Iranian engineers have helped design “special” drilling bits which are used in one of the most challenging oilfields in Iran.
In the 2000s, the Norwegian Norsk Hydro drilled three exploration wells in western Iran where two major oilfields of Azar and Changuleh are located, but the company gave up the drilling operation in one of the wells in the Azar oilfield after about one year, due to the geological difficulties they faced during the operation.
Vahab Hassani, technical and operation manager at Dana Energy, says the field has formations with complicated and unexpected behavior and properties, and engineers need a “very special” technology to drill them.
Dana Energy, the major provider of drilling bits to the operators of the Azar field, however, came up with an idea to improve the design of the drilling bits used in such challenging oilfields particularly in long 24” section as Azar – a field Iran shares with neighboring Iraq. It should be noticed that 14 / 14 ¼” and 12 ¼” sections need specific bicenter bit or reamers.
The joint field, which has 2.5 billion barrels oil in place, is one of the hardest fields to explore, according to Hassani. “There are special sections in the Azar field, which are so difficult to drill, but our engineers have come up with an idea that could resolve the problem, running drilling bits with a longer working life to reduce trip time,” he said.
The bits which can drill 24-inch-large holes in this field generally drill less than one meter per hour in the lower part of the section. Even Norsk Hydro, which had access to the best technology at the time, had used 24 conventional roller cone bits in AZ-02 well while it was working on the field to drill a 2000 meter hole, Hassani noted.
Dana Energy suggested their Chinese partner, which manufactures drilling bits for the company, to produce a new polycrystalline diamond compact (PDC) bit based on the design offered by the Iranian side. PDC bits have more strength, but they are not usually used for 24-inch holes, Hassani said.
“Yet, we designed a special PDC bit to be used for drilling the 24-inch hole in the Azar field, an effort that eventually resulted,” he said.
Hassani said the newly-designed PDC bits helped operators to increase the average drilling rate in the depth of 1000-2000 meters to more than three meters per hour. Meanwhile, the number of bits used for the particular section has reduced to two – a roller cone bit and a PDC bit, he added. The result is a significant reduction in drilling cost compare to before.
Technical and Operation Manager
Drill Bits and Downhole Tools