Page 12 - Geochemistry of Oil Field Waters

Chapter 1. INTRODUCTION

Petroleum, known to exist long before an oil well was drilled, first found
limited use as a medicine, lubricant, and waterproofing agent. The American
Indians knew of several oil and gas springs and gave this information to the
early American settlers. Early settlements were commonly located close to
salt licks which supplied salt to the population. Often these salt springs were
contaminated with petroleum, and many of the early efforts to acquire more
salt by digging wells were rewarded by finding unwanted increased amounts
of oil and gas associated with the saline waters. In the Appalachians: many
saline water springs occurred along the crests of anticlines (Rogers and
Rogers, 1843).
In 1855 it was found that distillation of petroleum produced a light oil
similar to coal oil, which was better than whale oil as an illuminant (Howell,
1934, p.2). This knowledge spurred the search for saline waters which con-
tained oil. Colonel Edward Drake, utilizing the methods of the salt pro-
ducers, drilled a well on Oil Creek, near Titusville, Pennsylvania, in 1859. He
struck oil at a depth of 21 m, and this first oil well produced about 35 barrels
of oil per day (Dickey, 1959).
The early oil producers did not realize the significance of the oil and saline
waters occurring together. In fact, it was not until 1938 that the existence of
interstitial water in oil reservoirs was generally recognized (Schilthuis, 1938).
Torrey (1966) was convinced as early as 1928 that dispersed interstitial
water existed in oil reservoirs, but his belief was rejected by his colleagues
because most of the producing oil wells did not produce any water upon
completion. Occurrences of mixtures of oil and gas with water were rec-
ognized by Griswold and Munn (1907), but they believed that there was a
definite separation of the oil and water, and that oil, gas, and water mixtures
did not occur in the sand before a well tapped the reservoir.
It was not until 1928 that the first commercial laboratory for the analysis
of rock cores was established (Torrey, 1966); the first core tested was from
the Bradford Third Sand (from the Bradford field, McKean County, Pennsyl-
vania). The percent saturation and percent porosity of this core were plotted
versus depth to construct a graphic representation of the oil and water
saturation. The soluble mineral salts that were extracted from the core led
Torrey to suspect that water was indigenous to the oil productive sand.
Shortly thereafter a test well was drilled near Custer City, Pennsylvania,
which encountered higher than average oil saturation in the lower part of the
Bradford Sand. This high oil saturation resulted from the action of an un-