This device was applied to the Western Bazhou well 90001 team and tested under single drawworks (DW), double drawworks, tripping and other working conditions. Through testing data and analyzing waveform, within the scope of protection, when the latches were not inserted in place, the electric drive system could quickly and effectively limit torque output of the drawworks, preventing the occurrence of single lifting ring accidents.
4.1. Test under working conditions of single and double drawworks
Tested single machine DWA, single machine DWB and dual machine DWAB to ensure that the single lifting ring protection can be activated timely and effectively under these three working conditions. Fig. 10 shows the HMI display that simulated the single lifting ring accident when DWAB were running.
The empty traveling block was 27.7 tons as shown in Fig. 10a, and the torque of DWA and DWB was limited to 550Nm. The hook height was at 0m. When the traveling block was up lifting and the left latch was not inserted in place, the single lifting ring protection inputted, and the torque limit was triggered. When the tonnage rose to 31.1 tons (Fig. 10b), the traveling block could not up lift, the increase of lifting pull was controlled at about 3 tons.
The Fig.11 shows the case when only DWA was running. The empty traveling block was 27.1 tons (Fig. 11a), the torque of DWA was limited to 1100Nm. Simulated the occurrence of the single lifting ring accident within the scope of protection, when the tonnage rose to 30.9 tons (Fig. 11b), the traveling block could not up lift, the increase of lifting pull was controlled at about 4 tons.
The Fig.12 shows the case when only DWB was running. The empty traveling block was 26.2 tons (Fig. 12a), the torque of DWB was limited to 1100Nm. Within the scope of protection, the traveling block with drilling tools was up lifting, the left latch was not inserted in place, when the tonnage rose to 29.9 tons (Fig. 12b), the traveling block could not up lift, the increase of lifting pull was controlled at about 4 tons.
The data that the rig 90001 team tested at the site is shown in the table 1. From the test data, it can be concluded that whether single or double drawworks are running, the single lifting ring protection can be effectively invested, and the increase of lifting pull can be controlled within 5 tons.
Working Condition and Limit Value
|
Test Data
|
Drawworks Assignment
|
Torque Limit (Nm)
|
Hook Load ( the Empty Traveling Block) (T)
|
Hook load (T)
|
∆T (T)
|
DWA+DWB
|
DWA
|
550
|
27.7
|
31.1
|
3.4
|
DWB
|
550
|
27.5
|
31.1
|
3.6
|
DWA
|
DWA
|
1100
|
27.1
|
30.9
|
3.8
|
DWB
|
---
|
---
|
---
|
---
|
DWB
|
DWA
|
---
|
---
|
---
|
---
|
DWB
|
1100
|
26.2
|
29.9
|
3.7
|
Table 1. Test data from simulations of single lifting ring accidents under the above three working conditions.
4.2. Test under working conditions of tripping.
Tested the normal lifting of the drawworks and the occurrence of the single lifting ring under tripping working conditions. Fig. 13 shows the torque waveform during normal operation of the traveling block. There was no operation at 0 to 900ms, and the torque value was about 900Nm, at 900ms, began to give speed to the drawworks , the drawworks sped up to up lift, the torque rose sharply, and the traveling block went up normally, output torque reached a maximum of 2600Nm at 1300ms and the torque began to decrease before the speed reached its maximum, at 1800 to 2200ms, the speed was roughly stable, the torque was also fluctuating slightly around 1100Nm, at this time the traveling block gravity and the drawworks output reached a balanced state. Therefore, in order to lift the empty traveling block within the scope of protection but not lift any drilling tools, the torque of the single lifting ring protection can be limited to 1100 Nm.
The Fig. 14 shows the case of the traveling block with 11 drill collars weighed about 43.3 tons, which was up lifting normally. At 3650ms, the maximum output torque of the drawworks in the acceleration stage was 3600Nm, When the load gravity and the drawworks pull force were balanced, the speed was roughly constant, and the torque was stable at about 1900 Nm.
The Fig. 15 shows the waveform from simulations of the single lifting ring when the traveling block with drilling tools was up lifting, at 0 to 4000ms, the elevator was placed on the drill floor, the load was an empty traveling block, and the torque at this time was 900Nm, at about 4000ms, began to give the speed, the drawworks carried the traveling block and drill collars weighed about 25.4 tons to up lift, the torque increased instantaneously, at this time one side latch was not inserted in place, and the torque was limited to 1100 Nm. After 7200ms, wire ropes were tightened, the traveling block could not be up lift, the torque was greatly reduced, and finally maintained at 900Nm. Then tested another case, removed a drill collar, reduced the load weight to 23.3 tons, once again lifted the drawworks, one side latch was still not inserted correctly, the protection control was still not relieved, and the torque was limited to 1100Nm. Later removed more drill collars, it can be seen from Fig. 14 that the output torque of the drawworks was still limited when the single lifting ring accidents happened
From the field test, it can be concluded that when one or both side latches have not been inserted in place, the torque output is limited, and the drawworks output cannot drag drilling tools to up lift, effectively preventing single lifting ring accidents, ensuring personal safety and avoiding economic losses, the device is also simple to operate and highly reliable.