CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Pat. App. No. 62/637,122 incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention generally relates to management of drilling wastes and more particularly, relates to methods and systems of recycling and treating waste water generated by drilling activities.

BACKGROUND OF THE INVENTION

[0003] Effective drilling waste management represents an important consideration when expanding oil and gas exploration into environmentally sensitive areas. Nonetheless, approaches to waste management include minimizing the volume and toxic fraction of wastes generated from wet drill cuttings and other drilling wastes such as oily waste water and drilling muds. However, current approaches fail to segregate containments and/or manage each containment efficiently.

[0004] Generally, wet drill cuttings may comprise about 20 percent oil, about 50 percent water and about 30 percent solids. As much as 500 to 1000 cubic meters of waste water may need processing during the duration of drilling. Further, different factors have a direct impact on increasing the processing volumes. In drilling operations, waste water is generated from the drilling operation on the rig floor, rig wash down activities, rig tank cleaning and the solids control equipment (solids control centrifuges, waste management centrifuge, mud cleaner, desilter and desander). However, excess water usage, improper handling of surface losses, mud tank cleaning, use of inappropriate tools in cleaning operations, and poor conditions of drilling equipment and solids control, each can represent an important waste water stream that increases the amount of waste water processing. Furthermore, waste water charged with contaminated solids and/or drilling muds cannot be treated by simple settling tanks alone. At the end of drilling, complex cuttings with high liquid contact are difficult to treat using solidification and/or thermal technologies.

[0005] A need exists, therefore, for methods and systems that can efficiently optimize processing volumes and segregate drilling waste materials and dry drill cuttings, in a cost-effective manner, while recovering drilling fluids, oil, recycling treated waste water, and disposing cuttings generated from mud separation processes.

SUMMARY OF THE INVENTION

[0006] Provided herein are integrated chemical flocculation and dewatering systems comprising a flexible dewatering container, a waste unit, a chemical dosing unit and a mixing tank. The flexible dewatering container is in fluidic communication with a waste unit. The waste unit is configured to maintain oily waste water. The chemical dosing unit is in fluidic communication with the flexible dewatering container. The chemical dosing unit is configured to maintain chemical flocculants. The mixing tank is in fluidic communication with the chemical dosing unit. The mixing tank is connected to the flexible dewatering container to create a fluidic pathway of treated oily waste water between the mixing tank and the flexible dewatering container. The flexible dewatering container is configured to separate and dry solids from oily waste water creating a fluidic pathway of oil and water discharging from the dewatering container.

[0007] In an aspect, the integrated chemical flocculation and dewatering systems further comprise a settling tank having a clean water outlet. The settling tank is in fluidic communication with the flexible dewatering container. In an aspect, integrated chemical flocculation and dewatering systems further comprise a water pump configured to draw liquid from the flexible dewatering container and discharge liquid into the settling tank. The water pump can be connected to the settling tank creating a fluidic pathway of clean water from the flexible dewatering container to the clean water outlet of the settling tank. In an aspect, the integrated chemical flocculation and dewatering systems comprise a disposal unit connected to the settling tank. In an aspect, the integrated chemical flocculation and dewatering systems comprise a sulfuric acid tank connected to the mixing tank. In an aspect, the integrated chemical flocculation and dewatering systems comprise a centrifugal pump configured to draw oily waste water from the waste unit and discharge oily waste water into the mixing tank. Also provided are integrated chemical flocculation and dewatering systems for drying solids from oily waste water generated during oil and gas production, particularly drilling operations. These systems include a flexible dewatering container, a waste unit, a settling tank, a mixing tank and a chemical dosing tank. The flexible dewatering container is in fluidic communication with a waste unit and a settling tank. The waste unit is configured to maintain oily waste water and the settling tank having a clean water outlet. The chemical dosing unit is in fluidic communication with the flexible dewatering container. The mixing tank is in fluidic communication with the chemical dosing unit and connected to the flexible dewatering container creating a fluidic pathway of treated oily waste water between the mixing tank and the flexible dewatering container. The flexible dewatering container is configured to dry solids from oily waste water and generate a fluidic pathway of liquid between the dewatering container and the outlet of the settling tank. In an aspect, the integrated chemical flocculation and dewatering system further comprises a sulfuric acid tank connected to the mixing tank. In an aspect, the integrated chemical flocculation and dewatering system further comprises a centrifugal pump. The centrifugal pump draws oily waste water from the waste unit and discharges oily waste water into the mixing tank.

