Method and apparatus for controlling a pump upstream of a centrifuge

#This invention relates generally to a method and apparatus for removing solids entrained in a liquid, and particularly to a method and apparatus for removing sand, silt, and clay-sized particles entrained in a drilling fluid.

#In surface drilling, a drill bit at one end of a drill rod is suspended from a traveling block in a drilling derrick and used to crush and cut a bore hole in the earth. The drilling derrick may be as much as 150 feet high and designed for loads of up to 600 tons. If a drilling operation is on a more limited scale, a collapsible mast on a mobile chassis may be used to suspend the drill string.

#A square rod or kelly, suspended from the kelly bushing, engages a socket in a power-driven turntable which transmits rotary motion to the drill string and thus to the drill bit attached to the end of the string. The drill rod and extensions are typically hollow. During drilling, a fluid is pumped down through the rod which rises to the surface through the annular space between the rod and the wall of the bore hole. The liquid, which in most instances consists of water to which certain substances are added to increase its specific gravity, is referred to as "drilling mud" and is kept in circulation in the bore hole by a pump. The drilling mud cools the drill bit and removes cuttings from the bottom of the drill hole by carrying them to the surface in the annular space between the drill string and the bore hole wall.

#A better understanding of the benefits and advantages provided by my invention may be obtained from the appended detailed description and drawings, wherein:

#FIG. 1 is a generalized plan view of a drilling mud circulation system broadly encompassing the instant invention;

#FIG. 2 is a schematic diagram of the primary components comprising the invention;

#For purposes of the following description, the terms "upper," "lower, " "right, " "left, " "rear," "front," "vertical," "horizontal" and derivatives thereof shall relate to the invention as oriented in each figure. However, it is to be understood that the invention may assume various alternative configurations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not be considered as limiting, unless the claims expressly state otherwise.

#Referring to the drawing figures, like reference numerals will be used to indicate the same or like components, wherein FIG. 1 is a generalized plan view of a fluid circulating and solids control system 10 as preferably used in rotary drilling in the earth. A drilling tower or derrick 12 is used to suspend a drilling rod or string 14 from a traveling block and swivel 16. Drilling rod 14 concentrically passes through a larger diameter pipe or casing 15, and often a blowout preventer 18, used to prevent collapse of the bore hole wall and explosive eruption of the well caused by pressurized gas trapped in the subsurface. Drilling mud is pumped down the center of drill string 14 to cool and lubricate the drill bit, control bore hole pressure, and clean cuttings from the bottom of the bore hole during the drilling process. The returning drilling fluid passes up the bore hole in the annular space between drill string 14 and the bore hole wall or casing 15. Upon reaching the top of casing 15, the drilling fluid flows through pipe 20 to a conventionally known shale shaker 22 mounted above shaker pit 24. Frequently, conventionally known cyclonic desanders 26 and desilters 28 are also provided. Together, shale shaker 22, desanders 26, and desilters 28 provide the first phase of solid removal from the drilling fluid, depositing Solid particles larger than clay in container 30.

#Coupled in series fluid communication with shaker pit 24 through valved pipe 32 is a suction tank or pit 34. Suction pit 34 contains a plurality of compartments 36 placed in series fluid communication through weir gates or passages 38. The last compartment 36a of suction tank 34 is in fluid communication through pipe 40 with a mud mixing unit 42 where additives are introduced to the drilling fluid to increase the specific gravity, and decrease fluid loss into the walls of the bore hole. From mud mixing unit 42, the drilling fluid is forced by pump 44 through pipe 46, stand pipe 48, and kelly hose 49 back down drill string 14.