The Gapowo B-1 well on the Bytow concession in Poland encountered overpressured shales in Lower Silurian and Ordovician and greatly elevated gas readings over those in wells on the Saponis concessions.
BNK Petroleum Inc., Camarillo, Calif., said the well, operated by its Indiana Investments Sp. z o.o. subsidiary, was drilled to 4,300 m to evaluate the Silurian, Ordovician, and Cambrian Alum shales. The elevated readings were encountered despite the much heavier drilling mud used in Gapowo B-1 and slower penetration rates.
Geologic data validate the company’s previously disclosed geologic model, BNK said. At Gapowo B-1, the Ordovician shale thickness was 45 gross m compared with 27 gross m in the Lebork S-1 well.
Early data indicate that the most prospective shale intervals in the Lower Silurian in Gapowo B-1 are 40-75 gross m thick out of 120 m of Lower Silurian that had significant gas shows. This is in contrast to Lebork S-1, where in the Lower Silurian the company only considers a few meters to be prospective.
The Lower Silurian at Gapowo B-1 also appears to have higher total organic carbon than the company’s other wells. The higher estimated TOC is based on the strong gas shows, mud log descriptions, and core gamma visual core inspection.
The shales in both the Silurian and the Ordovician are described by the mud loggers as visually dark black, friable shale and occur over the same intervals that generated the large gas readings. These are better and darker descriptions than in any of the other wells that BNK has drilled in the Baltic basin.
After Gapowo B-1 reached TD, difficulty was encountered in obtaining wireline logs over the potential interval due to overpressured, heaving shales in the target intervals, causing large borehole washouts.
As a result of these large borehole washouts, logging while drilling tools were substituted and data capture was reduced. The washed out intervals are the same shales described by the mud logger as being dark black and also correspond to the intervals that gave the very large gas readings.
BNK obtained 177 m of whole core over the Lower Silurian, Ordovician, and Cambrian intervals that will provide additional necessary data moving forward. Processing is under way on the whole core, which will undergo the comprehensive suite of core analyses.
Gapowo B-1 is suspended awaiting reentry, and the rig is moving to deepen the Miszewo T-1 well. The company will reenter and complete Gapowo B-1 after receiving full concession modification approval that allows the drilling of horizontal wells.