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PROCESS FOR SUPPLYING VARIABLE SALINITY WATER FOR A HYDROCARBON RECOVERY PROCESS

IP.com Disclosure Number: IPCOM000248093D
Publication Date: 2016-Oct-25
Document File: 5 page(s) / 73K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention relates generally to hydrocarbon recovery and in particular to systems and processes for supplying low salinity and low sulfate water for well injection in hydrocarbon recovery processes. The methods focus on using reverse osmosis (RO) and nanofiltration (NF) membranes in a staged configuration to supply variable salinity water that is injected into a well formation, while maintaining low sulfate level and hardness. In one method the RO array is placed in the first stage and the NF array in the second stage. In a second method the NF array is placed in the first stage and the RO array in the second stage. This method is applicable in situations where the desired salinity level is in the range 500 to 27,000 mg/l of total dissolved solids. This design has the advantage of providing higher recovery over a purely parallel NF and RO design, particularly at the higher salinity levels, while meeting low sulfate levels required for the injection wells.

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PROCESS FOR SUPPLYING VARIABLE SALINITY WATER FOR A HYDROCARBON RECOVERY PROCESS

BACKGROUND

The invention relates generally to hydrocarbon recovery and in particular to systems and processes for supplying low salinity and low sulfate water for well injection in hydrocarbon recovery processes. Injecting low salinity water into a hydrocarbon bearing formation wells increases the amount of hydrocarbons recovered from the wells. However, using water with too low a salinity is detrimental to the recovery of hydrocarbons. Typical RO permeate produces water that has lower salinity than the desired level. The lower salinity can damage the hydrocarbon bearing formation and reduce hydrocarbon production from the well. For example, when the salinity of water is too low the clay formations swell, causing loss in hydrocarbon production. While the required level of water salinity could vary from 500 to 27,000 mg/l of total dissolved solids TDS, typically it is estimated to range from 1,000 to 6,000 mg/l of TDS. To increase the salinity of the permeate water, seawater could be bypassed around the RO and mixed in with the permeate. However this method has the disadvantage that the sulfate level in the water increases to a level much higher than the desired, which can vary from 10 to 100 mg/l.

There are various known processes for treatment of water used for well injection in hydrocarbon recovery process. WO2011086346A1 focuses on using reverse osmosis R O and nanofiltration NF in a parallel array. This achieves low salinity by feeding sea water to both the RO and NF. WO2013/012548A1

                                  US20120067820A1 uses any type of membranes and configuration in the process of water injection for enhancing the oil recovery.

The following problems must be faced during treatment of water using traditional methods: 1) the salinity of treated water is lower than the desired level, 2) the amount of recovered low salinity water is very low, 3) the sulfate level in the treated water is high. Methods and processes are proposed here that solve most of the above-mentioned challenges in recovering salts in an efficient and cost effective way.

BRIEF DESCRIPTION OF DRAWINGS

The invention discloses systems and processes for supplying low salinity and low sulfate water for well injection in hydrocarbon recovery process, in which:

FIG. 1 shows the layout of RO-NF equipment for producing low salinity, low sulfate water.

FIG. 2 shows the layout of NF-RO equipment for producing low salinity, low sulfate water.

operates the NF and RO systems in parallel, with appropriate NF/RO

permeate blending to achieve the desired salinity level.


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DETAILED DESCRIPTION

The invention discloses systems, methods and processes for supplying low salinity and low sulfate water for well injection in hydrocarbon recovery. The methods focus on using reverse osmosis RO) and nanofiltration NF membranes in a staged configuration to supply variable salinity water that is injected into a well forma...