H2S abatement plan during drilling operations

"In the event that an unplanned venting of geothermal steam occurs during drilling operations, a plan has been established to abate the resulting HzS emissions. If a surge of geothermal fluid occurs during drilling, a rupture disc in the blowout prevention stack will break at between 150 psi and 175 psi, allowing the steam, gas, and fluid to flow through a vent line to an atmospheric separator (Figure 1). The flow of geothermal steam, fluid, and gas will be treated by injecting an aqueous solution of sodium hydroxide into the vent line. In the event that the flow of geothermal fluid is dry steam or nearly so, additional water can be injected into the vent line using the rig pumps. In order to determine the concentration of HzS emitted to the atmosphere, discrete samples of the steam will be withdrawn from the top of the atmospheric separator and analyzed using an accurate chemical test.