CA1124091A

CA1124091A - Oilfield disposal process

Info

Publication number: CA1124091A
Application number: CA361,506A
Authority: CA
Inventors: Frank Janishewski
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-10-03
Filing date: 1980-10-03
Publication date: 1982-05-25

Abstract

ABSTRACT OF THE DISCLOSURE
A process for on-site disposal of well site sump liquid after completion of drilling at the site. Surface soil at the well site is loosened and piled into windrows.
A trench is excavated adjacent to the windrows. The windrows are sprayed periodically with part of the sump liquid so as to maintain them at least partially saturated, while allowing for evaporation. A further portion of the sump liquid is pumped into the trench, and both the dirt previously excavated from the trench and the windrows are pushed or otherwise directed into the trench.

Description

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This invention relates to a drill site waste disposal process. More specifically, it relates to a process for disposing of well site sump liquid, involving excavation of soil, admixture of such liquid with the excavated soil, and burial of the mixture in the excavation.
Typically, well sites have a small open pit, close to the well bore location, in which is maintained a liquid utilized in the drilling process. Liquid from the sump pit is used for such purposes as cooling wellhead machinery and lubricating drilling equipment. Due to such use and the proximity of the sump to the well bore, water placed in the sump pit becomes contaminated with oil, dirt and other material.
Upon termination of the drilling phase, a pad is constructed around the wellhead and the well site returned as closely as possible to its condition prior to the drilling operation.
Disposal of sump liquids presents a problem in the clean up of a well site. The difficulties involved in removing sump liquid from a drill site are obvious. The difficulties include finding an alternate site for the liquid and transporting it to that site, as well as the costs involved in such an operation. It would be preferable to dispose of the sump liquid at the drill site in such a way as to result in no permanent damage to the environment and no impediment to continued access to the immediate vicinity of the wellhead.
U.S. Patent No. 3,732,697, granted to R.S. Dickson on May 15, 1973, relates to a waste disposal method and facility. This patent teaches that disposal of large quantities of industrial liquid waste is possible in metropolitan areas by mixing such waste with sufficient loose earth to absorb it completely and placing the resulting mixture on the surface of a disposal site where it is compacted ~.2~

into successive layers. This patent also teaches that a disposal facility may be created by excavating into natural soïl and placing an artificial liner against the sloping walls of the excavation. A mixture of industrial liquid waste and soil is then placed into the lined excavation.
The waste disposal method disclosed in the Dickson patent could be applied to the liquid in a well site sump pit.
However, unlike industrial liquid wastes to which the Dickson patent is directed, well site sump liquid contains very little material that would filter through soil to contaminate underground water. If precautions are taken to limit the process of this invention to excavation of soil and not to excavation of gravel and other porous material, the sump liquid disposal process of the subject invention would provide the same safeguards against contamination as the Dickson process, but additionally~could be more rapidly and economically employed.
U.S. Patent No. 3,978,673, granted to Stephen C.
Schleede on September 7, 1976, relates to a method of disposing of liquid waste. Unlike the Dickson patent which deals with the disposal of liquid wastes from industry, the process of the Schleede patent is directed towards disposal of liquid wastes more compatible with soil, such as sewage sludge, water treatment waste, mining waste, and liquid agricultural waste. The disposal process of the Schleede patent involves continuous excavation of soil to a substantial depth in one region, and transportation and deposition of the excavated soil to a region in close proximity, whereafter liquid waste is spread onto the deposited soil while such soil is still in a permeable condition. Excavation and deposition are conducted on the opposite sides of a large trench, resulting in tillage of a large tract of land as the trench moves laterally there-across. After the soil has been transported and deposited, its permeability is considerably increased. Since the depth of excavation may extend up to 30 feet if favourable soil conditions are met, a considerable volume of permeable soil is available. The patent identifies several special types of wheel excavator which may be employed in this process.
One form of the well site sump liquid disposal process of the subject invention comprises the steps of firstly loosening surface soil at the well site and piling the loosened soil into windrows. A further step in the process involves excavating a trench adjacent to the windrows. Next, the windrows are periodically sprayed with part of the sump liquid so as to maintain saturation thereof while allowing evaporation therefrom. ~ further portion of the sump liquid is then pumped into the trench, and dirt, previously excavated from the trench, and the windrows are pushed or otherwise directed into the trench. In a further form of the process, the further portion of the sump liquid is pumped into the trench and dirt previously excavated therefrom is pushed or otherwise directed into the ditch until the resultant mud mixture fills a substantial part of the trench. Then the windrows are pushed or otherwise directed into the trench. In a further form of the process, the sump liquid is pumped into the trench with simultaneous pushing or otherwise directing of dirt thereinto. A still further form of the process comprises the additional steps of piling some of the loosened dirt into additional windrows adjacent to the sump liquid pit, spraying the additional windrows periodically with part of the sump liquid, and pushing or otherwise directing the additional windrows into the sump liquid pit after the remainder of the sump liquid has been pumped from that pit. In a yet further form of the invention, part of the excavated dirt is directed into the pit from which the sump liquid has been removed. This filling is accomplished with a dragline or similar equipment. In a still yet further form of the process, the trench is a longitudinally-extending series of trenches into which, one-by-one, sump liquid is pumped and dirt previously excavated therefrom is pushed or otherwise directed. In a yet further still form of the process, approx-imately 2/3 of the trench is filled by the resultant mixture.
All forms of the process may also have the spreading of top soil around the well site as a concluding step.
The well site sump liquid disposal process of the subject invention is a simpler process than that of the Schleede patent, requiring only a backhoe instead of special continuous excavation equipment. Other benefits of the well site sump liquid disposal process of the subject invention over the Schleede process are the more even saturation of the soil by the sump liquid and the better opportunity for evaporation with resulting faster completion.
The accompanying drawings illustrate a specific embodiment of the subject invention.
Figure 1 is a top view of a well site during drilling of the well.
Figure 2 is a top view of the same well site after drilling has been completed and soil windrows have been formed at the site.
Figure 3 is a top view of the same well site after completion of a trench adjacent to the soil windrows.
Figure 4 is a top view of the same well site after transfer of the sump liquid and after back filling of the sump pit and trench.
Referring now to the specific embodiment of this ~.