[0008] In an aspect, the integrated systems can utilize a plurality of flexible dewatering containers. In an aspect, the integrated chemical flocculation and dewatering system includes a water pump configured to draw liquid from the flexible dewatering container and discharge water from the system through the clean water outlet of the settling tank. In an aspect, the integrated chemical flocculation and dewatering system includes a screw pump is connected to flexible dewatering container and the mixing tank. The screw pump is configured to move treated oily waste water from the mixing tank into the flexible dewatering container.

[0009] Further provided herein are methods of recovering clean oil and water from oily waste water comprising the steps of: providing oily waste water; mixing oily waste water with sulfuric acid and one or more chemical flocculants to form treated oily waste water comprising solids; and drying solids from the treated waste water in a flexible dewatering container. Oily waste water permeates through the flexible dewatering container to form a recoverable liquid. In an aspect, recoverable liquid comprises water and/or oil. In an aspect, the present methods can further comprise the step of separating water from the recoverable liquid. In an aspect, the present methods further comprise the step of recycling water to a drilling or refining operation in an aspect, the methods further comprise the step of separating clean oil from the recovered liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Fig. 1 is a photograph showing a setup of a flexible dewatering container as described herein.

[0011] Figs. 2A, 2B, and 2C shows generally how the flexible dewatering container can work in connection with the systems provided herein. Specifically, Fig. 2A shows the flexible dewatering container as a containment vessel. Fig. 2B depicts the flexible dewatering container as excess water drains from the flexible dewatering container providing efficient volume reduction of waste materials. Fig. 2C shows the flexible dewatering container in a final cycle of filling and dewatering.

[0012] Fig. 3 is a photograph showing an empty waste pit designed to stock liquid gas solids and other wastes generated during a drilling operation.

[0013] Fig. 4 is a photograph showing the flexible dewatering container filled with solids from the drilling waste materials.

[0014] Fig. 5 is a schematic drawing the flexible dewatering container filled with solids from the drilling waste materials.

[0015] Fig. 6 is a photograph showing a set-up of a dewatering system as described herein. [0016] Fig. 7 is a flow diagram of processing of oily drilling slop wastes.

[0017] Fig. 8 is a diagram depicting systems of water recovery and treatment described herein.

[0018] Fig. 9 is a photograph of two flexible water containers used to manage waste materials from drilling muds.

[0019] Fig. 10 is a chart of the total water used from rig tank, well and fluids section of four wells.

[0020] Fig. 11 is a chart of the total used and retrieved water from four wells.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] As used herein, the terms“a” and“the” as used herein are understood to encompass the plural as well as the singular.

[0022] The terms“oily waste water,”“oily waste” and“waste” are used interchangeably and refer to drilling waste materials and other liquid wastes from drilling, production or refining activities. Oily waste water can occur from rig drains, tank cleaning, washdown water spills and the like. Waste can be a mix of oil, drilling muds, solids and water. Sometimes oily waste water is referred in the industry as drilling slop.

[0023] As used herein, the term“solids” refers to drilling cuttings generated during the drilling process from the geological formations in the well bore being drilled, drilling fluids, and other components associated from various type of wastes including but not limited to, waste lubricant, spacers, water based muds, oil based muds, spent bulk chemical (cement, bentonite, barites, viscosities, thinners, fluid loss reducers), specialty product (H2S scavengers, defoamers, tracers).

[0024] As used herein, the term“chemical flocculants” include but are not limited to aluminum coagulants including aluminum sulfate, aluminum chloride and sodium aluminate; iron coagulants including ferric sulfate, ferrous sulfate, ferric chloride and ferric chloride sulfate and other chemicals used as coagulants such as hydrated lime and magnesium carbonate.

[0025] As used herein, the term“specialty polymers” means chemicals used for flocculating solids.

[0026] Provided herein are integrated chemical flocculation and dewatering systems 10 useful in drying solids from oily waste water and from other waste. These systems 10 include a flexible dewatering container 22 that can be filled with fine grain sludge, hazardous contaminated soils, or dredged waste materials.

