Method and apparatus for treating natural gas and oil well drilling waste water

Abstract

A method of treating contaminated water effluent from a well drilling operation. The method comprises decomposing organic contaminants in the effluent by bubbling a gas containing ozone through the effluent; adding a coagulant to increase the particle size of solid particles contained in the effluent; adding a flocculant to increase the particle size of solid particles contained in the effluent, thereby forming flocs suspended in the effluent; and filtering the flocs from the effluent to produce a filtrate and flocculated solids. The method may further comprise adding the coagulant into a stream of effluent flowing within a first conduit under controlled shear conditions, and adding the flocculant into a stream of effluent containing pin flocs flowing within a second conduit under controlled shear conditions. The method may further comprise delivering the effluent containing the suspended flocs into a filter through a conduit floating in the effluent contained in the filter.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS[0001]This application claims priority from U.S. Provisional Patent Application No. 61 / 481,370 filed May 2, 2011, the disclosure of which is incorporated herein by reference. This invention is also related to the inventions disclosed in U.S. patent application Ser. No. 12 / 914,072 filed Oct. 28, 2010, and U.S. Provisional Application for Patent No. 60 / 255,504, filed Oct. 28, 2009, the disclosures of which are incorporated herein by reference.BACKGROUND[0002]1. Technical Field[0003]This invention relates to the removal of contaminants from waste water discharged at a gas wellhead, and more particularly to the removal of contaminants from drilling water that is used during the process of drilling a well bore, and that is subsequently discharged from the wellhead. The waste water may contain petroleum-based drilling muds. The waste water may be treated as it is discharged from a well bore, or after it is temporarily stored in a nearby lagoon...

AI Technical Summary

Benefits of technology

[0024]The product water from the instant process is a sodium chloride (brine) solution, which is suitable for reuse as a portion of the makeup water in drilling operations or hydrofracturing operations. The instant process may include an ozone treatment process for removal of organic contamination prior to treatment to improve chemical efficiency and performance. In addition, ozone treatment, or alternately carbon absorptions, may be utilized following filtration to remove any residual organic materials.

Problems solved by technology

The contaminants in this water render it unsuitable for reuse except in small proportions.

Disposal of the water and the organically contaminated solids contained therein has become an expensive proposition for the well developers and also a difficult environmental problem.

New environmental regulations, as well those proposed and likely to be implemented, may severely limit the ability to dispose of or treat this water by conventional means within the states of Pennsylvania and New York as well as Texas, and Idaho among others, and some foreign countries.

Alternatively, previous disposal of the pit water has been accomplished by transport to and subsequent treatment at conventional municipal waste water treatment facilities and specialized industrial treatment facilities, provided that the drilling muds utilized are “water based.” New and pending regulations may severely limit this option.

“Oil based” drilling mud may not be treated in significant quantities in conventional municipal waste water treatment facilities.

In fact, there are considerable limitations to the disposal of “oil based” pit waters altogether.

Elevated levels of these salts limit options for disposal as well.

Both of these conditions may result in the obstruction of portions of the fissures within the shale strata created by the fracking process when the water is reused, if the concentrations of these salts contained in it are excessive.

The presence of the residual or incipient volatile organic chemicals in the return water results in further difficulties in proper reformulation of it as fracking water for reuse.

The pulverized rock cuttings and residual mud present in this pit water represent suspended solids which are unacceptable in hydrofracking or drilling fluids.

This is expensive, and additionally, it may soon be prohibited in many jurisdictions (particularly New York, Pennsylvania and Texas) by new environmental regulations.

Images