The corrosiveness of Lake Maracaibo water can be greatly reduced by removing its dissolved oxygen. A packed deaeration tower for this purpose was built and operated as a part of the Santa Barbara Pilot Water Flood project. The oxygen is stripped with natural gas containing carbon dioxide. Carbon dioxide is absorbed in the process. As the carbon dioxide content of the water increases the pH decreases. Experimentally determined equations are given to show the relations between oxygen, carbon dioxide, and pH at various water throughputs and gas-water ratios.
Corrosion rates were determined on both the inlet and outlet sides of the tower. Flanged spools gave average corrosion rates over the time of the test period. Corrosometer probes were placed in different size pipe to determine the effect of water velocity.
The corrosion rates on the outlet side of the tower were only 10 to 15 percent of those on the inlet side. The outlet piping was clean whereas-the inlet piping was heavily scaled with corrosion products. Data are given to show the variation of corrosion rate with dissolved oxygen, carbon dioxide, and pH. The effect or water velocity is discussed.
It is concluded that a deaeration tower is a practical means of reducing the corrosiveness of Lake Maracaibo water.
Water flooding has long been recognized as a profitable means of increasing petroleum production. The payout can be especially attractive i those areas such as Lake Maracaibo where there is an abundant supply of water. The reservoirs in this area are large enough to take large volumes of water over long periods of time. This increases return on investment since construction and operating costs per barrel injected are less than for low volume - shortlife floods.
A factor that can markedly reduce the investment return on a long life flood is the expense due to equipment corrosion. The allowable corrosion rates in a 20 year flood are one half those of a 10 year flood. The nature or corrosion is such that the frequency of corrosion failures reaches a maximum in the later life of a flood near its economic limit. Repairs and replacements that would be economically feasible in the first 5 years of a 20-year flood become prohibitive in the last 5 years.