Reservoir Study Of The Camp Sand, Haynesville Field, Louisiana
Authors: Morgan J.T. , Thompson J.E. 
Published: December 2007

A successful miscible flood was initiated during 1966 in the Camp Sand Unit, North Haynesville Field, Claiborne Parish, Louisiana. The Camp Sand Unit is about 3.5 miles (5.6 km) long and 1 mile (1.6 km) wide. Injection of a slug of enriched gas was followed by a buffer of natural gas and then by water. Over 2.4 million barrels (0.38 Mm) of oil have been recovered from the Camp Sand.

The Upper Jurassic Camp Sand occurs at a depth of 8000 ft (2438 m) and is less than 10 ft (3.05 m) thick, averaging slightly less than 5 ft (1.52 m). Vertical lithology variations indicate the sand was very likely deposited as a marine bar by a regressive sea. The expected reservoir distribution and trends of this type of deposit have been confirmed by the available reservoir data and production. Diagenesis, in the form of cementation and solution, has made minor alterations in the reservoir.

Rock characteristics, log character, and reservoir characteristics are closely interrelated. Similar rock and reservoir properties trend east-west; the same as the reservoir body. Thicker sand along the axis of the trend has the best reservoir quality; progressively poorer quality reservoir occurs toward the edge of the reservoir and with depth. Sand size and permeability decrease with depth. This layering along with horizontally oriented shells minimizes fluid cross flow or fingering by serving as baffles.

Fluids preferentially flow in the central portion of the reservoir in areas of thicker and higher quality sand. While it is estimated that waterflooding would have recovered 2 million barrels (0.318 Mm3) over a 16-year period, this project has already recovered 2.4 million barrels (0.382 Mm) of oil over a 12-year period.

Introduction

A successful miscible flood was initiated at the Camp Sand Unit during 1966. This unit is located in north Louisiana in the northern portion of the Haynesville Field (Fig. 1). The Haynesville Field was discovered in 1921 and produces from eight formations, ranging between depths of 2800 (853 m) and 11,000 ft (3353 m).

In 1961, during development of a deeper reservoir, the Smackover, oil was discovered in the Camp Sand in the area of the unit. The Upper Jurassic-aged Camp Sand occurs at a depth of 8000 ft (2438 m) and has an average pay thickness of only 4.7 ft (1.4 m). The Camp Sand's basic reservoir data are found in Table 1. Its productive area is about 3.5 miles (5.6 km) long and 1 mile (1.6 km) wide and originally contained 6.83 million STB (1.086 Mm). The initial pressure of this originally undersaturated volumetric pressure of this originally undersaturated volumetric oil reservoir was 3616 psig (24.9 MPa). Produced oil has an API gravity of 46.30 (795.8 kg/m) and a viscosity of 1.054 centipoise (0.001 054 Pa s).

Because of the Camp Sand's depth and thin pay section, working interest owners agreed to unitize the reservoir prior to development. Tenneco was elected operator and unitization became effective in February 1965. Between February 1965 and July 1966, five wells produced 132,000 barrels (20 986 m) of oil. At that time the oil's saturation pressure of 2438 psig (16.8 MPa) was reached and the wells were shut-in, pending completion of pressure maintenance facilities. The first stage of the miscible flood was implemented two months later. Injection of a slug of enriched gas was followed by a buffer of natural gas and then by water. The flood has produced over 2.4 million barrels (0.38 Mm) of oil produced over 2.4 million barrels (0.38 Mm) of oil which is 860,000 barrels (136 729 m) above the reservoir's primary recovery estimate.

METHOD OF STUDY

The study procedure used here was to accumulate data to determine the interrelationship of rock characteristics, reservoir characteristics, production characteristics, and log characteristics, and to determine reservoir trends and predict performance.

Core material from six wells was available for study.