Abstract

In an attempt to provide better annular zonal isolation between productive (gas producing) and nonproductive (water bearing) intervals an unorthodox program was proposed and implemented based upon the incorporation of Quick Quenched Blast Furnace Slag (QQBFS) to both the drilling mud (universal fluid) and cement slurries. To date this is the deepest 7500 to 7900 ft (2345 to 2407 m) and hottest (225 F / 107 C bottom hole static temperature) dual application of QQBFS in the industry. A four phase program of progressive steps were taken with respect to field application during this project to implement cost saving measures without sacrificing quality services. During this project, fourteen dual 2 7/8" (7.30 cm) 6.5 lb/ft (9.67 kg/m) N-80, EUE production strings were successfully completed within 9.875/8.75 inch (25.08/22.225 em) hole. A dramatic reduction in remedial squeeze operations has been reported with no squeeze jobs being performed on the last seven (7) wells completed. This type of success will benefit not only operators but state and federal regulatory bodies who are seeking to determine the "field worthiness" of QQBFS as a hydraulic material alternative for the oil and gas industry.

Introduction

The Stratton Field is an established development program some 56 years old, located in Nueces, Jim Wells and Kleberg counties, Texas. Currently the operator has approximately 783 producing wells. A specific area within the Stratton Field known as the Wardner Unit contains 235 leases. Daily, gas and oil production from this field totals 82 million scf (2322240 m3) and 1000 barrels (159 m3). The Stratton Field is approximately 4 miles (6.4 km) wide and 15 miles (24.14 km) long, located 30 miles (48.3 kin) west southwest of Corpus Christi, Texas. Figure 1 illustrates the specific location of wells involved in this project. The productive intervals are Oligocene Frio and Vicksburg sandstones.

The Frio and Vicksburg sands (Stratton Field) have been vigorously developed over the past 50 plus years as a part of twenty-nine (29) multi-reservoir fields which skirts along the Frio fault zone paralleling the Texas Gulf coast. The Frio reservoir consists of compartmentalized fluvial deposits and near shore barrier bars and strand plain sands deposited on the margin of the Norias Delta System. The Frio sands can vary in porosity between 18 and 20%. Permeability of the Frio sand range from 200 to 250 millidarcies Individual pay thicknesses range from 7 to 25 ft (3 to 7 m). However, the Frio formation can be as much as 3000 ft (914 m) thick. This translates into reservoir which may contain over 20 producing horizons. Combine this with the fact that these multiple horizons will vary in bottom hole pressure from 200 psi (1.38 MPa) to over 3000 psi (20.7 MPa) and one can easily see a somewhat difficult task ahead with respect to drilling and completions. See Figure 2 for an open hole log example of a portion of the Frio interval.

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