Serinus Energy Inc. (Serinus, SEN or the company), an international upstream oil and gas exploration and production company, reported Friday that the Lukut Updip-1 (LKU-1) well in Brunei Block L flowed gas continuously from two separate intervals that have not previously been penetrated by any wells onshore Brunei. While the rates were estimated at less than 50 thousand cubic feet per day (Mcf/d), the discovery of hydrocarbons within these zones indicates that further analysis and appraisal will be required to evaluate the resource potential of this play.
Test 1 (6,992 - 7,011 feet)
The LKU-1 well encountered a drilling break and a significant influx of gas with a total gas reading of 47 percent whilst drilling 6 inch hole starting at a depth of approximately 6,992 feet (2,131 meters) measured depth (MD) 5,817 feet (1,773 meters) true vertical depth subsea (TVD) and continuing to a depth of at 7,011 feet (2,137 meters) MD, the last 9.8 feet (3 meters) of which is interpreted to be clean sand. C1 gas readings peaked at 332,000 parts per million (ppm) and C5 gas readings peaked at 628 ppm at TD. Pressures rose significantly and there was material gas influx with total gas readings increasing to 47 percent which resulted in gas being flared at surface for several hours. The mud weight was subsequently increased to 17.7 pounds per gallon (ppg) to control the calculated formation pressure of 5,366 pounds per square inch (psi). Due to the significantly higher than expected formation pressures and equipment limitations, the company determined that it could no longer safely continue to drill the LKU-1 well and, consequently, a cement plug was put in place from 6,955 (2,120) to the total MD of 7,011 feet (2,137 meters) and 4.5 inch casing was set to a depth of 6,955 feet (2,120 meters). The initial planned depth for the LKU-1 well was 9,708 feet (2,959 meters) MD and 7,907 feet (2,410 meters) TVD.
The first zone to be tested was the bottom 19.7 feet (6 meters) of the well from 6,992 to 7,011 feet (2,131 to 2,137 meters) MD over which the cement plug had been placed. Gas flowed continuously at a low rate during the test. The formation is believed to have been damaged by heavy drilling fluid, mud system additives and cement during the drilling process as the drilling team worked to control the high pressures encountered. Attempts to clean up the perforated interval by utilizing an acid treatment were not successful.
Test 2 (6,496 to 6,955 feet)
During the drilling operation a general trend of increasing silt and/or sand content was observed from a depth of approximately 6,201 feet (1,890 meters) and continuing to 7,011 feet or 2,137 meters (a total thickness of 810 feet or 247 meters). The sandy/silty shale encountered over this section appears to be hydrocarbon charged, with C1 to C5 total gas readings increasing from a 32.8 foot (10 meter) average of 0.49 percent at 5,577 feet or 1,700 meters MD to a 32.8 foot or 10 meter average of 8.1 percent at 6,923 feet or 2,110 meters MD. C1 gas readings steadily increased from a 32.8 foot or 10 meter average of 3,150 ppm at 5,577 feet or 1,700 meters MD to a 32.8 foot or 10 meter average of 58,000 ppm at 6,923 feet or 2,110 meters MD. Based upon the increased pressures and associated hydrocarbon shows, the thick silty shale zone was selected as the second zone to be tested.
A total of 197 feet (60 meters) was selectively perforated between the depths of 6,496 feet (1,980 meters) and 6,955 feet (2,120 meters). Gas was flared at surface throughout the test but the well did not produce at commercial rates. The entire section tested in the second test, which was open during the well control efforts, is believed to have also been damaged by drilling fluid and mud additives.
The section of the LKU-1 well below approximately 3,609 feet (1,100 meters) MD has not previously been penetrated by any wells in onshore Brunei. The drilling break at 6,991 feet (2,131 meters) MD is interpreted to correspond to the top of a zone defined by seismic (the Green Zone) that was a secondary target of the well. The deeper primary target of the well (the Red Zone), which the company expected to encounter at 7,881 feet (2,402 meters) MD, has not been penetrated. The Green Zone, the transition zone above the Green Zone (Test 2) and the Red Zone are all interpreted to be facies associated with turbiditic sandstone deposition which are likely to extend over a large area. The company believes that the tested formations may be capable of producing at commercial rates, and that further analysis, evaluation and appraisal will be required to fully assess the prospectivity and productivity of this new play.
Jock Graham, chief operating officer of Serinus indicated that “while the well did not reach the primary target and the secondary targets appear to have been damaged, the presence of sandstone reservoirs within an interpreted deep water shale package suggests that the geological model of turbiditic sandstone deposition is correct. In addition to the presence of reservoir sands, LKU-1 also demonstrated both pressure and the presence of hydrocarbons, suggesting that the elements required for a successful pool may be present within this prospect.”
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