Apparatus and method for minimizing solids deposited in a reserve pit

Abstract

A method of minimizing the quantity of solids deposited in a reserve pit of the type used in drilling oil and gas wells. The method is applicable to well sites where drilling is facilitated by the use of drilling fluid and cuttings are generated by a drill bit, lifted to the surface and deposited at a well bore. The method consists of separating cuttings from associated drilling fluid and conveying larger cuttings to a solids storage location, thus bypassing the reserve pit for a good deal of the solid waste generated at a drilling site. Residual drilling fluid is directed to a reservoir such as a suction tank where it can be reused in further drilling operations. Over time the residual drilling fluid in the suction tank will increase in viscosity to the point where the residue is no longer suitable as drilling fluid. Thereupon, a portion of the residue may be discarded from the suction tank to the reserve pit and water or drilling chemicals added to the suction tank to revitalize the drilling fluid.

What is claimed is:  
     
         1 . A method of minimizing the quantity of solids deposited in a reserve pit of the type used in drilling oil or gas wells where drilling is facilitated by the use of drilling fluid and cuttings are generated by a drill bit, lifted to the surface and deposited at a well bore, the method comprising the steps of: 
 a. directing the cuttings and associated drilling fluid from the well bore to a coarse separating means;    b. separating larger cuttings from a residue comprising drilling fluid and associated smaller cuttings by action of the coarse separating means;    c. conveying the larger cuttings from the coarse separating means to a solids storage location;    d. directing the residue from the coarse separating means to a reservoir;    e. returning the residue from the reservoir to the well for use as drilling fluid in further drilling operations; and    f. discarding a portion of the residue from the reservoir to the reserve pit when the viscosity of the discarded portion renders it no longer suitable as drilling fluid.    
     
     
         2 . The method of  claim 1  wherein the coarse separating means is a rig shaker.  
     
     
         3 . The method of  claim 1  wherein the larger cuttings are conveyed from the coarse separating means an auger.  
     
     
         4 . The method of  claim 1  wherein the coarse separating means separates cuttings too large to fit through a 100 micron screen from the residue.  
     
     
         5 . The method of  claim 1  wherein step c. comprises: 
 conveying the larger cuttings from the coarse separating means to a means for drying solids;  
 drying the larger cuttings in the means for drying solids creating dried solids; and  
 conveying the dried solids to the solids storage location.  
 
     
     
         6 . The method of  claim 7  wherein the means for drying solids is a High-G dryer.  
     
     
         7 . The method of  claim 1  wherein step d. comprises: 
 directing the residue from the coarse separating means to a medium separating means;  
 separating smaller cuttings from the residue by action of the medium separating means;  
 directing the residue from the medium separating means to the reservoir; and  
 conveying the smaller cuttings from the medium separating means to the solids storage location.  
 
     
     
         8 . The method of  claim 7  wherein the medium separating means is a hydrocyclone.  
     
     
         9 . The method of  claim 7  wherein the medium separating means separates cuttings too large to fit through a 50 micron screen from the residue.  
     
     
         10 . The method of  claim 7  wherein the residue is further conveyed to a fine separating means prior to the reservoir, the method further comprising: 
 separating fine cuttings from the residue by action of the fine separating means;  
 directing the residue from the fine separating means to the reservoir; and  
 conveying the fine cuttings from the fine separating means to the solids storage location.  
 
     
     
         11 . The method of  claim 10  wherein the fine separating means is a centrifuge.  
     
     
         12 . An apparatus for handling the cuttings associated with the drilling of an oil or gas well where drilling is facilitated by the use of drilling fluid and cuttings are generated by a drill bit, lifted to the surface and deposited at a well bore, the apparatus comprising: 
 coarse separating means receiving the cuttings and associated drilling fluid from the well bore and separating the larger cuttings from a residue comprising smaller cuttings and drilling fluid;    a solids storage location receiving the larger cuttings from the coarse separating means;    a reservoir receiving the residue from the coarse separating means;    means for returning the residue from the reservoir to the well for use as drilling fluid in further drilling operations; and    a reserve pit receiving a discarded portion of the residue from the reservoir when the viscosity of the discarded portion renders it no longer suitable as drilling fluid.    
     
     
         13 . The apparatus of  claim 12  wherein the coarse separating means is a rig shaker.  
     
     
         14 . The apparatus of  claim 12  wherein the means for conveying the larger cuttings from the coarse separating means is an auger.  
     
     
         15 . The apparatus of  claim 12  further comprising a solids dryer receiving the larger cuttings from the separating means.  
     
     
         16 . The apparatus of  claim 12  further comprising a medium separating means receiving the residue from the coarse separating means.  
     
     
         17 . The apparatus of  claim 16  wherein the medium separating means is a hydrocyclone.  
     
     
         18 . The apparatus of  claim 16  further comprising a fine separating means receiving the residue from the medium separating means.  
     
     
         19 . The apparatus of  claim 18  wherein the fine separating means is a centrifuge.  
     
     
         20 . An apparatus for handling the cuttings associated with the drilling of an oil or gas well where drilling is facilitated by the use of drilling fluid and cuttings are generated by a drill bit, lifted to the surface and deposited at a well bore, the apparatus comprising: 
 a rig shaker receiving the cuttings and associated drilling fluid from the well bore and separating the larger cuttings from a residue comprising smaller cuttings and drilling fluid;    an auger conveying the larger cuttings from the rig shaker to one of a solids dryer and a three sided tank;    a reservoir receiving the residue from the rig shaker;    a return loop in fluid communication with the reservoir and the well bore for returning the residue in the reservoir to the well for further drilling operations; and    a reserve pit receiving a discarded portion of the residue from the reservoir when the viscosity of the discarded portion renders it no longer suitable as drilling fluid.