Poland: Early core results from shales encouraging

By OGJ editors

Early core analysis results from shales in the Baltic basin are “cautiously encouraging,” said BNK Petroleum Inc., Camarillo, Calif.

The preliminary analyses by consulting engineers are for the Wytowno S-1 and Lebork S-1 wells on the adjacent Slawno and Slupsk concessions. The Ordovician-Cambrian interval in the Lebork S-1 well looks better than any other log BNK has seen in the basin, the company said.

The following data from the Lebork S-1 well is only from sidewalls taken in the lower part of the Ordovician and the Alum shale, as the whole core analysis from above these intervals is not yet completed.

The additional core analysis data for the target intervals in the Lebork S-1 well and the final core analysis reports for both wells are expected to be in by the end of August, at which time the log analyses for both wells will be reprocessed with the core data.

In Lebork S-1 porosity in the 47-m thick Ordovician-Cambrian interval averages 4% and ranges from 0.98% to 5.2% and in Wytowno S-1 porosity the 91-m thick Lower Silurian target interval averages 3% and ranges from 1.1% to 4% while porosity in the 40-m thick shallower Lower Silurian interval is 5.6%.

Gas-filled porosity in Lebork S-1 porosity ranges from 0.8% to 3.9% and averages 1.8% of bulk volume in the Ordovician-Cambrian. In Wytowno S-1 the Silurian targets range from 0.3% to 1.6%, averaging 1.1% of bulk volume, with one shallower Silurian interval that has a value of 4.3% of bulk volume.

Lebork S-1  had average desorption values of 40 scf/ton over the Lower Silurian and 268 scf/ton over the 47-m Ordovician-Cambrian interval. The Lower Ordovician-Cambrian shale in Lebork S-1 had intervals as high as 451 scf/ton. Wytowno S-1 had average desorption values of 124 scf/ton in the Lower Silurian target interval and 77 scf/ton in the shallower Lower Silurian interval. For comparative purposes, BNK’s Oklahoma Woodford shale Tishomingo field has average values of 104 scf/ton.

Wytowno S-1 thermal maturity values were estimated from the reflectance of pyrobitumen and the thermal alteration index obtained from palynological (micropaleo) analysis of the drill cuttings, which both equate to an Ro of 1.8 in the Lower Silurian. The TAI for the Lebork S-1 cuttings from the Lower Silurian to Ordovician-Cambrian are also equivalent to an Ro of 1.8, which places the thermal maturity for both wells in the dry gas window.

In Wytowno S-1 the total organic carbon is variable across the Lower Silurian target interval, ranging from 0.1 to 1.3 wt %. The TOC data from the Lebork S-1 well are not yet available, but both the log- calculated values and SEM image analysis values indicate multiple times higher TOCs across the Ordovician-Cambrian shales.

Meanwhile, the Starogard S-1 well on the Starogard concession in Poland, in which the  company has an indirect 26.69% interest, was spud on July 16, 2011, and is drilling at 1,700 m after setting 690 m of surface casing. Another casing string will be set at 2,050 m before drilling to the estimated core point and coring the rest of the well.

Completion of the Lebork S-1 and Wytowno S-1 wells is to start in mid-September. The company is also reviewing the possibility of performing the completion of the Starogard S-1 well in conjunction with the two other wells. Well results and equipment availability will determine the timing.

The company will use bladders to hold the fresh water for fracture stimulating the well instead of digging a large pit.

BNK has secured approval to shoot 740 line-km of 2D seismic of which 407 line-km is on the Saponis and 333 line-km is on the Indiana concessions. In addition, the three Indiana and three Saponis concessions were extended to provide BNK enough time to shoot the seismic before drilling the first three wells in Indiana and the second three wells in Saponis. Seismic shooting is to begin in the fourth quarter of 2011.

Incorporating the micropaleo and high-resolution stratigraphic analysis into the geological picture showed that the Wytowno S-1 well was drilled on a localized paleotopographic high and what was

originally interpreted as Ordovician-Cambrian shales are actually Lower Silurian hot shale intervals.  The intervals in Lebork S-1 have also been revised on the basis of the micropaleo and high-resolution stratigraphic analysis, resulting in slightly different thicknesses of the various intervals.

In addition to the seismic program, BNK has contracted a depth to crystalline basement study. The study will cover a large portion of northeast Poland, fully encompassing the Saponis and Indiana owned acreage. Interpretation of the study is expected to allow the company to better understand general basin geometry, identify subbasins, and locate basement-related faulting. The study is slated for completion by early September 2011.

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