Application test of BH casing drilling technology in complex strata of Makeng Iron Mine

BH- 1 14 casing drilling technology is a new drilling achievement developed by Chengdu Institute of Exploration Technology, Chinese Academy of Geological Sciences. In this technology, the outer pipe is used to replace the rope drill pipe to transmit WOB and torque, which drives the casing coring drilling tool in the hole to rotate drilling, and the rope coring, inspection or replacement of the main and auxiliary drill bits at the bottom of the hole are carried out without drilling, which effectively reduces the tripping times, avoids the instability of the hole wall and accidents in the hole caused by frequent tripping in complex strata, and is beneficial to reducing labor intensity, improving the construction environment and promoting safe production. On September 8, 20 12, the casing drilling technology test of BH- 1 14 (hole depth 25.58 ~ 186m) was carried out in ZK950 1 hole in Shiyankeng mining area, which was not only BH-1.

9.5. 1 casing drilling technology development

The concept of casing drilling was put forward in the early 1950s. Cases related to casing drilling appeared in the 1960s and developed rapidly in the 1990s. This technology uses drillable casing drilling tools, selects a special bit to drill to a predetermined well depth, and then uses a small-diameter bit to drill through the special bit to achieve the final hole-forming goal and finally complete the drilling task. At present, the mature casing drilling abroad includes the casing drilling system of Texco Company in Canada. More than 300 wells have been drilled, with the drilling depth exceeding1000m, and the maximum drilling depth is about 2800m. ..

In 2007, Jilin Petroleum Group Company, Drilling Engineering Technology Research Institute, anniversary Petroleum Administration Bureau and Dagang Oilfield Group Company, affiliated to China Petroleum, jointly carried out the research on the national 863 project "Casing Drilling Technology", and successfully developed the "Supporting System of Casing Drilling Tools Driven by Rotary Table Drilling in Shallow Wells". * * * Eight surface boreholes were tested, of which 65,438+0 wells were deeper than 65,438+.

In the early 1990s, Chifeng 1 13 geological team of Inner Mongolia Geological Exploration Bureau proposed and entrusted Sichuan Chengdu Exploration Technology Institute to carry out casing drilling exploration in the complex stratum construction of Baiyinnuo mining area. In recent years, with the implementation of China's deep geological prospecting strategy, the workload of deep hole drilling has been increasing, and more and more complex formations have been encountered, and the demand for casing drilling technology has become stronger and stronger. In order to solve the problems of long construction period, low drilling efficiency, many in-hole accidents and high cost caused by unstable formation collapse in complex formation drilling, Chengdu Institute of Exploration Technology conducted preliminary research and exploration on casing drilling technology, and developed φ 1 14 casing coring drilling tool in 20 12, which can replace drill pipes.

9.5.2 BH- 1 14 casing coring drilling tool

BH- 1 14 casing coring drilling tool is a kind of casing drilling coring drilling tool for geological exploration aiming at complex strata and casing drilling. The drilling tool adopts the principle of two-stage crushing and pore-forming, and is equipped with two-stage crushing tools, namely the main bit and the auxiliary bit. The former conducts guided coring drilling, while the latter undertakes the task of reaming and hole forming.

(1) Main structure and working principle of casing coring drilling tool

1)BH- 1 14 casing coring drilling tool composition (Figure 9.8). The drilling tool is essentially a φ 1.22 mm coring tool, which consists of a main drilling tool (inner pipe drilling tool) and an auxiliary drilling tool (outer pipe drilling tool). The main drilling tool is equivalent to the inner tube assembly of the wireline coring tool, and it is equipped with a main drill bit (φ 94 single-acting double-tube bit), a common single-acting double-tube coring tool and an auxiliary drill bit (φ 122/φ 94 four-piece combined telescopic drill bit), which belongs to the fishing and throwing part: it can be salvaged from the hole to the ground for coring and checking or replacing the drill bit, and it can also be thrown to the bottom of the hole through casing (drill pipe) for coring, which is equivalent to the wireline drilling tool.

Fig. 9.8 BH- 1 14 structural diagram of drilling tools.

2) Actuator of drilling tool. It mainly includes aiming mechanism, fishing mechanism, stretching mechanism, stretching and reporting system, suspension mechanism, torque and pressure transmission mechanism, limiting mechanism and coring mechanism.

3) Working principle-wedge top expansion and convergence principle (Figure 9.9). After the main drilling tool is drilled, the telescopic shaft assembly moves down relative to the drill frame assembly under the hydraulic pressure, and the auxiliary drill bit is opened, so that the main and auxiliary drilling tools can be connected, and the drilling tools are in the drilling state, so that coring drilling can be carried out (the main drill bit conducts pilot drilling and the auxiliary drill bit undertakes reaming); At the beginning of fishing, the total length of the telescopic shaft moves upward relative to the bit frame assembly, so that the auxiliary bit converges and the connection between the main and auxiliary drilling tools is released. The drilling tool is in the lifting state, and the main drilling tool can be salvaged to the ground for coring, inspection or bit replacement.

