Marathon Oil Company

Charles F Garbutt

David E Ellwood

A process is provided for treating a water to reduce its hardness by performing a series of sequential stages including a primary chemical reaction stage, a secondary chemical reaction stage and a scale removal stage. The primary chemical reaction stage includes the steps of adding a first hydroxide ion donor in the form of lime to an initial water having an initial hardness and reacting the first hydroxide ion donor to form a first portion of a scale and an intermediate water having an intermediate hardness substantially less than the initial hardness. The secondary chemical reaction stage includes the steps of adding a second hydroxide ion donor in the form of caustic to the intermediate water and reacting the second hydroxide ion donor to form a second portion of the scale and a product water having a product hardness substantially less than the intermediate hardness. The reduction contribution of the primary chemical reaction stage to total hardness reduction is substantially greater than the reduction contribution of the secondary chemical reaction stage. The scale removal stage includes the steps of separating the scale from the product water to form a sludge and disposing the sludge.

Use of multiple treatment agents to reduce hardness of an oilfield

A multi-stage process is provided for treating a water to reduce its hardness. The feed water is initially heated to a thermal reaction temperature in a heating stage. The heated water is then maintained at or near the thermal reaction temperature for a sufficient residence time to thermally react the water, producing a first portion of a scale from the scale-forming ions in the water while discharging dissolved gases from the water. After the thermal reaction stage, one or more chemical additives in the form of a hydroxide ion donor and optionally a bicarbonate ion donor are added to the heated water in a chemical reaction stage. The chemical additive is chemically reacted with the water in the chemical reaction stage, producing a second portion of the scale from the scale-forming ions in the water. A treated water having a reduced hardness is recovered from a sludge settling stage and the scale produced by the thermal and chemical reaction stages is discharged from the water and accumulated in a sludge accumulation stage for withdrawal from the process.

Water treatment process for reducing the hardness of an oilfield

A means for taking pressure readings in a bottom-hole zone of a well without interfering with an operation in which solid material is moving through a tubing string. A pressure recorder is enclosed in a carrier attached to the outer surface of a tubing sub near the end of the tubing string. The carrier walls include ports which expose the pressure recorder to the fluid in the bottom-hole zone. This arrangement allows operations such as sand fracture stimulations and rod pumping to be unimpeded by a pressure recorder.

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Midland, TX, United States of America

Charles F Garbutt