Pretreatment of high salinity produced water for membrane based desalination
AssigneesSaudi Arabian Oil Company, Global Water Practice, A Division of Narasimhan Consulting Services, Inc. Dba Ncs Engineers
InventorsHasan Al Abdulgader, Young Chul Choi, Joon H. Min, Duaa J. Al Saeed
Life of this patent
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Abstract
The technology relates to the pretreatment process of a high salinity produced water stream in a gas oil separation plant (GOSP). The produced water stream includes a salinity of up to 150,000 ppm of total dissolved solids (TDS). The treated produced water stream is processed by a desalination unit integrated in the GOSP, to produce a permeate stream with less than 5000 ppm of TDS and a reject stream. The permeate stream is reused as a wash water stream in the desalter unit of the GOSP, to desalt the crude oil or use it for other beneficial reuse purposes.
Claims20
A method comprising:
- receiving, by a water oil separator in a gas oil separation plant (GOSP), a mixture of crude oil and water;
- separating, by the water oil separator, the mixture into a recovered oil stream and a produced water stream having salinity;
- flowing a first portion of the produced water stream to an injection well;
- flowing a second portion of the produced water stream to a pretreatment unit integrated in the GOSP;
- treating, by the pretreatment unit, the second portion of the produced water stream to reduce a free and emulsified oil content, an organic content, a dissolved gas, and a total suspended solids, resulting in a pretreated produced water stream;
- receiving, by the desalination unit, the pretreated produced water stream, wherein the desalination unit comprises a reverse osmosis (RO) or ultra-high pressure reverse osmosis (UHP-RO) membrane;
- wherein the desalination reduces the total dissolved solids (TDS) to produce a permeate stream and a reject stream,
- flowing the permeate stream from the desalination unit as a wash water stream to a desalter unit in the GOSP to desalt the crude oil.
A pretreatment system for a produced water stream in a gas oil separation plant (GOSP) comprising:
- a sequence of units:
- a hydroclone to remove large oil droplets and total suspended solids (TSS);
- a nutshell filter to remove small oil droplets and remaining TSS;
- a H2S gas stripper to remove dissolved sulfur containing compounds and volatile organic compounds (VOCs);
- an adsorption media to remove dissolved organics and total petroleum hydrocarbons (TPH);
- a pellet softener to remove hardness to avoid scaling;
- an automatic filter to remove fine colloidal particles;
- a ceramic ultra filtration membrane to remove dissolved oil and remaining TSS;
- a cooling system comprising heat exchangers or an evaporative cooling tower to bring down the temperature of the produced water stream;
- a sampling unit to check if the produced water stream meets a pre-determined produced water quality;
- a desalination unit placed downstream comprising a ultra-high pressure reverse osmosis (UHP-RO) membrane or reverse osmosis membrane (RO) to remove the total dissolved ions, wherein after desalination a permeate stream and a reject stream is formed;
- and
- a wash water unit installed downstream of the desalination unit, which receives the permeate stream to be used as a wash water stream to desalt crude oil.
A method to treat a produced water stream comprising:
- flowing the produced water stream to a pretreatment unit integrated in the gas oil separation plant (GOSP), further comprising:
- removing large oil droplets and total suspended solids (TSS);
- after removing large oil droplets and TSS, removing small oil droplets and remaining TSS;
- after removing small oil droplets, removing dissolved H2S and volatile organic compounds (VOCs);
- after removing dissolved H2S and VOCs, removing dissolved organics;
- after removing dissolved organics, removing hardness;
- after removing hardness, removing fine colloidal particles;
- after removing fine colloidal particles, cooling the produced water stream;
- after cooling the produced water stream, removing dissolved oil and remaining TSS;
- receiving a pretreated produced water stream by a desalination unit comprising a reverse osmosis (RO) or an ultra-high pressure reverse osmosis (UHP-RO) membrane to remove total dissolved solids (TDS), wherein the RO or UHP-RO produces a permeate stream and a reject stream;
- and
- flowing the permeate stream from the desalination unit as a wash water stream to a desalter unit in the GOSP to desalt crude oil.
Dependencies are inferred from the claim text.