(2) Characteristics of casing drilling

BH- 1 14 casing drilling adopts φ 1 14 mm casing as rope drill pipe, φ10/4 mm casing coring drilling tool does not drill, drills to a predetermined hole depth, and lifts the inner tube assembly of the drilling tool out of the well, φ/KLOC.

Main features:

1) The drill bits (main bit and auxiliary bit) and coring device used for rock breaking are installed on the salvageable main drilling tool, and the drill bits can be checked or replaced every time coring, which meets the technical requirements of casing drilling without drilling in long intervals.

2) The main drill bit drills holes in advance, and the auxiliary drill bit reams and protects the diameter. Although the two-stage bit breaks the rock, the annular rock-breaking area is large, but it belongs to the step rock-breaking with more free surfaces, and the ROP in the medium-hard stratum is roughly equivalent to that of the wire-line coring drilling tool.

3) The auxiliary bit consists of four combined telescopic bits. The auxiliary drill bit is driven to open by flushing liquid, and the pump pressure at the moment of opening needs to reach a certain peak value, so it is easy to judge the opening situation of the auxiliary drill bit in the hole according to the change of ground pump pressure.

4) The drilling tools meet the relevant drilling standards, and the drill pipe can be used as a special casing or a wireline coring drill pipe.

5) When the drilling tools are transported in place, there must be a certain bare hole space at the bottom of the hole, which is the shortage of drilling tools in complex formations.

Fig. 9.9 BH- 1 14 drilling tool technology principle

(3) Specifications and main technical parameters of drilling tools (Table 9. 16)

Table 9. 16 Specification and main technical parameters of casing coring drilling tool

(4) φ 1 14 casing (drill pipe)

Φ114 casing adopts rope drill pipe structure, as shown in Figure 9. 10, which is used as a rope drill pipe to transmit torque and WOB during drilling and as a channel to transmit flushing fluid. After drilling, it is left in the hole as the isolation hole wall of the technical casing. The outer diameter of the casing body is φ 1 14 mm, the outer diameter of the joint is φ1/6 mm, the inner diameter is φ 103mm, the length is 3.0m, and a small amount of 2.0m, 1.5m,/kloc-is provided. ..

Fig. 9. 10φ 1 14 casing (drill pipe)

Field test situation

From September 2, 2065438 to September 28, 20 12, BH- 1 14 casing drilling was carried out in ZK950 1 hole section in Makeng mining area. Test footage 157.34m, run φ14 casing 18 1.70m, and realize casing isolation protection while drilling.

Fig. 9.11BH-114 casing drilling technology test site

(1) borehole and its stratum

ZK950 1 hole design depth 1000m, dip angle 90, which verifies whether the faults in the East Tianshan Depression are nappe structures. Drilling was carried out on September 8, 20 12, and the geological purpose was achieved on September 25, 20 12, and the final hole depth was 603.28 m.

ZK950 1 hole stratum: 0 ~ 5.35 m, residual soil; 5.35 ~ 25.38m, sandwiched with structural breccia and breccia sandy mudstone; 25.38 ~ 3 1.82 m, diabase and magnetite; 3 1.82 ~ 79.74m, breccia sandy mudstone, breccia mudstone and metamorphic siltstone; 79.74 ~ 534. 10m, structural breccia, spotted slate and breccia argillaceous sandstone; 534.10 ~ 603.28m, porphyritic medium-fine biotite granite.

Design drilling structure: φ 150mm borehole, drill 20 ~ 50 m, and run φ 146 casing; Φ130mm drilled through the upper limestone with a hole depth of about 200m, and the Φ127 casing was run; φ95mm (cable coring) drilling and running φ89 casing; 75mm rope coring drilling to the final hole.

(2) Main drilling equipment and materials

Drilling rig: XY-5 vertical drilling rig of Zhangjiakou Prospecting Machinery Factory;

Drilling rig: 23m drilling rig;

Mud pump: BW250 mud pump;

Rope winch: 7.6mm wire rope is used;

Mud material: 80 1 plugging agent, polyacrylamide and super lubricant.

(3) Supporting appliances

See fig. 9. 12 for supporting instruments, mainly including φ 1 14 gripper, φ 1 14 extractor, φ1/4 rope fishing device and φ/kloc-0.

Fig. 9. 12 kit

(a) Trojan holders; Extractor; (c) fishing gear; Pipe wrench; (e) φ 1 14 casing lifting head

(4) Testing work.

