Make a Connection (Drilling)

What Is Making a Connection?

Making a connection (also called a pipe connection or simply a connection) is the drilling operation of temporarily stopping rotation and circulation to add a new joint or stand of drill pipe to the top of the drill string as the bit advances and the kelly bushing or top drive reaches its lowest allowable position. A single joint of drill pipe is approximately 30 feet (9 m) long, and a stand (two or three joints screwed together in the derrick) is 60 to 90 feet (18 to 27 m), so connections occur every 30 feet when drilling single joints or every 90 feet when tripping stands. Each connection represents a brief but critical window during which wellbore pressure is reduced, circulation is halted, and formation fluids have an opportunity to enter the wellbore if bottomhole pressure falls below pore pressure.

How Making a Connection Works

A conventional pipe connection follows a well-defined sequence. When the kelly or top-drive quill approaches its lowest position, the driller picks up on the elevator to take the weight of the drill string off the bit, stops rotation, and shuts down the mud pumps. The kelly is broken out from the top of the drill string using pipe tongs, lifted into the rathole, and a new joint of drill pipe is picked up from the pipe rack and spun into position using the rotary table or iron roughneck. The connection is made up to the specified makeup torque using hydraulic tongs, the kelly is screwed back on top, and pumps are brought back on line slowly to restore circulation before rotation is re-engaged and drilling resumes. The total time from stopping the bit to resuming drilling is the connection time, and it is carefully tracked as a key performance indicator. World-class operations achieve consistent connection times under 4 minutes; poor performance on a complex well can add hours of flat time per day and significantly increase well cost.

The most operationally important consequence of a conventional connection is the pressure transient it creates in the wellbore. When mud pumps are shut down and the drill string stops rotating, the equivalent circulating density (ECD) drops to the static mud weight immediately. In wells where the mud weight window between pore pressure and fracture gradient is narrow, this pressure reduction can allow formation gas or liquid to migrate into the wellbore, a phenomenon called connection swab. The gas that enters during this static period is called connection gas, and it appears as a repeating series of background gas peaks on the mud log, one peak approximately every 30 feet corresponding to each single connection. Connection gas is distinct from a kick in magnitude but is monitored carefully because a trend of increasing connection gas peaks can indicate that mud weight is inadequate or that the wellbore is approaching a naturally fractured or overpressured zone.

Makeup torque is a critical quality-control parameter for every connection. Each drill pipe size and grade has a published optimal makeup torque range from the pipe manufacturer and from standards such as API RP 7G. Under-torqued connections can back off (unscrew) during drilling, potentially dropping the bottom-hole assembly into the well, while over-torqued connections can yield the pipe body or damage the tool joint thread, causing a washout or string failure. Tong-line measurements, hydraulic torque gauges on iron roughnecks, and, on modern rigs, top-drive torque monitoring are all used to confirm that each connection is made to specification and that the torque-turn curve matches the expected thread engagement profile.

Managed Pressure Drilling and Continuous Circulation

Managed pressure drilling (MPD) was developed in large part to address the pressure transients caused by conventional connections. In MPD, a rotating control device (RCD) on the wellhead and a surface choke manifold work together to maintain a constant backpressure on the annulus, precisely controlling bottomhole pressure independent of pump rate. When pumps shut down for a connection, the surface choke closes automatically to compensate, holding bottomhole pressure constant throughout the connection sequence. This eliminates connection swab and the associated risk of gas influx, making MPD particularly valuable in deepwater wells, high-pressure/high-temperature (HPHT) environments, and any well where the mud weight window is less than 0.5 ppg.

Continuous circulation valves (CCVs) take the concept further by allowing mud to flow through the drill string continuously even while a new joint of pipe is being added at the rig floor. The CCV is a valve assembly installed in the top of the drill string that allows a bypass flow path through a sideport while the upper connection is broken out. A high-pressure hose connects the standpipe to the sideport so mud circulation continues uninterrupted. CCVs are particularly effective at preventing connection gas in gas-prone formations and at improving wellbore cleaning by eliminating the settling of cuttings beds during the static period of a conventional connection. They add complexity and cost to the rig floor operation but deliver measurable benefits in well control risk reduction and wellbore quality.

Make a Connection Synonyms and Related Terminology

• pipe connection -- the generic term for adding a joint or stand to the drill string; used interchangeably with "making a connection" on most rigs
• single connection -- a connection made by adding one 30-foot joint of drill pipe rather than a pre-assembled stand
• stand connection -- a connection made by adding a pre-racked stand of two or three joints (60 to 90 feet), reducing the number of connections needed per 1,000 feet drilled
• make-up torque -- the specified torque applied to the threaded connection between two joints of drill pipe to achieve a leak-proof, mechanically sound joint

Related terms: drill string, kelly, equivalent circulating density, connection gas, managed pressure drilling, kick

Frequently Asked Questions About Making a Connection

What causes connection gas and is it a sign of a kick?

Connection gas is caused by the temporary reduction in bottomhole pressure that occurs when mud pumps are shut down for a pipe connection. Without the friction pressure of circulating mud adding to the static hydrostatic head, bottomhole pressure drops, and a small amount of formation gas migrates into the wellbore annulus. When circulation resumes and the gas is pumped to surface, it registers as a peak on the gas chromatograph. Connection gas is not the same as a kick: it is typically small in volume, consistent in depth spacing (every 30 or 90 feet), and does not cause measurable pit gain. However, if connection gas peaks are increasing in magnitude from one connection to the next, or if a connection produces a significantly larger peak than usual, this warrants investigation because the well may be underbalanced.

How is connection time measured and who tracks it?

Connection time is measured from the moment the mud pumps are shut down (drilling stops) to the moment the pumps reach full operating pressure after the new joint is made up and circulation is restored. On modern rigs, this is captured automatically by the rig's data acquisition system (WITS or WITSML feed) and reported in real time to the company man, drilling engineer, and operations center. Historically, the driller and toolpusher tracked connection times manually using a stopwatch and entered them on the morning report. Third-party drilling performance analysts compile connection time statistics into trend charts to identify crews, shifts, or specific pipe sizes that are slower than average and to benchmark performance against offset wells.

What happens if a connection backs off downhole?

A connection back-off (unintended unthreading of a drill pipe joint in the wellbore) is a serious drilling incident. It is usually caused by an under-torqued original makeup, excessive left-hand torque from reactive formation, or fatigue at a worn tool joint. When a connection backs off, the bottom-hole assembly and lower drill string separate from the upper string and fall to bottom or become stuck in the wellbore. The well must be secured, and a fishing operation is required to retrieve the dropped string. Depending on depth and wellbore geometry, fishing can take days and cost hundreds of thousands of dollars. Modern rigs use makeup torque recorders and, in critical operations, thread-locking compounds to minimize back-off risk.

Why Making a Connection Matters in Oil and Gas

Every foot of well depth requires at least one pipe connection, so on a 15,000-foot well a rig crew may make 500 or more connections before reaching total depth. Connection time is one of the largest controllable contributors to non-productive time in drilling operations: shaving two minutes off each connection on a long lateral can recover 16 or more hours of rig time worth tens of thousands of dollars. Beyond efficiency, the pressure management aspects of each connection are fundamental to well control: the brief window of reduced bottomhole pressure at every connection is when many kicks and blowouts have their origin. Understanding connection gas trends, maintaining proper mud weight, and using MPD or continuous circulation technology in challenging wells are all practices that grew directly from hard lessons learned at the connection point. For drilling engineers and company men, optimizing connection procedures and monitoring connection-by-connection data is a daily practice that affects both well cost and safety.