“When we penetrated the Upper Triassic formation between a depth of 3,000 and 3,270 meters, we discovered a sandstone interval with intensive oil shows recorded on shaleshakers and ditches along with degassing of drilling fluid,” said Toleush Tolmakov, general director of BMB Munai's operating subsidiary in Kazakhstan. “Although unexpected, this Upper Triassic interval was subsequently confirmed by electric logging conducted by Baker Atlas.”
“Based upon our interpretation of a recently completed 3D seismic study, our original goal was to have our contract driller, Oil and Gas Exploration Kracow, extend the depth of the existing well from 3,069 meters to 3,800 meters, through the Middle Triassic formation,” added Tolmakov. “During the reaming of the existing wellbore, we discovered that the technical condition of the well had deteriorated significantly from the condition described in the original drilling logs. Because of the poor conditions within the wellbore, we began a sidetrack at 1,660 meters and essentially drilled a new bore from that depth.”
“When we penetrated the Middle Triassic formation between 3,356 meters and 3,361 meters we encountered very high formation pressure, additional intensive oil shows and a substantial increase in the gas content in drilling fluid,” continued Tolmakov. He noted that, as a safety precaution, the company compensated by increasing drilling fluid weight. The increased weight of the required drilling fluid showed the company that the Middle Triassic formation is characterized by abnormally high pressure of approximately 600 atmospheres.
“Due to the high weight of the drilling fluid, beginning at 3,361 meters there was a loss circulation within the wellbore,” said Tolmakov. “Analysis of electric logging data determined that the loss circulation area was located at a depth between 1,660-1,860 meters. Therefore, we separated the loss circulation from the inflow by installing a cement plug and running casing to the depth of 3,100 meters.”
Due to high pressure and strong degassing of drilling fluid in the penetrated portion of the Middle Triassic formations, the company's operations managers decided to stop drilling at the depth of 3,361 meters and retain Kezbie, a Kazakhstani company, to commence well completion operations. BMB Munai now plans to purchase casing liner and run-in casing until the depth of 3,356 meters to isolate the test production area of the Upper Triassic formation.
“Following installation of the liner during the coming weeks, the company will ream to the penetrated portion of the Middle Triassic formation with coil tubing and test the very upper portion of this formation in an open wellbore,” said Gamal Kulumbetov, BMB Munai’s chief operating officer. “These activities will allow the company to obtain preliminary understanding of the potential of our original target, the carbonate formations of the Middle Triassic, while allowing the company to continue testing the Upper Triassic formation in a cased wellbore.”
Kulumbetov, also noted, "Despite the numerous challenges encountered while re-entering this well, we believe it has been a resounding success. Not only have we gained valuable information that will guide our exploration and appraisal activities in the entire Kariman field, we have discovered a new producing oil-bearing horizon in the Upper Triassic formation and confirmed the high potential of the Middle Triassic formation."
BMB Munai is an independent oil and gas company engaged in the exploration, development and production of crude oil and natural gas in Western Kazakhstan. The company maintains administrative offices in Salt Lake City, Utah, and Almaty, Kazakhstan.
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