invention, as illustrated in the drawings, a top soil dike lO surrounds a centred well hole 11 at a wellsite 12. Presence of the dike 10 is not necessary for the proper operation of - this invention; however, it is included for completeness since many well sites have such dikes on their periphery.
A sump pit 13 is adjacent to well hole ll and contains a slurry that is cycled through the drilling equipment for lubrication and cutting purposes. The slurry is composed of water, clay additives, and accumulated contaminants.
Soil excavated during the formation of sump pit 13 is piled in a mound 14, located adjacent to the pit. A road 15 allows entry to the well site.
After completion of drilling of the well hole, sump pit 13 is no longer required. Windrows 16 are created at the well site by scraping soil from the surface of the well site. The windrows are located between the sump pit 13 and dike 10 (outlying windrows), and also can be located adjacent to the sides of sump pit 13 (pit windrows).
A grader could create such windrows quickly and efficiently.
2Q Each of the windrows of loose soil, as better illustrated in Figure 2, is 2 to 2 1/2 feet high, 15 to 20 feet wide, with the outlying windrows having a length comparable to that of the well site.
Next, a trench 17 is dug on the well site, adjacent to the outlying windrows, as better illustrated in Figure 3.
In the specific embodiment illustrated in Figure 3, the outlying windrows and the trench 17 adjacent thereto extend around two sides of the well site. However, they could extend around more or fewer of the sides. The trench 17 is sectioned longitudinally into segments 18 by partitions 19, which have an approximate separation of 10 feet. Parti-tions ~z~o~

19 are formed either by replacing part of excavated trench material 20 after completion of a continuous trench or by excavation of a longitudinal series of trench segments.
Trench 17 should not extend through material more porous than that excavated to form sumppit 13. For instance, it should not extend into a gravel seam. Preferably, the trench 17 will extend only into soil or clay. A pump 21 has an inlet pipe 22 extending into the slurry in the sump pit and an outlet pipe 23 extending into one of the sectioned segments 18 of trench 17.
The sump pit slurry is pumped into one of the trench segments 18 and, simultaneously, adjacent excavated trench material is pushed or otherwise directed thereinto.
After that trench segment is approximately 2/3 full of the resulting mixture, outlet pipe 23 is moved to an adjacent trench segment and the process repeated. To save time, filling of trench segments would occur simultaneously with excavation of other parts of the trench.
While sump pit slurry is being pumped into the trench, a sprayer(s) 24 can be fed sump pit slurry through an inlet pipe connected to sump pit 13 and can be utilized to spray the slurry over the windrows 16. Part o the sump pit slurry is also sprayed onto excavated pit material 14. Spraying the slurry over the large surface area of the windrows 16 and excavated pit material 14 allows for rapid evaporation of the water from the slurry. After the windrows have been maintained in a saturated condition- by a continual spray of sump pit slurry and continual evaporation of the water therefrom, the contaminated outlying windrows 16 are pushed into the adjacent trench segments, which have ~3.;~

