Closed loop drilling fluids circulation and management system

Abstract

A closed loop drilling fluids circulation system includes a first drilling fluid circulation system disposed at a first subterranean drill site. The first drilling fluid circulation system includes a supply tank for holding clean drilling fluid and a solids control device configured to separate solids from used drilling fluid. In addition, the system includes a central processing facility disposed at a location remote from the first drill site and configured to receive used drilling fluid from the solids control device and supply clean drilling fluid to the supply tank.

What is claimed is: 
     
         1 . A closed loop drilling fluids circulation system comprising:
 a first drilling fluid circulation system disposed at a first subterranean drill site, wherein the first drilling fluid circulation system includes a supply tank for holding clean drilling fluid and a solids control device configured to separate solids from used drilling fluid; and   a central processing facility disposed at a location remote from the first drill site and configured to receive used drilling fluid from the solids control device and supply clean drilling fluid to the supply tank.   
     
     
         2 . The system of  claim 1 , wherein the central processing facility comprises a degasser configured to remove gas from the used drilling fluid, solids separation equipment configured to remove solids from the used drilling fluid, and a transfer pump configured to pump clean drilling fluid to the supply tank. 
     
     
         3 . The system of  claim 1 , wherein the first drilling fluid circulation system is a sealed and pressurized system. 
     
     
         4 . The system of  claim 3 , wherein the first drilling fluid circulation system further comprises:
 a return pump configured to pump used drilling fluid from the solids control device to the central processing facility; and   a supply pump configured to pump clean drilling fluid from the supply tank down a drillstring.   
     
     
         5 . The system of  claim 4 , wherein the return pump is configured to pump used drilling fluid from an annulus in a borehole to the solids control device. 
     
     
         6 . The system of  claim 3 , wherein the solids control device comprises:
 a housing having an inner chamber, a first end including an inlet, and a second end including an outlet;   a baffle disposed in the inner chamber, the baffle having an upstream end proximal the inlet, a downstream end proximal the outlet, and an upper surface extending from the upstream end to the downstream end;   wherein the upper surface is positioned vertically above the inlet at the upstream end.   
     
     
         7 . The system of  claim 6 , wherein the baffle divides the inner chamber of the solids control device into an upper portion disposed above the baffle and a lower portion disposed below the baffle;
 wherein the upper portion is configured to allow the flow of used drilling fluid from the inlet to the outlet and the lower portion is configured to collect solids separated from the used drilling fluid.   
     
     
         8 . The system of  claim 7 , wherein the housing includes a solids-cleanout port for removing solids from the lower portion. 
     
     
         9 . The system of  claim 3 , wherein the first drilling fluid circulation system further comprises:
 a surge vessel upstream of the solids control device and configured to agitate the used drilling fluid.   
     
     
         10 . The system of  claim 4 , wherein the central processing facility includes a gas-tight degasser configured to remove gas from the used drilling fluid. 
     
     
         11 . The system of  claim 10 , wherein the degasser has an inlet for receiving used drilling fluid from the return pump, a drilling fluid outlet, and a gas outlet in sealed fluid communication with a gas storage vessel. 
     
     
         12 . The system of  claim 1 , further comprising:
 a second drilling fluid circulation system disposed at a second subterranean drill site, wherein the second drilling fluid circulation system includes a supply tank for holding clean drilling fluid and a solids control device configured to separate solids from used drilling fluid;   wherein the central processing facility is configured to receive used drilling fluid from the solids control device of the second drilling fluid circulation system and supply clean drilling fluid to the storage vessel of the second drilling fluid circulation system.   
     
     
         13 . A drilling fluids circulation system disposed at a drill site, the system comprising:
 a pressurized storage vessel for holding clean drilling fluid at the drill site;   a supply pump configured to pump clean drilling fluid from the pressurized storage vessel down a drill string;   a pressurized surge vessel configured to receive and hold used drilling fluid from an annulus disposed about the drill string;   a sealed and pressurized solids control device configured to receive used drilling fluid from the surge vessel and separate solids from used drilling fluid; and   a return pump configured to pump used drilling fluid from the solids control device.   
     
     
         14 . The system of  claim 13 , wherein the solids control device has an inlet in fluid communication with the surge vessel, an outlet in fluid communication with the return pump, and a solids cleanout port. 
     
     
         15 . The system of  claim 13 , further comprising:
 a central processing facility configured to receive used drilling fluid from the return pump, convert the used drilling fluid into clean drilling fluid, and supply clean drilling fluid to the inlet of the storage vessel.   
     
     
         16 . The system of  claim 13 , wherein the storage vessel has a storage volume equal to or greater than the volume of a borehole disposed about the drill string. 
     
     
         17 . The system of  claim 13 , wherein the drill site is disposed below ground. 
     
     
         18 . The system of  claim 13 , further comprising:
 an instrumentation package for measuring the pressure of the clean drilling fluid pumped down the drill string;   an instrumentation package for measuring the pressure of the used drilling fluid exiting the annulus;   a control module configured to automatically adjust the weight of the clean drilling fluid and the operation of the return and supply pumps based on the measured pressures of the of the clean drilling fluid pumped down the drill string and the pressure of the used drilling fluid exiting the annulus.   
     
     
         19 . A method for circulating and processing drilling fluid, the method comprising:
 (a) receiving used drilling fluid from a borehole at a first subterranean drill site;   (b) preventing the escape of gases from the used drilling fluid at the first subterranean drill site;   (c) pumping the used drilling fluid from the first subterranean drill site to a central processing facility disposed at the surface after (b);   (d) processing the used drilling fluid to form clean drilling fluid at the central processing facility; and   (e) pumping the clean drilling fluid from the central processing facility to the first subterranean drill site after (d).   
     
     
         20 . The method of  claim 19 , further comprising separating at least some solids from the used drilling fluid at the first subterranean drill site. 
     
     
         21 . The method of  claim 19 , further comprising:
 drilling a borehole at the first subterranean drill site with a drillstring;   pumping clean drilling fluid from a pressurized supply tank at the first subterranean drill site down the drill string; and   storing a volume of clean drilling fluid in the supply tank that is equal to or greater than the volume of the borehole.   
     
     
         22 . The method of  claim 21 , further comprising:
 maintaining a pressure of the drilling fluid at a bottom of the borehole substantially equal to a formation pressure.   
     
     
         23 . The method of  claim 22 , further comprising:
 flowing used drilling fluid from an annulus in the borehole;   measuring a pressure of the drilling fluid pumped down the drill string;   measuring a pressure of the drilling fluid flowing from the annulus;   adjusting the pressure of the drilling fluid pumped down the drill string or the pressure of the drilling fluid pumped from the annulus to maintain the pressure of the drilling fluid at a bottom of the borehole substantially equal to the formation pressure.   
     
     
         24 . The method of  claim 19 , wherein (d) comprises:
 (d1) removing gases from the used drilling fluid; and   (d2) preventing the escape of the removed gases into the surrounding environment at the central processing facility.   
     
     
         25 . The method of  claim 19 , further comprising:
 flowing used drilling fluid from the borehole into a pressurized surge tank; and   pumping used drilling fluid from the surge tank to the solids control device.