ZK950 1 hole casing drilling started on the morning of September 20 12 12, with a hole depth of 25.28 meters ... After the drilling tools were assembled, when the pump was started on the ground to debug whether the auxiliary bit was tensioned, it was found that the gaps between the four auxiliary bits and the convergent claws were small, and when the telescopic shaft assembly moved downward relative to the bit frame assembly under the hydraulic pressure, the auxiliary bit did not move. After field debugging, measures such as grinding and adjusting the fit clearance of the auxiliary bit, oiling and lubricating were taken to make the flexibility and fit of the auxiliary bit and the convergent claw meet the requirements.

Drill four times in the interval of 25.84 ~ 30.90 meters. Because the drilling tool of the main bit is equipped with 3m, it works before the main bit and the auxiliary bit does not work, so the drilling footage is faster.

When drilling in the interval of 30.90 ~ 40.85 m, the main bit and the auxiliary bit work at the same time, and several abnormal phenomena appear in the hole: ① the drilling tool is not delivered in place; (2) The auxiliary bit is not tensioned; ③ The inner tube can't be lifted; ④ Mismatch of catches; ⑤ The concentricity of the main and auxiliary drilling tools causes eccentric wear of the drill bit frame, resulting in cracks due to large torque.

In view of the problems encountered in drilling assembly and drilling, emergency measures are taken:

1) When drilling shallow holes, the drilling tools are sent to the bottom of the well by the fishing device. Before leaving the factory, check and adjust the clearance of the telescopic assembly, and add oil to lubricate and debug, so that the drilling tool can move freely.

2) The concentricity of the main and auxiliary drilling tools can be properly solved by adjusting the drilling parameters (reducing the rotation speed and increasing WOB) and shortening the lead of the main drilling tools.

9.5.4 Technical Points of Casing Drilling

(1) Main process of casing drilling

Casing drilling technology is basically the same as conventional wireline coring drilling technology, but the difference is that after fishing and coring are completed once, the service bit can be checked or replaced without drilling, and the drill string can be left in the hole for technical casing to ensure the safety in the hole. Therefore, in addition to paying attention to the judgment of drilling tools in place and opening, the operation method of rope coring drilling can be completely adopted.

Casing drilling completes a technological process: tripping in → preparing the leading main drilling tool and reaming auxiliary drilling tool → sending the main drilling tool (equivalent to the rope inner pipe drilling tool) → turning on the hydraulic drilling tool (the water pump pressure gauge rises and the auxiliary bit is turned on) → drilling → salvaging the main drilling tool → coring, and checking or replacing the main and auxiliary bits. The drilling cycle is repeated until the predetermined hole depth.

(2) Casing drilling parameters (Table 9. 17)

Table 9. 17 φ 1 14 Casing Drilling Parameter Table

Note: When the hole body is 65m, the whole hole leaks and no water enters, so the top leakage drilling method is adopted. The water level in the cave is 40 ~ 60 meters deep.

(3) Precautions for casing drilling

1) When drilling for the first time, because the auxiliary bit does not work, only the main bit should control the drilling speed and WOB to avoid well deviation.

2) After the main and auxiliary drillers drill into the working face at the same time, always pay attention to the situation in the hole when sweeping the hole, and gently press and slowly turn the main and auxiliary drillers to work at the same time.

3) When sending drilling tools, pay attention to whether the drill string is lifted from the effective safe distance of the drilling tools, so as to avoid damaging the main and auxiliary drill bits when the inner pipe drilling tools are sent to the bottom.

4) When the main and auxiliary drilling tools cannot be sent to the bottom hole at one time, the situation in the hole should be judged and the reasons analyzed. Don't forcibly pull the inner pipe, so as not to break the wire rope of the fishing device, resulting in drilling lifting.

5) In the process of drilling, if the matrix hardness of the main and auxiliary bit is not suitable for the formation, it should be lifted immediately for inspection, analysis and adjustment, and it is not allowed to be lazy.

6) The length of the main drilling tool can be adjusted according to the formation conditions. If the formation is complete, the length of the main drilling tool can be appropriately extended, and the length of the main drilling tool should be appropriately adjusted and shortened in complex, broken and uneven soft and hard formations.

7) Casing drilling coring is basically the same as wireline drilling coring. When coring, pay attention to the effective height of coring to avoid the influence of core failure in the hole on the next hole sweeping.

9.5.5 Main technical and economic conditions of the test

According to statistics, the footage of this casing drilling test is 157.34m, and the main technical and economic indicators are as follows.

(1) time utilization rate

The total testing time is 386.3 hours, in which: the drilling time is 2 15.75 hours, the auxiliary time is 1 14.92 hours, and the downtime is 55.67 hours. ..

