Abstract:
A containment apparatus for collecting liquids including oil and water emitted from a gas buster exhaust stack. The containment includes baffling and a liquid float and discharge line for returning the liquids to a reservoir. Multiple containments may be connected to contain potentially greater discharges.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to gas buster or liquid/gas separation units used in oil and gas well drilling and restoration operations and more particularly to a liquid containment chamber attachable to the exhaust stack of the gas buster units for the prevention of spills and environmental contamination due to liquid laden gas discharge and high pressure gas kicks. 
   GENERAL BACKGROUND 
   A gas buster is a simple separator vessel used to remove free or entrained gas from fluids circulated in the well bore, such as mud used during drilling operations. The gas buster typically comprises a vessel containing a series of baffles with a liquid exit on the bottom and a gas-vent line at the top of the vessel. 
   A buster also separates gas from mud, but it is not a sealed unit and, therefore, does not permit the pressure of the gas to increase sufficiently to enable venting to any appreciable degree. A gas buster generally vents exhaust gas immediately above the well through an eight feet vent pipe. 
   Separators on the other hand are used on less than five percent of all wells and only after the casings have been inserted in a well in anticipation of hitting a large quantity of gas. Gas busters are used more extensively than separators, primarily because busters are less expensive and can be constructed quickly to meet emergency situations. 
   It is now required that a mud-gas separator (gas buster) must be installed and operable for all operations of 10M or greater and for any operation where abnormal pressure is anticipated beginning at a point at least 500 feet above any anticipated hydrocarbon zone of interest. 
   During drilling mud is circulated in the borehole and the entrained gases, which can be flammable, are separated in a liquid/gas separator, also commonly referred to in the industry as a gas buster. The separated gases, also commonly specified in the industry as waste gases, exit the top of the gas buster. In some cases the gases are directed down a long pipe, which is oriented down-wind from the rig floor. This pipe is generally about 100 feet long or more and contains an ignition source at its tip. Any flammable gases, which are released from the gas buster, are burned at the tip of the flare line where the ignition source is mounted. This has been a standard set-up for drilling rigs for many, many years. 
   In work-over operations mud separation coming from the well bore is achieved by mounting the gas buster directly on or adjacent to a mud tank in which case mud is ejected from the bottom of the gas buster into the mud tank for recovery and the waste gas is simply vented to atmosphere rather than ignited and burned. 
   Virtually all live wells produce a slightly oily mist from the gas buster stack. In most cases this light liquid simply dribbles down the stack and evaporates or is collected by the mud tank. However, high winds tend to carry this oily discharge a considerable distance down-wind from the stack thereby contaminating the environment. When such operations are being carried out over water this discharge presents an even greater problem. In most cases personnel fail to report such light contamination therefore it is simply ignored. 
   An isolated pocket of natural gas is known as a kick if it is under control and as a blowout if it is not under control. Such kicks occur frequently thereby forcing slugs of oil out of the well at high pressure and at such a velocity that the gas buster is overwhelmed thus forcing liquids out the stack. When this happens it is considered a major spill and it cannot be ignored. High winds also contribute to the spill by taking the oily discharge great distances from the well site or into water causing extensive environmental contamination that requires expensive clean up. 
   SUMMARY OF THE INVENTION 
   A containment apparatus for collecting liquids including oil and water emitted from a gas buster exhaust stack. The containment includes baffling and a liquid float and discharge line for returning the liquids to a reservoir. Multiple containments may be connected to contain potentially greater discharges. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which, like parts are given like reference numerals, and wherein: 
       FIG. 1  is an isometric view of the liquid containment assembly in combination with a gas buster and its mud tank; 
       FIG. 2  is a partial vertical cross section view of the stack, containment and gas buster assembly; 
       FIG. 3  is a partial vertical section view of a second embodiment utilizing plural containments; 
       FIG. 4  is a top view of the baffle plate seen in cross section in  FIGS. 2 and 3 ; 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   As first seen in  FIG. 1  gas buster assemblies  10  are generally mounted above or adjacent to a mud tank  12 . The gas buster  10  or liquid/gas separator is usually fitted with a length of pipe or stack  14  extending upwardly there from for the purpose of discharging waste gases being conveyed to the surface of a well with the drilling mud. 
   Under normal circumstances, the waste gas vapors contain small amounts of oil residue that are gradually dissipated downwind as they cool. However, on occasion kicks or surges occur as a result of gas pockets being trapped within the mud fluid stream. Such kicks often are at high pressure and thus overwhelm the gas buster  10  and force fluid out the stack  14 . Such discharge causes considerable environmental problems and extensive clean up. Therefore, as a preventative measure a surge suppressor may be used in the form of a liquid containment assembly  16  connected to the top of the gas buster outlet before connecting the exhaust stack  14 . 
   The containment assembly  16  as shown in  FIG. 2  is composed of an elongated cylindrical hollow housing  18 . The housing  18  is fitted with an exhaust port at one end threadably adapted for connection to an exhaust stack member  14  by a hammerlock, union coupling member  20  or other suitable means. The opposite end of the housing  18  has an inlet opening  19  for receiving a portion of a tubular member  22 . The housing  18  further includes an internal, baffle plate  26  having a plurality of holes  28  therein defining an outlet exhaust chamber  30 , and a liquid chamber  31 . The liquid chamber  31  includes a cylindrical baffle  32  attached perpendicularly to the baffle plate  26 . 
   The tubular member  22 , including a series of holes  24  located circumferentially around one end with a threaded portion for coupling at the opposite end, is inserted within the housing  18 . The tubular member  22  is centrally located relative to the cylindrical baffle  32  and is secured in a liquid tight manner peripherally around the opening  19  in the manner seen in  FIG. 2  so that the threaded portion extends beyond the housing  18  thus forming the inlet port. 
   A ball float valve assembly  36  penetrates the lower end of the housing  18  adjacent the tubular member  22 . A drain tube  38  is attached to the said float valve  36 . 
   As shown in  FIG. 3  multiple liquid containment assemblies  16  may be stacked one above the other by providing an intermediate or adapter stack  42  composed of a length of tubing threaded at each end for connection by hammerlock, union couplings  20 . 
   In operation, exhaust gas entering the gas buster assembly  10  is entrained within the drilling fluid. When such gas/fluid exceeds the capacity of the gas buster assembly it is expelled upwards into the containment assembly  16  through the tubular member  22  and forced though the holes  24  and allowed to pass below the cylindrical baffle  32  and escape through the holes  28  in the baffle plate  26  and ultimately out the exhaust stack  14 . 
   Fluids  40  are separated from the gas by the baffles and accumulated within the lower chamber  31 . As the fluid level rises the ball valve  36  opens allowing the fluid to return to the mud tank  12  as seen in  FIG. 1 . 
   In some cases the volume of fluids entering the gas buster assembly  10  is simply too great for one containment assembly  16  alone to control the overflow. Therefore, any number of containment assemblies  16  may be added to the exhaust stack as shown in  FIG. 3  thereby allowing the fluids to cool and condense and be returned to the tank  12 . 
   Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in any limiting sense.