CA3021314C - Oil sands tailings ponds water disposal - Google Patents

Abstract

An oil sands tailings ponds waters process is provided where the waters from oil sands tailings ponds are aggregated and transported in a trunk pipeline for permanent deep well disposal into depleted gas reservoirs and or saline aquifers.
The process provides flexibility to dispose of oil sands process affected water, recycled cooling water, mine depressurization water, mature fine tailings, fine fluid tailings, fluid tailings, high total suspended solids water, and provides simplicity for oil sands operators.

Description

OIL SANDS TAILINGS PONDS WATER DISPOSAL
FIELD OF INVENTION
Embodiments taught herein are related to the methods and apparatus for the removal, processing, pipeline transportation and disposal of oil sands process affected tailings water (OSPW), process affected water (PAW), recycled cooling water (RCW), mine depressurization waters (MDW), mature fine tailings water (MFT), fine fluid tailings (FFT), fluid tailings (FT) and high total suspended solids water (TSS) into depleted gas reservoirs and or saline aquifers.
BACKGROUND
The Athabasca oil sands region of Alberta, Canada has world scale bitumen deposits, some of which have been producing through surface mining for over 40 years. Mining with shovel and truck, followed by crushing and slurring with water to hydro transport the bitumen to the central processing facility, followed by separation of the oil and return/ recycling of the process affected water to tailings ponds for settlement of the suspended solids is well established technology.
Oil sands process affected waters (OSPW), process affected waters (PAW), recycled cooling water (RCW), mature fine tailings water (MFT), fine fluid tailings (FFT), fluid tailings (FT) and high total suspended solids water (TSS) are a mixture of sand, water, clay and bitumen.
Approximately 1 billion m3 are currently stored in the tailings ponds located in the Athabasca region. Tailings ponds continue to grow as operators are under a zero-effluent discharge policy preventing release of accumulated process affected water. Further for every unit volume of bitumen recovered, there are 7 to 8 volume units of wet sand and MFT that need to be handled, and 10 volume units of water (recycle and make up) that are pumped around the system (Flint 2005). About 65% of the water used in the extraction process is recycled. The balance ¨ about 3 cubic metres of water per cubic metre of bitumen ¨ is trapped in the tailings pond and the pores of the sand in beaches and dykes (Flint 2005). This water is responsible for continually rising pond volumes. To reduce volumes of water stored and improve trafficability of the deposits for reclamation, these entrapped waters need to be removed with new or improved tailings treatment technologies.
I.
Date Recue/Date Received 2021-01-12 Oil sands operators are currently planning for treatment of the residual oilsands process water followed by surface discharge into end pit lakes (Water capping), wetlands or the Athabasca river.
The concern with the current plans is that the public, environmental groups and regulatory bodies have not; and likely will not into the future approve of releasing these waters back into the environment.
Since the start-up of the first mine in 1967, the oilsands operators have invested considerable time and resources into researching technology to clean up the tailings ponds and have shared their finding amongst their peers and established technical bodies.
Our search has not found any existing patents.
SUMMARY
Disclosed herein is a method for disposal of waters from bitumen extraction processes into depleted gas reservoirs and or saline aquifers, comprising the steps of:
= Pipeline transporting the waters from tailings ponds to a central pump station; and = Pipeline transporting the water from the central pump station to the gas reservoirs and/or saline aquifers.
Also disclosed herein is a system for disposal of waters from bitumen extraction processes, comprising a feed pipeline, one or more pump stations, and a trunk pipeline.
The feed pipeline is for transporting the waters from tailings ponds to the one or more pump stations.
The trunk pipeline is for transporting the waters from the one or more pump stations to depleted gas reservoirs or saline aquifers for permanent storage.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a process flow diagram illustrating the movement of waters from tailing ponds to disposal areas.