(2) Drilling efficiency

The number of test-bed months is 0.537, and the monthly efficiency is 293m/ month. The average aging time is 0.73m/h, the highest aging time is 1.54m/h, and the main test hole section is about1m/h.

(3) Return footage

Test 138 times, average footage 1. 14m/ time, maximum length 2.80m/ time.

(4) Delivery and assistance

1) was put into operation 138 times, and was successfully deployed once, accounting for 97. 134 times; After the drilling tool was delivered, the stuck tool was fished out, and then it was opened four times, accounting for 3%.

2) Fishing times: 138 times: 13 1 time, accounting for 94.93%; 7 failures, accounting for 5.7%.

Fishing condition of well interval: 25.84 ~ 50.65 m well interval (initial stage of test), fishing for 20 times, and failure for 7 times due to improper debugging and cooperation of drilling tools; 50.65 ~ 183. 18m hole section, fishing 1 18 times, success18 times, success rate 100%.

(5) Drilling lifting interval

Drilling times 12 times, of which: 8 times in the interval of 25.84 ~ 50.65 m, mainly due to improper debugging of φ 1 14 casing coring tools and fishing failure (large resistance of main drilling tools); 50.65 ~ 183. 18m interval was used for 4 times, 1 time was due to mechanical failure (failure of water pump and drilling rig takes a long time to repair), and 2 times was due to abnormal sound of drilling tools in the well. 1 time was used for auxiliary drilling tools at the bottom of casing lifting.

Average lifting interval 13. 1 1m, maximum lifting interval 135.52m (excluding non-drilling tool failure factors).

(6) Life of φ 94 bit

Main bit (94mm): Hot-pressing bit is not suitable for formation due to its low rotation speed, and the service life of electroplating bit is ≥ 50m; The service life of the auxiliary bit is ≥50m.

(7) Core recovery rate

Core length 155.59m, and core recovery rate is 98.88%.

(8) Drilling bending

According to the inclinometer data (Table 9. 18), the borehole inclination meets the specification requirements.

Table 9. 18 ZK950 1 borehole inclinometer data (0 ~ 160m hole section)

Note: The inclinometer is a gyro inclinometer (produced by Shanghai Geological Instrument Factory).

9.5.6 Existing Problems and Suggestions

During the production test, the following main shortcomings and improvements were found in BH- 1 14 casing drilling:

1) The concentricity of the main and auxiliary drilling tools is poor and the connection rigidity is insufficient. During drilling, the main drill swings, which affects the rotation stability of drilling tools and makes it difficult to drill at high speed, resulting in eccentric wear of the main drill (Figure 9.438+03). It is suggested to strengthen the righting and guidance of auxiliary drilling tools and hole wall, main drilling tools and auxiliary drilling tools to improve the stability of main drilling tool suspension system.

Figure 9. 13 Problems caused by poor concentricity of drilling tools

2) Casing drilling in geological exploration is a brand-new drilling technology, and the adopted caliber and specifications are all new standards. At present, there is a lack of fishing tools to deal with accidents in wells. It is suggested to equip the well with accident handling tools or reserve special interfaces for accident handling tools. Fig. 9. 14 shows a self-made fishing tool, and fig. 9. 15 shows an accident drilling tool salvaged.

Figure 9. 14 Self-made fishing tools

Figure 9. 15 Accident drilling tools salvaged

3) When the drilling tool is in place, the pump pressure alarm of the auxiliary drilling alarm system is not obvious, and the accuracy of the alarm system needs to be improved for the operator to judge.

4) In order to better improve the drilling efficiency and return length of casing drilling, and avoid the blockage of broken formation, it is suggested to add a hydraulic impact hammer system to the main drilling tool.

5) It is recommended to use a short main drilling tool of about 0.5m to drill about 0.5m before normal drilling.

6) In order to serialize casing drilling technology and meet the actual needs of drilling, it is suggested that the development and production test of φ 91φ 75 casing drilling tools should be carried out as soon as possible.

Understanding and experience

Casing drilling is a new technology of geological exploration drilling in China, which has unique technical characteristics and advantages in protecting borehole wall in complex strata. It only needs one drilling process, that is, it can complete the tasks required by conventional wireline coring drilling and "open hole coring drilling-casing running". This technology is simple, safe and reliable, which can effectively solve the problem of wall protection in complex strata and reduce the labor intensity of wall protection. The test shows that as long as the low solid mud is scientifically prepared and used, the bit and drilling technical parameters are reasonably selected according to different formations, and the casing drilling operation is carefully implemented, the complex formation can be effectively and quickly crossed and the casing wall can be protected. Therefore, we believe that this technology has high popularization and application value in deep geological exploration and drilling.