already been partially filled with the mixture of sump pit slurry and excavated trench material.
In the foregoing manner, all of the slurry is removed from the sump pit 13. After the slurry has been removed from the pit, excavated pit material 14 is pushed or otherwise directed back into sump pit 13 along with any pit windrows 16 that may have been utilized. A dragline could be used for this operation. Any excavated trench material not already utilized with the sump pit slurry to form the mixture in the trench is pushed or otherwise directed into trench 17 and sump pit 13, or is spread across the top of the well site to replace the surface soil collected for windrows. Finally, the top soil forming the dike 10 around the well site is spread over the well site. After completion of the foregoing steps, the only remaining distinguishing features of the well site are the well hole 11 and the road 15 leading thereto, as hetter illustrated in Figure 4.
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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for disposing of well site sump liquid from a sump liquid pit after completion of a drill hole, comprising the steps of:
loosening surface soil at the well site and piling the loosened soil into windrows, excavating a trench adjacent to the windrows, spraying the windrows periodically with part of the sump liquid so as to maintain at least partial saturation thereof while allowing evaporation therefrom, pumping a further portion of the sump liquid into the trench, and pushing or otherwise directing into the trench both the dirt previously excavated from the trench and the windrows.

2. A process for disposing of well site sump liquid from a sump liquid pit after completion of a drill hole, comprising the steps of:
loosening surface soil at the well site and piling the loosened soil into windrows, excavating a trench adjacent to the windrows, spraying the windrows periodically with part of the sump liquid so as to maintain at least partial saturation thereof while allowing evaporation therefrom, pumping a further portion of the sump liquid into the trench and pushing or otherwise directing thereinto the dirt previously excavated therefrom, until the resultant mud mixture fills a substantial part of the trench, and pushing or otherwise directing the windrows into the trench.

3. A process as in claim 1, and additionally comprising the steps of:
piling some of the loosened dirt into additional windrows adjacent to the sump liquid pit, spraying the additional windrows periodically with part of the sump liquid, and pushing or otherwise directing the additional windrows into the sump liquid pit after the remainder of the sump liquid has been pumped from that pit.

4. A process as in claim 2, and additionally comprising the steps of:
piling some of the loosened dirt into additional windrows adjacent to the sump liquid pit, spraying the additional windrows periodically with part of the sump liquid, and pushing or otherwise directing the additional windrows into the sump liquid pit after the remainder of the sump liquid has been pumped from that pit.

5. The process of claim 1, wherein the further portion of the sump liquid is pumped into the trench simultaneously with the pushing or otherwise directing thereinto of dirt previously excavated therefrom.

6. The process of claim 2, wherein the remainder of the sump liquid is pumped into the trench simultaneously with the pushing or otherwise directing thereinto of dirt previously excavated therefrom.

7. The process of claim 1, and also comprising the step of pushing or otherwise directing part of the dirt excavated from the trench into the sump liquid pit after the sump liquid has been removed from that pit.

8. The process of claim 2, and also comprising the step of pushing or otherwise directing part of the dirt excavated from the trench into the sump liquid pit after the sump liquid has been removed from that pit.

9. The process of claim 1, wherein the trench is a longitudinally-extending series of trench segments, into which one-by-one, sump liquid is pumped and dirt previously excavated therefrom is pushed or otherwise directed.

10. The process of claim 2, wherein the trench is a longitudinally-extending series of trench segments, into which one-by-one, sump liquid is pumped and dirt previously excavated therefrom is pushed or otherwise directed.

11. The process of claim 2, 4 or 6, wherein approximately 2/3 of the trench is filled by the resultant mud mixture prior to pushing or otherwise directing the windrows thereinto.

12. The process of claim 8 or 10, wherein approximately 2/3 of the trench is filled by the resultant mud mixture prior to pushing or otherwise directing the windrows thereinto.

13. The process of disposing of well site sump liquid from a sump liquid pit after completion of a drill hole as in claim 1, 2 or 3, and further comprising the step of spreading top soil around the well site.

14. The process of disposing of well site sump liquid from a sump liquid pit after completion of a drill hole as in claim 4, 5 or 6, and further comprising the step of spreading top soil around the well site.

15. The process of disposing of well site sump liquid from a sump liquid pit after completion of a drill hole as in claim 7, 8 or 9, and further comprising the step of spreading top soil around the well site.

16. The process of disposing of well site sump liquid from a sump liquid pit after completion of a drill hole as in claim 10, 11 or 12, and further comprising the step of spreading top soil around the well site.