Method and composition for scavenging sulphide in drilling fluids
OwnerEric Davidsoninventor
Life of this patent
Estimating the term…
Abstract
An environmentally friendly method and composition is provided for removing hydrogen sulphide from fluids at high pH. The method and composition are particularly suited for removing hydrogen sulphide from drilling fluids used in drilling boreholes in hydrocarbon bearing subterranean formations, and are suitable for use with any drilling fluid, including polymer based drilling fluids. The sulphide scavenger used in the method and composition is a ferrous gluconate, an organic iron chelating agent stable at pH as high as 11.5, the pH preferred for drilling fluids that may encounter hydrogen sulphide. Further, this additive has been found to enhance the resilience of the rheological properties of drilling fluids to hot rolling and comparable field conditions.
Claims16
A drilling fluid additive comprising an iron (II) based hydrogen sulphide scavenger chelated with a gluconate chelating agent which provides a stable complex with said iron at pH greater than about 9.
In combination with a drilling mud comprising crosslinkable polymers delivered to a well during drilling operations, an additive for decreasing hydrogen sulphide concentration in the mud, the additive comprising an effective amount of a ferrous chelating agent mixed into the mud to reduce hydrogen sulphide concentration in the mud circulating in the well, wherein such additive fails to significantly cause crosslinking of said polymers.
A polymer based drilling fluid comprising ferrous gluconate.
A method of drilling a borehole in a subterranean formation containing hydrogen sulphide, said method comprising employing a polymer based drilling fluid having a pH greater than 9.0 and adding to the drilling fluid a quantity of ferrous gluconate sufficient to react with hydrogen sulphide entering said fluid from said formation such that sulphide is precipitated.
A method of drilling a borehole employing a polymer based drilling fluid having a pH greater than 9, said method comprising adding to the drilling fluid an additive comprising an iron (II) based hydrogen sulphide scavenger chelated with a gluconate chelating agent which provides a stable complex with said iron at said pH greater than 9.
Dependencies are inferred from the claim text.