2 Date Recue/Date Received 2021-01-12 Figure 2 is a process flow diagram illustrating the movement of waters from disposal areas through the disposal facilities, disposal pipeline system and disposal wells.
DETAILED DESCRIPTION
Oil sands Process Water (OSPW) and or Process Affected Water (PAW) and or Recycled Cooling Water (RCW) and or Mine Depressurization Water (MDW) and or Mature Fine Tailings (MFT) and or Fine Fluid Tailings (FFT) and or Fluid Tailings (FT) and or High Total Suspended Solids Water (TSS) from the tailings ponds located north of Fort McMurray are aggregated and transported in a large diameter trunk pipeline to permanent disposal into depleted gas reservoirs and or saline aquifers located south and or west of Fort McMurray, Alberta, Canada.
The processes and apparatus described herein approaches the processing of tailings waters differently from existing technology, as the process provides a simple and elegant solution.
Permanent disposal of oil sands tailings pond water into depleted gas reservoirs or saline aquifers is the first of its kind in Alberta, Canada.
This process is an improvement on the current technologies for the reclamation of the oil sands ponds, as the process provides permanent and rapid removal of the waters.
Additionally, this technology can improve tailings management plans environmental performance, duration of reclamation, and may increase oil sands operators' profitability.
The following is found within Figure 1:
The process begins with pumping tailing pond waters out of existing tailings ponds or holding ponds located in the Athabasca region, Alberta (1), with centrifugal booster pumps (2), metering the water via coriolis meter technology (3), down the feed pipeline consisting of freestanding HDPE (high density polyethylene) pipeline (4) to a central pump station (6).
At the central pump station, waters may be filtered through a tank (5) with natural silica sand to lower and improve the total suspended solids (TSS) content.
The central pump station (6) and or additional pump stations (8) pump the water via positive displacement pumps (6) in a 36" outside diameter trunk pipeline internally lined with HDPE (7)

3 Date Recue/Date Received 2021-01-12 to disposal facilities located to the south of Fort McMurray. Alternatively, the same pumps (6) pump the water in a (pipe size to be determined) trunk pipeline internally lined with HDPE (13) to disposal facilities located to the west of Fort McMurray. At the end points of the trunk pipelines (7 & 13), water can be stored in atmospheric tankage (9, 10, 11 &
14).
The following is found within Figure 2:
Waters are transferred out of tankage with a centrifugal booster pumps (15), then pumped with positive displacement pumps (16), metered with turbine meters (17) and pumped down main disposal pipelines (18 & 21) to multiple well pads. At the well pads, waters are directed to multiple wells where the water is metered with turbine meters (19) and disposed into Class lb disposal wells (20), namely depleted gas reservoirs and/or saline aquifers.
The depleted gas reservoirs and/or saline aquifers may include, for example, Duncan B pool Grosmont B&C
zones, Calling Lake Nisku & Grosmont B pool zones, Atmore Nisku & Grosmont A
pool zones, and Grosmont geological formation.
An alternative embodiment to the proposed process as depicted in Figure 1, is the use of any combination or permutations of the following:
a. Vertical can, positive displacement or multistage centrifugal booster pumps b. Turbine, mag or positive displacement metering c. Steel, composite or fiberglass feed pipeline d. Multistage or slurry pumps at the pump station(s) e. Larger or smaller outside diameter trunk pipeline f. HDPE or composite trunk pipeline(s) g. Internally coated trunk pipeline(s) h. Additional, less or total elimination of storage at the injection facility(s) i. Additional, less or total elimination of water filtration (5).
A further alternative embodiment to the proposed process as depicted in Figure 2, is the use of any combination or permutations of the following:
i. Vertical can, or multistage centrifugal injection pumps ii. Coriolis, mag or positive displacement metering iii. Composite, HDPE or fiberglass injection pipeline(s) iv. Larger or smaller OD injection pipeline(s) v. Steel, internally bare injection pipeline(s)