[0027] In addition to the flexible dewatering container 22, the integrated chemical flocculation and dewatering systems 10 comprise a waste unit 26, a chemical dosing unit 18 and a mixing tank 20. The flexible dewatering container 22 is in fluidic communication with a waste unit 26. The waste unit is configured to maintain oily waste water. The chemical dosing unit 18 is in fluidic communication with the flexible dewatering container 22. The mixing tank 20 is in fluidic communication with the chemical dosing unit 18. The mixing tank 20 is connected to the flexible dewatering container 22 to create a fluidic pathway of treated oily waste water between the mixing tank and the flexible dewatering container 22. The chemical dosing unit 18 is configured to maintain chemical flocculant. As described herein, the flexible dewatering container 22 is configured to dry solids from oily waste water. The flexible dewatering container 22 generates a fluidic pathway of oil and water discharging from the dewatering container. This liquid (oil and water) can later be separated to produce a recyclable water. Dried solids remain in the flexible dewatering container 22 for disposal or can be discharged from the flexible dewatering container and disposed into another tank or vessel (not shown).

[0028] The flexible dewatering container 22 provides versatile containment for dewatering of oily waste water. The flexible dewatering containers 22 are fabricated with special high strength geotextile and are cost effective in filtration applications. High strength permeable geotextiles provide certain retention properties for filling the flexible dewatering containers with fine grain sludge and/or hazardous contaminated soils, allowing liquid to flow out of the container while solids remain inside. The retention properties are based on particle size of the solids and permeability of the geotextile. The size of the flexible dewatering container can be manufactured to suit the project requirements. The size of the flexible dewatering container includes ranges of circumference of the container 22 from about 2.3 meters to about 27.4 meters and lengths from about 30 meters to about 60 meters. In addition, the flexible dewatering containers can have capacities of up to 300 cubic meters waste volume storage. The flexible dewatering container 20 can be fabricated with various seaming techniques so to withstand pressure during pumping operations. The flexible dewatering container 20 can even be mounted in mobile roll-off containers and transported as necessary. The flexible dewatering container 20 is supplied to rig site and placed into position.

[0029] Oily waste water in the form of sludge can be treated with sulfuric acid, flocculants and other chemicals and then pumped into the flexible dewatering container. Liquid, predominantly water and oil, drains from the flexible dewatering container 20 leaving solids within the flexible dewatering container. When full, the flexible dewatering container can be disposed at a landfill or the solids removed and land-applied.

[0030] The flexible dewatering container allows residual materials to dewater and can contain solids at a flow rate of between about 0 to about 100 cubic meters per hour. Through small pores in the fabric/textile of the flexible dewatering container, liquid (an oil and water mix) drains from the flexible dewatering container resulting in effective dewatering and efficient volume reduction of the contained materials. V olume reduction of solids allows for the repeated filling of the flexible dewatering container. Solids are captured, and liquid can be collected, and oil and water separated. Water recirculated through the system 10.

[0031] After final cycle of filling and dewatering, the solids remain in the flexible dewatering container 22 and continue to density due to desiccation as residual water vapor escapes through the fabric. The process can be cycled on a batch basis so that each batch processed is a cycle or the process can be a continuous process. Volume reduction of wastes can be as high as 90%. When full, the flexible dewatering container 22 and its contents can be deposited at a landfill, remain on-site, or the solids can be removed and land-applied when appropriate.

[0032] Oily waste water in the form of a sludge (or a slurry material) can be pumped into the flexible dewatering container 22. Environmentally-safe polymers can be added to the oily waste water to facilitate solids binding together and water and oil separating. The flexible dewatering container 22 is made of geotextile fabric designed to confine fine grains of solids such as high strength polypropylene geotextiles.

[0033] More specifically, effluent water can drain from the container 22 through small pores in the engineered textile fabric. Effective dewatering and efficient volume reduction of waste materials is achieved. The volume reduction allows for repeated filling of the flexible dewatering container. As much as 99% of solids can be captured, and clear filtrate (liquid) can be collected and oil separated from water and water recirculated through the system 10. The decanted water separated from the liquid (filtrate) can be reused/retumed for processing or returned to native waterways without additional treatment.

