The Charco Redondo Thermal Recovery Pilot
Authors: Widmyer R.H. , Howard C.E. , Fontaine M.F. , Haynes S. 
Published: December 2007

A highly instrumented reservoir was steamflooded in 1965 to determine heat losses, formation heat content, location of formation and injected fluids with time, and residual oil saturation. Predicted heat losses were comparable with those determined from field data. The results of a subsequent successful effort to ignite this reservoir following the steamflood also are presented.

Introduction

Thermal recovery methods are used to improve production of heavy viscous crude oils. Steamflooding and production of heavy viscous crude oils. Steamflooding and fireflooding are two methods that have been used extensively throughout the industry. In either application, prediction of reservoir behavior is necessary so cost prediction of reservoir behavior is necessary so cost estimates can be made. In 1965 Bellaire Research Laboratories conducted a fully instrumented pilot steamflood in the Charco Redondo field, Zapata County, Tex. This pilot was followed by an in-situ combustion experiment pilot was followed by an in-situ combustion experiment in the same pattern early in 1966.

The paper is divided into two parts. Phase 1 describes the steamflood, conducted to determine heat losses, location of injected fluids with time, and the residual oil saturations. Phase 2 describes the in-situ combustion experiment, conducted to determine if residual oil saturations following a steamflood were adequate to support combustion.

Phase 1 - Steamflood Phase 1 - Steamflood Reservoir Properties Reservoir properties are itemized in Table 1.

Pattern Pattern As shown in Fig. 1, a 1.01 ha (2.5 acre) isolated inverted five-spot pattern was selected. Injector 111 and Producers 112, 113, and 114 were drilled to complete the pattern Producers 112, 113, and 114 were drilled to complete the pattern in conjunction with existing Well 84. The sides of the square pattern were 100.6 m (330 ft).

Producer and Injector Completions Producer and Injector Completions The producers were completed in 20-cm (77/8 in.) holes with 14-cm (51/2 in.) OD casing cemented in place with high-temperature cement. All were completed with slotted liners and canvas packers. Each contained 8.3-cm (2 7/8 in.) perforated tubing with a mud anchor and a high-temperature bottom-hole pump. Since the depths were shallow (Table 1), no special provisions were needed for casing expansion.

The injector was completed with 18-cm (7 in.) OD casing set to the formation top using high-temperature cement. A 15-cm (6 in.) OD hole was drilled to 0.61 m (2 ft) below the formation bottom with a 14-cm (5 1/2 in.) OD slotted liner set to this depth. Open-end injection tubing 7.6 cm (3 in.) was positioned at the bottom of the interval. No packer was used and no special provisions were made for casing expansion other than a swivel connection at the surface where the steam line joined the tubing.

Monitor Array and Completions

Twenty-nine monitor wells were positioned in concentric rings around the injector, as shown in Fig. 1. The rings were located at radii of 15.2 (50 ft), 35.0 (115 ft), 50.3 (165 ft), and 65.1 m (220 ft) from Injector 111. The wells located on these rings were on four major azimuths drawn from the injector to the producers and on four intermediate azimuths. Cored locations are indicated in Fig. 1.

JPT

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