Disclosed are methods and compositions for coagulating and clarifying produced waters for use as boiler feed waters, for example for the generation of steam. The methods and compositions are especially useful for treatment of produced waters from steam-injection methods of tertiary oil recovery such as steam-assisted gravitational drainage. Disclosed are compositions comprising a first copolymer having a high molecular weight and bearing a low molar cationic charge and a second copolymer having a lower molecular weight and bearing a high molar cationic charge. The compositions are suitable for addition as coagulants to produced waters that have been treated by warm lime softening. Also disclosed are methods of treating produced waters from steam-injection oil recovery for use as boiler feed waters to generate steam in such steam injection methods.

Disclosed are methods and compositions for coagulating and clarifying produced waters for use as boiler feed waters, for example for the generation of steam. The methods and compositions are especially useful for treatment of produced waters from steam-injection methods of tertiary oil recovery such as steam-assisted gravitational drainage. Disclosed are compositions comprising a first copolymer having a high molecular weight and bearing a low molar cationic charge and a second copolymer having a lower molecular weight and bearing a high molar cationic charge. The compositions are suitable for addition as coagulants to produced waters that have been treated by warm lime softening. Also disclosed are methods of treating produced waters from steam-injection oil recovery for use as boiler feed waters to generate steam in such steam injection methods.

Produced water from a crude oil or natural gas production process is purified using a membrane purification system for petroleum production, agricultural, commercial and domestic uses. The produced water is pretreated to remove, at least, particulates and oil from the produced water. The minimally pretreated water is then purified in a membrane purification system, that is operated at conditions such that membrane scaling is reduced or prevented. In particular, the membrane purification system is operated to maintain the turbidity of clarified water feed to the system or intermediate aqueous streams that are cascading through the membrane purification system. Ensuring that the turbidity of the reject streams generated in the membrane system are useful in achieving long membrane operating life.

Produced water from a crude oil or natural gas production process is purified using a membrane purification system for petroleum production, agricultural, commercial and domestic uses. The produced water is pretreated to remove, at least, particulates and oil from the produced water. The minimally pretreated water is then purified in a membrane purification system, that is operated at conditions such that membrane scaling is reduced or prevented. In particular, the membrane purification system is operated to maintain the turbidity of clarified water feed to the system or intermediate aqueous streams that are cascading through the membrane purification system. Ensuring that the turbidity of the reject streams generated in the membrane system are useful in achieving long membrane operating life.

An ion removal system includes: an ion removal device including a hard water storage configured to store hard water and a fine bubble generator configured to generate a fine bubble to supply the hard water storage with the fine bubble, for removing a metal ion from the hard water by adsorbing the metal ion in the hard water to the fines bubble in the hard water storage and crystallizing and precipitating the adsorbed metal ion; and a particle feeder configured to bring a particle containing a same element as that of the metal ion into the hard water at a feeding point, the feeding point being located upstream of the hard water storage or located in the hard water storage.

An ion removal system includes: an ion removal device including a hard water storage configured to store hard water and a fine bubble generator configured to generate a fine bubble to supply the hard water storage with the fine bubble, for removing a metal ion from the hard water by adsorbing the metal ion in the hard water to the fines bubble in the hard water storage and crystallizing and precipitating the adsorbed metal ion; and a particle feeder configured to bring a particle containing a same element as that of the metal ion into the hard water at a feeding point, the feeding point being located upstream of the hard water storage or located in the hard water storage.

An oil or gas recovery process (10) is disclosed where resulting produced water includes silica. The process entails removing silica from the produced water via a two-stage process. In the first stage, magnesium oxide is injected into a Magnesium Dissolution Reactor (18) and mixed with the produced water to dissolve magnesium. Effluent from the Magnesium Dissolution Reactor (18) is directed downstream to a warm lime softener (22) where one or more alkaline chemicals are added to the produced water to raise the pH to approximately 10.0 to 11.5. Here, silica is co-precipitated with magnesium hydroxide and/or adsorbed onto magnesium hydroxide precipitates.

An oil or gas recovery process (10) is disclosed where resulting produced water includes silica. The process entails removing silica from the produced water via a two-stage process. In the first stage, magnesium oxide is injected into a Magnesium Dissolution Reactor (18) and mixed with the produced water to dissolve magnesium. Effluent from the Magnesium Dissolution Reactor (18) is directed downstream to a warm lime softener (22) where one or more alkaline chemicals are added to the produced water to raise the pH to approximately 10.0 to 11.5. Here, silica is co-precipitated with magnesium hydroxide and/or adsorbed onto magnesium hydroxide precipitates.

A hardness reduction filter is provided. The hardness reduction filter may include a filter housing having a space formed therein, a filter provided in the space of the filter housing to filter out foreign materials from water flowing into the filter housing, and hardness reduction catalysts provided between the filter housing and the filter and configured to perform at least one of removing a hard water material contained in the water or preventing formation of a scale inducing material in the water flowing into the filter housing.

A hardness reduction filter is provided. The hardness reduction filter may include a filter housing having a space formed therein, a filter provided in the space of the filter housing to filter out foreign materials from water flowing into the filter housing, and hardness reduction catalysts provided between the filter housing and the filter and configured to perform at least one of removing a hard water material contained in the water or preventing formation of a scale inducing material in the water flowing into the filter housing.