, gas and gas condensate wells. A peculiarity of TPH-VG1 type pipe connection is the enhanced gas leak-proofness and high resistivity of the threaded connection to tensile loads. The TPH-VG1 connection thread profile is non-isosceles trapezium shape with 5.08 mm pitch and 1:16 taper rate. The compression embedded side taking up the load during insertion of the pipe into the coupling at 10 deg. angle to ensure easy installation of the pipe into the coupling and decrease the possibility of the thread jamming. The supporting part of the profile taking up the tensile load is located at 3 degrees to decrease the possibility of disengagement of the pipe thread with the coupling thread at significant tensile and deviation values. The TPH-VG1 connection leak-proofness is ensured by two pairs of special conical inter-mated pre-loaded radial and end faces. The sealing conical surfaces are located behind the threaded part of the connection at the end of the lesser threaded cone diameter. The radial comical seal has a system of labyrinth seal grooves and a hydraulic seal chamber. The precise fixation of pre-load in the connection is performed by contacting the nipple and coupling parts along the inner conical sealing and thrust faces.
DESCRIPTION OF DESIGN OF TPH-VG2 TYPE WELL CASING
DESCRIPTION OF DESIGN OF TPH-VG2 TYPE WELL CASINGThe high leak-proof and high-strength coupling connection of TPH-VG2 well casing with buttress profile thread is used for construction and operation of vertical and inclined oil, gas and gas condensate wells. The TPH-VG2 type casing connection design ensured enhanced gas leak-proofness and high resistivity of threaded connection to tensile and bending loads. The TPH-VG2 connection thread profile is non-isosceles trapezium shape with 5.08 mm pitch and 1:16 taper rate. The coupling and nipple thread profiles are mated along the inner thread diameter. The compression embedded side taking up the load during insertion of the pipe into the coupling at 24 deg. angle to ensure easy installation of the pipe into the coupling and decrease the possibility of the thread jamming. The supporting part of the profile taking up the tensile load is located at minus 4 degrees to eliminate the possibility of disengagement of the pipe thread with the coupling thread at significant tensile and deviation values. The connection leak-proofness is ensured by two pairs of conical inter-mated pre-loaded radial and end faces. The sealing conical surfaces are located behind the threaded part of the connection at the end of the lesser threaded cone diameter. The radial conical seal has a system of labyrinth seal grooves on the nipple part and the hydraulic seal chamber on the coupling part to enhance the efficiency of the seal. The grooves are filled with the sealing grease. The precise fixation of pre-load in the connection is performed by contacting the nipple and coupling parts along the inner conical sealing and thrust faces.
SPECIFICATIONS OF WELL CASING
Rated size of the pipe, mm Pipe Coupling
Outer Thickness Inner Weight1 m, kg Outer diameter Length Weight, kg
diameter D of the wall diameter d Do Dw
  1. m
Do Dw
114 114.3 6.4
7.4
8.6
10.2
101.5
90.5
97.1
93.9
16.9
19.4
22.3
26.7
127.0
(133.0)
123.8 170 4.0
(5.6)
3.0
127 127.0 6.4
7.5
9.2
10.7
114.2
112.0
108.6
105.6
19.1
22.1
26.7
30.7
141.3
(146.0)
136.5 174 4.8
(6.6)
3.3
140 139.7 6.2
7.0
7.7
9.2
10.5
127.3
125.7
124.3
121.3
118.7
20.4
22.9
25.1
29.5
33.6
153.7
(159.0)
149.2 182 5.3
(7.3)
4.1
146 146.1 57.0
7.7
8.5
9.5
10.7
133.1
132.1
130.7
129.1
127.1
124.7
22.3
24.0
26.2
28.8
32.0
35.7
166 156 182 7.9 4.4
168 168.3 7.3
8.0
8.9
10.6
12.1
153.7
152.3
150.5
147.1
144.1
29.0
31.6
35.1
41.2
46.5
187.7 177.8 190 9.5 4.8
178 177.8 6.9
8.1
9.2
10.4
11.5
12.7
13.7
15.0
161.0
161.6
159.4
157.0
151.8
152.1
150.4
147.8
29.1
33.7
38.2
42.8
47.2
51.5
55.5
60.8
194.5
(198.0)
187.3 198 8.6
(10.5)
5.3
194 193.7 7.6
8.3
9.5
10.9
12.7
15.1
178.5
177.1
174.7
171.9
168.3
163.5
35.0
38.1
43.3
49.2
55.7
66.5
215.9 206.4 206 13.4 8.0
219 219.1 7.7
8.9
10.2
11.4
12.7
14.2
203.7
201.3
198.7
196.3
193.7
190.7
40.2
46.3
52.3
58.5
64.6
71.5
214.5 231.8 218.0 18.0 9.6
245 244.5 7.9
8.9
10.0
11.1
12.0
13.8
15.9
228.7
226.7
224.5
222.3
220.5
216.9
212.7
46.2
51.9
58.0
63.6
68.7
78.7
89.5
269.9 257.2 218 19.9 10.7