Coalbed Methane Directional Drilling Rig: CMD100 Deep Target Well in Qinshui Basin, China

Executive Summary

In the Qinshui Basin of Shanxi Province — one of China's richest coalbed methane (CBM) provinces — a deep CBM development campaign demanded a directional drilling rig capable of reaching targets below 2,000 m while building a sharply curved wellbore and holding a 900 m-plus lateral inside a thin, pressured coal seam. Conventional rigs on site lacked torque reserve, braking stability and directional control, and suffered stuck pipe and hole deviation. The project deployed the CORTECH® CMD100 smart truck-mounted full hydraulic top-drive drilling rig, paired with a high-precision downhole survey instrument, a high-torque spindle braking system and an air down-the-hole (DTH) hammer drilling process. The well was finished at 2,010 m total depth, a maximum inclination of 88.42° and a 950 m horizontal section, with gas production meeting design expectations. It has become a benchmark for efficient deep CBM development in northern China.

Project Background & Challenge

The Qinshui Basin holds enormous CBM resources, but this particular deep target presented four interlocked drilling problems that set the bar above standard CBM practice:

• Deep burial: the planned bottom-hole exceeded 2,000 m, placing high demands on hoisting capacity, tubular handling and bit life.

• Alternating soft-hard interbeds: frequent transitions between weak and competent strata destabilized the drill string and made trajectory control difficult.

• High build-up curvature: the curve section required aggressive, precisely controlled angle building, and conventional rigs could not hold curvature consistently.

• High lateral resistance: drag in the 900 m-plus horizontal section was high, raising the risk of stuck pipe and hole deviation.

Operators had already observed that ordinary rigs lacked sufficient torque reserve, their braking stability was poor, and directional control could not guarantee wellbore quality — and wellbore quality directly determines CBM recovery efficiency. This project is rated among the hardest directional drilling jobs in the industry.

Our Solution

The contractor selected the CORTECH® CMD100, a 55-ton ultra-heavy-duty, multi-functional full hydraulic top-drive rig built for large-diameter, high-consequence CBM operations including straight, directional and horizontal multilateral wells. Four design choices solved the challenge:

• High-torque top drive for build-up control: the 105 mm thru-hole spindle delivers 27,500 Nm of continuous breakdown torque in the low-speed range (0–100 rpm) for aggressive build-up in hard interbeds, shifting up to 300 rpm (9,700 Nm) when needed — the torque reserve that conventional rigs on the site lacked.

• High-torque spindle braking system: controlled braking on the top drive stabilized the string during angle building and sliding, directly addressing the braking instability and stuck-pipe tendency observed with other equipment.

• High-precision downhole survey instrument: real-time inclination and azimuth measurement allowed the crew to steer the build-up curvature and hold the lateral on the planned trajectory, protecting reservoir contact.

• Air DTH hammer drilling process: air-powered hammer penetration accelerated drilling in hard interbeds, while the rig's 20.6 MPa integrated air/mud/foam manifolds let crews switch drilling methods as formation conditions changed.

Key Results

For the full technical specifications of the CORTECH® CMD100, see the CMD100 product page.

Customer Value & ROI

• Trajectory confidence, fewer sidetracks: precise build-up control and stable spindle braking meant the well reached target in one run, avoiding costly redrills that routinely wipe out the economics of deep directional wells.

• Reservoir contact secured: a 950 m lateral held at 88.42° inclination maximized drainage area against the seam, directly supporting the gas production that met design.

• Method flexibility on one rig: air, mud and foam drilling through integrated manifolds removed the need to mobilize different equipment for changing interbedded conditions.

• Reusable experience: the well established a mature template for similar complex horizontal wells, lowering future program risk across the basin.

FAQ

What makes a rig suitable for deep coalbed methane directional drilling?

It needs high torque reserve for build-up in hard interbeds, stable braking on the top drive to control sliding, a high pulling capacity for deep tubulars, and integrated survey steering. The CMD100 combines a 100 t pullback with 27,500 Nm of low-speed torque and a high-precision downhole survey system.

How does high spindle braking torque prevent stuck pipe in directional CBM wells?

In long laterals, drag rises sharply; controlled braking lets the driller manage string tension during sliding and reaming rather than letting the pipe free-wheel and jam. This was a core reason the CMD100 avoided the stuck-pipe events seen with conventional rigs on the same project.

What build-up curvature challenges occur in deep CBM horizontal wells?

Soft-hard interbeds cause the bit to wander, and an aggressive curve demands consistent steering. Real-time survey measurement plus high-torque rotation lets the crew hold the planned curvature precisely, as in this Qinshui well that built to 88.42° inclination.

How deep can a coalbed methane directional well be drilled?

On this project the CMD100 finished a directional CBM well at 2,010 m total depth with a 950 m lateral, exceeding the design targets of >2,000 m depth and >900 m lateral.

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