McCully propane frac wells decline, AVO tried

By OGJ editors
HOUSTON, Feb. 19 -- Gas production at two wells in McCully field in southern New Brunswick have declined after encouraging initial rates, and separately the operator is evaluating the amplitude variation with offset technique to identify areas for infill drilling.

The $28.6 million 2010 capital budget of Corridor Resources Inc., Halifax, NS, includes funds for drilling two McCully Hiram Brook wells and is based in part on field output averaging 19.5 MMscfd vs. the 23 MMscfd previously estimated. This is because the McCully L-38 and P-47 wells appear to be on hyperbolic decline trajectories and have fallen to 1 MMscfd/well from test rates of 5 MMscfd in the fall of 2009.

Corridor theorizes that the reservoirs may be smaller than indicated by formation thickness, that abundant pyrobitumen reduces reservoir size, or that wax found on wellheads and downhole tools may indicate that rapid pressure drawdown during initial high-rate testing may have led to wax deposition near the well bore.

Early results of a xylene soak-squeeze in the L-38 well indicate the treatment may not be effective, and Corridor is considering restricting flow rates to stem wax deposition in this part of the field.

Corridor also plans to drill the L-37 horizontal well using an oil base mud to minimize formation damage. The company expects that a horizontal well in this part of the reservoir may be free of bitumen and productive without hydraulic fracs. It also may not experience decline rates similar to those at L-38 and P-47. The company will defer the second 2010 McCully well fracs are necessary.

Corridor is building a detailed reservoir model using data from the field’s 30 wells to assess fluid drainage patterns and select infill locations.

The 2010 budget includes funds to drill the Sally’s Brook Hiram Brook prospect 17 km north of McCully field, Corridor’s share of four wells to be drilled on Anticosti Island in the Gulf of St. Lawrence, and performing a site survey for a proposed drilling location on the Newfoundland side of the giant Old Harry structure in the gulf east of Prince Edward Island (see seismic section, OGJ, Sept. 28, 1998, p. 108).

Corridor is seeking a floating rig to drill within 2 years to 4,000-6,000 ft in 1,400 ft of water at Old Harry, where it estimates the potential at 2 billion bbl of oil or 5 tcf of gas recoverable.