Antech completes final phase of coiled tubing drilling program in Kansas Niobrara
EXETER, England – AnTech Ltd, a directional drilling and design engineering services company serving the upstream oil and gas industries, announced that it has successfully completed the drilling of the final two wells of a five-well coiled tubing drilling (CTD) campaign in shallow reserves of the Kansas Niobrara Formation in the United States.
Drilling of the final two wells, which were horizontal, demonstrates that AnTech’s POLARIS™ CTD bottomhole assembly (BHA) performs reliably when drilling horizontally, in addition to the deviated and S-curve wells drilled in the previous operations.
Located on the Colorado-Kansas border, the build sections of the final two horizontal wells were drilled with mud using an 8-1/2-in. bit. The horizontal sections were drilled with an air mist using a 6-1/4-in. bit. Air was used for these wells because the formations were highly fractured and were unable to hold the pressure of a liquid column.
The first horizontal well was drilled to 1090-ft. TVD and over 1450-ft. lateral displacement. The team then carried out the second operation, another horizontal well drilled to 1096-ft. TVD with a lateral displacement of 1103-ft. As in the three previous directional drilling operations carried out, the 5-inch POLARIS was easy to steer, reconfirming the effectiveness of the solid state gyro system and its overall ability to drill directional and horizontal wells.
The AnTech team worked in conjunction with a CTD specialist using one of its fleet of hybrid land rigs. By using a hybrid drilling rig, drilling time is often reduced, and the same company had demonstrated on previous vertical wells that they could reduce the drilling time from seven to two days, compared to a conventional jointed pipe rig.
Effective drilling of S-curve, deviated and horizontal wells
The success of the final phase of this drilling programme follows on the heels of the deviated and S-curve wells previously drilled in late 2011.
Overall, the programme demonstrated that the POLARIS is capable of directional and horizontal drilling of wells with hole sizes ranging from 6.25-in. to 8.5-in., using mud and air as a drilling fluid, whilst showcasing the ability of its AcrobatTM gyro system. This is the first time that a solid state gyro has been used for directional measurement while drilling, providing reliable data at all inclinations (vertical, horizontal and during the build section), allowing orientation to be carried out accurately, even while in the casing.
It also provides evidence of operational benefits that make it possible for operators to drill wells in shallow reserves cost-effectively, with minimal environmental impact. Precise well plans can be followed and well paths can be optimised by kicking off early (with the gyro still within the casing) and reducing build rates, making it easier to run casing without losing valuable depth. Finally, the campaign illustrates the potential for pad drilling with CTD because the POLARIS tool makes it possible to drill multiple wells from the same pad, safely and accurately.
“For years, the industry has been looking for an effective solution that combines the well- proven speed and efficiency of CTD with a directional capability that can not only drill hole sizes up to 8-1/2-in. and drill underbalanced to avoid over pressurizing the reservoir, but can orient while remaining in the casing,” said Toni Miszewski, Managing Director of AnTech. “The fact that we were able to achieve this during the Niobrara drilling programme demonstrates that the new POLARIS provides a field-proven solution in the form of a gyro- steered BHA for use on coil,” he added.
Accessing untapped reserves
Looking ahead, AnTech is confident that the POLARIS system holds the key to unlocking reserves in mature oilfields and in shallow reserves previously thought to be commercially unviable, especially in the USA. The success of the recent Niobrara drilling programme represents a crucial step forward in its drive to establish itself as a key player in the directional drilling services arena.