The use of drill pipe in the Oil and Gas Industry has many applications including but not limited to drilling, squeeze cementing, running and cementing liners, drill stem testing, underbalanced perforating, underbalanced drilling, fracturing, acidizing and gravel packs. Any failure in drill pipe connections due to leaks will be very detrimental to any of these operations and result in additional expenses to the operator. Fortunately, these types of failures can be minimized, if not eliminated, by the use of nondestructive inspection techniques and external testing of tool joint connections.

Statistics show that approximately one out of every 57 drill pipe connection will leak under pressure. The majority of these leaks are due to damaged or dirty shoulder seals of the tool joints. External testing, with the pipe in tension, is a fast, safe, reliable and economical way to detect and correct leaks in drill pipe connections. It has proven itself repeatedly. A most recent case in point was in south Louisiana where an operator attempted 2 unsuccessful squeeze attempts. On the third try they decided to pressure up on the drill string every three stands to attempt to find the leaks, a process which took over three days and did not solve the problem. Upon learning of Gator Hawk's capability of testing drill pipe, we were called out to the location. In less than 17 hours and 13 leaks corrected later, the operator was in the hole performing a successful squeeze job.

The next time you have one of the these situations, you will be time and money ahead to use external testing to help achieve a successful operation.

Industry Applications

Drill Stem Testing

The primary purpose of drill stem testing is to evaluate a variety of data to help design the most efficient operating system for that well. A connection leak will not permit accurate data acquisition. This will result in abandonment of the test requiring a retest and could create an undesirable well control situation. The benefits of performing combined tubing conveyed perforation and drill stem test could be voided in the event of an untimely connection leak.

Cement Squeeze Jobs

A key to the success of a squeeze-cementing job is that of placing the cement at the desired point or points necessary to accomplish the purpose. It is important not to have any leaks in a squeeze string. A leak will permit rapid local dehydration of the slurry and consequent plugging of the squeeze string, resulting in a squeeze job on the squeeze string, rather then the point intended. Therefore it is important to test the casing and the squeeze string prior to mixing the cement. When running and cementing a liner in an oil or gas well, it is important that the liner and the drill string being used are leak free. Once the liner is on bottom and cementing begins it is important that the cement goes where it is supposed. It has been reported where a leak in a drill string created cement returns to the surface while cement was still being mixed, resulting in abandonment of the primary cement job, requiring numerous squeeze jobs to achieve an adequate cementation of the liner.

Fracturing

In some cases, the formation that contains the oil or gas is layered such that the flow of oil or gas is restricted by the formation. In these cases, the Oil Company may elect to do a "frac" job on the formation. In this case, fluid is pumped down the pipe in high volumes at high pressures back into the formation. This causes the formation to open up creating cracks or fissures in the formation. Generally along with the fluid, material is pumped in that will prop these fissures open and also allow for easy flow of the oil or gas through the new material in the fissure to maximize production. A leak is detrimental here, as it may not allow maximum pressure and flow rates at the formation to properly "frac" that formation, as fluids would be escaping through the leak rather than into the formation.

Connection Washout Prevention

During the drilling process, washouts due to leaks can cause problems with parting of the drill string, drilling inefficiencies due to higher pump pressures to achieve necessary downhole flow rates of drilling fluids and premature tripping of drill pipe to correct a leak. This is most critical when using a diamond bit where the objective is to stay on bottom, drilling for extended periods of time.

Underbalanced Perforating

There are cases where many operators use drill pipe to perform tubing conveyed perforation techniques and/or perform drill stem testing. When tubing conveyed perforating techniques are used, they are usually done with a limited column of fluid in the drill string or tubing to create a positive pressure differential from the formation to the well bore. This allows for an immediate back surge after perforating, which will result in cleaner perforations and better well productivity. This is a direct application for external testing of the drill string or tubing connections since an external pressure differential is existent prior to and possibly even after perforating.

Liner Operations

When running and cementing a liner in an oil or gas well, it is important that the liner and the drill string being used are leak free. Once the liner is on bottom and cementing begins it is important that the cement goes where it is supposed to. It has been reported where a leak in a drill string created cement returns to the surface while cement was still being mixed, resulting in abandonment of the primary cement job, requiring numerous squeeze jobs to achieve an adequate cementation of the liner.

Underbalanced Drilling

Underbalanced Drilling Operations require the utmost attention to detail. Any problem associated with a connection leak can have disastrous and costly implications. External Testing of drill pipe connections is inexpensive risk management compared to the expense of dealing with resolving a connection leak.