4 Date Recue/Date Received 2021-01-12 i. Additional or less disposal well(s) ii. Additional or less disposal locations Objectives / Features:
= The deep well disposal of immense volumes of tailings waters at high rates is a new idea and it can be done commercially by utilizing depleted natural gas reservoirs and or saline aquifers.
= 70,000 m3/d capacity = Reduces or eliminated the need for oil sands operators to expand or build additional tailings ponds. No additional surface disturbance associated with tailings ponds.
= Integrated carbon capture and storage utilizing the water solution infrastructure (includes transportation pipelines and disposal systems).
Usefulness:
= Process will provide industry and government with a solution to safely and permanently remove these tailings ponds water from the environment.
= Continual recycle of process water (tailings release water) to the extraction plants has led to a build-up of dissolved ions within the recycle water. Dissolved ions of concern are salts and chlorides. Elevated ion concentrations can lead to various operational problems including poor extraction recovery, scaling/fouling and internal corrosion of piping and equipment (Beier et al. 2009) and create future environmental problems for water release and treatment. Large scale permanent disposal will alleviate this problem.
= Allows for scale up of existing tailings management technologies and solutions.
Lab / Engineering Results:
= Material balance calculations completed on Duncan B pool, within the Grosmont B&C pool gas zones indicate 58 to 91 years of disposal capacity at the 70,000 m3/d design rate.
= The process has an anticipated lifespan of 40 to 50 years, as such the engineering results show good results.
Date Recue/Date Received 2021-09-24

Claims (15)

What is claimed is:

1. A system for permanent disposal of waters from a plurality of sources created by bitumen extraction processes by injection into subterranean geological reservoirs, the system comprising:
at least one feed pipeline for transporting a disposal stream from at least one tailings pond to at least one pumping station, the at least one tailings pond containing an extractable supply of the disposal stream;
wherein each of the at least one pump stations is in fluid communication with the at least one tailings pond, at least one trunk pipeline, and a central pumping station operable to inject the disposal stream received into injection wells in communication with a plurality of subterranean geological reservoirs;
wherein the at least one pump station is operable to accept volumes from a plurality of the at least one feed pipelines in fluid communication with the at least one tailings pond;
wherein the at least one trunk pipeline transports the waters from the at least one pumping station to the central pumping station; and wherein the central pumping station is in fluid communication with the injection wells.

2. The system of claim 1, wherein the at least one tailings pond is connected to a producing bitumen deposit.

3. The system of claim 1 or 2, further comprising filtration means at the central pumping station for filtering the disposal stream to reduce total suspended solids content.

4. The system of claim 3, wherein the filtration means are adapted to filter the disposal stream through natural silica sand.

5. The system of claim 3 or 4, wherein the filtration means is in fluid communication with the at least one tailings pond and the at least one pumping station.

6. The system of claim 1, further comprising final filtration means down stream of the central pumping station in fluid communication with the at least one trunk pipeline.

7. The system of claim 1 or 6, further comprising atmospheric tankage at a plurality of the injection wells.

8. The system of claim 1, wherein a daily volume of waters to be disposed of comprises a plurality of existing tailing pond water volumes in fluid communication with the at least one tailings pond.

9. The system of claim 8, wherein the system is operable to dispose of the daily volume of waters into the injection wells.

10. A method for permanent disposal of waters from a plurality of sources created by bitumen extraction processes by injection into subterranean geological reservoirs, the method comprising:
transporting a disposal stream from at least one tailings pond containing an extractable supply of the disposal stream to at least one pumping station through at least one feed pipeline;
wherein each of the at least one pumping stations is in fluid communication with the at least one tailings pond, at least one trunk pipeline, and a central pumping station operable to inject the disposal stream;
transporting the disposal stream via the at least one trunk pipeline from the at least one pumping station to the central pumping station;
transporting the disposal stream via the at least one trunk pipeline from the central pumping station to injection wells; and receiving the disposal stream into the injection wells in communication with a plurality of subterranean geological reservoirs;
wherein the at least one feed pipeline is in communication with the at least one tailings pond;
wherein the at least one pump station is operable to accept volumes from the at least one feed pipeline in fluid communication with the at least one tailings pond; and wherein the central pumping station is in fluid communication with the injection wells.

11. The method of claim 10, wherein the at least one tailings pond is connected to a producing bitumen deposit.

12. The method of claim 10 or 1 1 , further comprising a step of filtering the disposal stream, at the central pumping station, to reduce total suspended solids content.

13. The method as of claim 12, wherein the step of filtering comprises filtering the disposal stream through natural silica sand.

14. The method of claim 10, further comprising a step of filtering the disposal stream down stream of the central pumping station.

15. The method of claim 1 0 or 1 4, further comprising a step of storing the disposal stream in atmospheric tankage at the injection wells.