[0034] As described herein the flexible dewatering container 22 can be filled with oily waste water in the form of a sludge slurry and having high concentration of water and oil. Figs. 2A, 2B & 2C. Water filters through the walls of the flexible dewatering container and the solids remain trapped inside the container 22. This methodology reduces the amount of liquid materials to be disposed and provides solids (solid waste) which are easily handled and can be treated using known methods including but not limited to thermal desorption, bioremediation, stabilization and fixation. Other methods of disposal include onsite burial, land farming and incineration, deep-well injection and vermiculture.

[0035] As shown in Figs. 7 and 8, in an aspect, integrated chemical flocculation and dewatering systems 10 further comprise a settling tank 24 having a clean water outlet 28. The settling tank 24 is in fluidic communication with the flexible dewatering container 22. In an aspect, integrated chemical flocculation and dewatering systems 10 further comprises a water pump 46 configured to draw liquid from the flexible dewatering container 22 and discharge liquid into the settling tank 24. The liquid can contain both oil and water or water alone or oil alone. The water pump can be connected to the settling tank 24 creating a fluidic pathway of clean water from the flexible dewatering container to the clean water outlet 29 of the settling tank 24.

[0036] As further shown in Figs. 7 and 8, the integrated chemical flocculation and dewatering systems 10 has a disposal unit 26 connected to the settling tank 24. In an aspect, the integrated chemical flocculation and dewatering systems 10 further comprise a sulfuric acid tank 16 connected to the mixing tank 20. In an aspect, the integrated chemical flocculation and dewatering systems 10 include a centrifugal pump 12 configured to draw oily waste water from the waste unit 26 and discharge oily waste water into the mixing tank 20. As shown in Fig. 9, the system can utilize a plurality of flexible dewatering containers 22.

[0037] In the containment stage, the durable and high retention fabric allows water and oil to separate and form a dense monolithic structure. In a final step, the contained and densified solids can be a structural mass. After the final cycle of filling and dewatering, the solids remain in the bag and continue to density due to desiccation as residual water vapor escapes through the fabric. Volume reduction can be as high as 90 percent. When full as shown in Figs. 4 and 9, the flexible dewatering container 22 and contents can be deposited at a landfill, remain on-site, or the solids can be removed and land-applied when appropriate.

[0038] In an aspect, the flexible dewatering container 22 can be a GEOTUBE® container sold by Tenecate and constructed of a unique fabric, specially engineered for a marine structure. In an aspect, the flexible dewatering container is a GEOTUBE® Type W-PP80 THF, having dimensions of 20 meters by 3 meters by .8 meters.

[0039] As shown in Fig. 8, waste injected into the flexible dewatering container 22 can be performed via a screw pump 48 with low speed where the flocculation is controlled simultaneously. When pumping, a coil of 20 meters in length is used just after the pump circulation system to guarantee the good flocculation of the solids, and then the solids are trapped in the flexible dewatering container allowing the liquid (oil and water) to discharge from the flexible dewatering container. The liquid (oil and water) coming out from the flexible dewatering container 22 can be collected via a diaphragm pump (not shown) to a skimmer tank (not shown) for further mechanical separation. The flexible dewatering container 22 is continuously filled until the flexible dewatering container 22 is plugged or when the geotextile membrane gets blocked by solid particles and liquid can no longer permeate the container. Then the flexible dewatering container 22 has to be changed and needs to be replaced. The pH of the water out of the flexible dewatering container 22 is corrected if required before to be sent to a settling tank to ensure that remaining floating oil is removed. After a final cycle of filling and dewatering, the retained fine grain materials can continue to consolidate by evaporation as the residual water vapor escapes through the geotextile. Clean water out of the flexible dewatering container 22 can be sent back to the settling tank for further treatment. The solids retained inside the flexible dewatering container 22 will be transferred to solidification unit (not shown) for treatment.

[0040] The integrated chemical flocculation and dewatering system 10 can include a water pump 46 configured to draw liquid from the flexible dewatering container 22 and discharge water from the system 10 through the clean water outlet of the settling tank. The integrated chemical flocculation and dewatering system 10 can further include a screw pump 48 connected to flexible dewatering container and the mixing tank. The screw pump 48 can be configured to move treated oily waste water from the mixing tank 20 into the flexible dewatering container 22. In an aspect, the integrated chemical flocculation and dewatering system 10 further comprises a centrifugal pump 12. The centrifugal pump 12 draws oily waste water from the waste unit and discharges oily waste water into the mixing tank 20.

[0041] As shown by way of example below, the present methods of recovering clean oil and water from oily waste water comprising the steps of: providing oily waste water; mixing oily waste water with sulfuric acid and one or more chemical flocculants to form treated oily waste water comprising solids; and drying solids from the treated waste water in a flexible dewatering container 22. Oily waste water permeates through the flexible dewatering container 22 to form a recoverable liquid. In an aspect, recoverable liquid comprises water and/or oil. In an aspect, the present methods can further comprise the step of separating water from the recoverable liquid. In an aspect, the present methods further comprise the step of recycling water to a drilling or refining operation. In an aspect, the methods further comprise the step of separating clean oil from the recoverable liquid.

EXAMPLE I

Integrated Chemical Flocculation and Dewatering System Implementation

[0042] Solutions for optimizing volumes and segregating waste were explored. Using the integrated chemical flocculation and dewatering system provided herein, drill cuttings were dried and precious drilling metals recovered. Recycling and treatment of waste water generated by drilling activity were performed by the present systems. Treatments for residual cuttings generated from mud separation process were performed.

Water Consumption at the Rig Site Reduced

[0043] As shown in Figs. 1, 3, 4, 6, and 9 an integrated chemical flocculation and dewatering system 10 was used at a rig site (Well D) and compared to previous wells drilled in the same area.

Generally, 37 percent (37%) of the total water consumption at a rig site is used in the water-based mud (“WBM”) section. As shown in Tables 1A and 1B below and depicted in Figs. 9 and 10, the water consumption at the rig site (Well D) was reduced by 34 percent (34%) compared to the average water consumption of the three previous wells, Well A, Well B and Well C.

Table 1A

Table 1B

Decrease of 40 Percent of Waste Volume Requiring Offline Treatment

[0044] As shown in Fig. 6, the present system 10 was used to handle waste water generated from cleaning and cooling operations. As shown in Fig. 5, an isolated collection tank 14 was used to collect the liquid generated from solids control and waste management centrifuge 12 and a suitable concentration of flocculant was determined. Table 2 below provides an example of chemical flocculant and sulfuric acid amounts having an effective cost.

Table 2

[0045] After preparing chemical treatments, waste (oily waste water) was transferred to the collection tank from a coral pit using the backhoe. The waste was then transferred from the collection tank to the mixing unit for pH adjustment. A special acid pump (not shown) with a dosing system was installed to ensure that the appropriate amount of acid was provided. The mixing tank 20 ran for about 10 minutes. The waste was injected into the flexible dewatering container 22 having a desired quantity of flocculant also injected with the screw pump 48. In this case, recovered liquid (oil and water) that permeated from the flexible dewatering container 22 was collected via a diaphragm pump (not shown) to a skimmer tank (not shown) for further separation.

Oil Based Mud 12 ¼ inch Section

[0046] Table 3 below provides data recorded while drilling a 12 ¼ inch section.

Table 3

[0047] There was no impact to the drilling operations. Twenty-one cubic meters of homogenous water was collected from the coral pit (60% oil/water, 40% solids) and injected into the flexible dewatering container. Recovered volume of water was six cubic meters and .3 cubic meters of oil was recovered.

Oil Based Mud 8 ½ inch Section

[0048] Table 4 below present data recorded while drilling the 8 ½ inch section.

Table 4

[0049] There was no impact on the drilling operations during this section. Thirty-three cubic meters of homogenous water was collected from the coral pit (60% oil/water, 40% solids) and injected into the flexible dewatering container. The recovered volume of water was twenty cubic meters and .44 cubic meters of oil was recovered.

[0050] Table 5 below represents the results of using the flexible dewatering container to separate solids, oil and water from wastes. Table 5

[0051] In summary, fifty-six (56) cubic meters of homogenous water was collected from the coral pit (60% oil/water, 40% solids) and injected into the flexible dewatering container. The recovered volume of water was twenty-six (26) cubic meters and .74 cubic meters of oil was recovered. Wastes collected from the coral pit from cleaning equipment was segregated and handled by the present system with 46.4 % of liquid recovered from the total handled.