3 are designated A, B, and C. An advantageous example of the operation of the apparatus 1 will be described below with reference to FIGS. 2 and 3.
Each apparatus 1 consists of a filter housing 5, a filter 3, a pump 2 with separate ventilation, and monitoring and control 5 equipment. These are operated independently of each other and can be run with different filter inserts depending on the type of screen cloth that is in the corresponding vibrating screen.
During normal operation, the filter housing 5 and the filter 10 3 are in a vertical position in the apparatus 1. Drilling fluid is drawn through inlet pipe 6 (typically about 1" (2.54 cm) in diameter) mounted in the cover 7 over the filter housing 5. The cover 7 surrounds the filter 3 and the filter housing 5 and forms a liquid and gas-proof connection between them. The 15 drilling fluid is drawn into the filter 3 (about 30 to 50 1/min) by the suction pump 2 which is mounted on the outlet side of the filter. When the differential pressure across the filter 3 increases, or other factors dictate that the filter 3 must be checked/replaced, the pump 2 is closed off and the pressure 20 across the filter 3 is balanced by allowing air in.
The filter housing 5 is opened by opening an eccentric lock on the front of the filter housing. This lowers the filter housing 5 so that it is released from the cover 7 (apparatus A). The housing 5 is tilted towards the operator. The cover 7 is opened 25 and the filter 3 is accessible for inspection or replacement. When the filter 3 is to be replaced, it is pulled right out of the filter housing (apparatus B). Excess drilling fluid can then run down into the tray beneath the filter housing 5, thereby avoiding spill on the floor. A new filter insert can be inserted and the 30 unit closed and started in reverse order. During the running of hot drilling fluid, suction across each apparatus 1 will ensure that the operator is not exposed to steam from an open filter housing.
A sampling device 8 is located at the side of the control 35 unit. The sampling device 8 is a ventilated unit having means for taking samples of the cleaned drilling fluid (from any vibrating screen or pit) to carry out necessary tests and analyses. In FIGS. 2 and 3 this is illustrated by direct drawing-off to a funnel viscosimeter. 40
This reduces the exposure time to off-gases from drilling fluid for the drill operators and mud engineers who thus do not need to go into the shaker room to take samples from ducts and pit. (For example, S.G. samples which are taken every fifteen minutes during drilling.) 45
Furthermore, the drawing-off equipment is in the immediate vicinity of the testing apparatuses that are used, thereby avoiding unnecessary spill on gangways.
FIG. 4 shows a flow diagram for apparatuses 1, 1' 1" and sampling device 8. P denotes a pressure gauge, whilst DP 50 denotes a pressure gauge for measuring differential pressure/ pressure difference across the filter 3. M represents a pump motor.
The sampling device 8 is a unit with means for taking samples from the cleaned drilling fluid from any vibrating 55 screen in order to conduct the necessary tests and analyses. T denotes temperature measuring; SG denotes measurement of specific gravity. One possibility in the sampling device may be a Coriolis flowmeter which records amount, specific gravity and temperature. Vise, denotes viscosity measurement. 60
The invention claimed is:
1. An apparatus for checking the condition of a screen for drilling fluid, the apparatus comprising: a screen capable of vibrating;
a bottom tray for receiving fluid from the screen; 65 at least one conduit for conveying a sample of the fluid from the bottom tray;
a filter in fluid communication with the conduit for filtering the fluid sample;
a pump in fluid communication with the conduit and the filter for drawing the fluid sample from the bottom tray and conveying the sample to the filter; and
a pressure measuring system operatively coupled to the conduit and configured to measure a differential pressure across the filter, wherein the differential pressure across the filter indicates the condition of the screen.
2. An apparatus according to claim 1, further comprising a warning device operatively coupled to the pressure measuring system, the warning device configured to provide a warning when the differential pressure exceeds a predetermined limit value.
3. An apparatus according to claim 1, further comprising a sampling device comprising at least one of a pressure measuring system, a temperature meter, a specific gravity meter, a viscosity meter, or a Coriolis flowmeter.
4. An apparatus according to claim 1, wherein the filter comprising a mesh size substantially equal to a mesh size of the screen.
5. An apparatus according to claim 1, wherein the filter comprising a mesh size greater than a mesh size of the screen.
6. An apparatus according to claim 1, further comprising a housing having a first chamber and a second chamber.
7. An apparatus according to claim 6, wherein the filter is disposed between the first chamber and the second chamber.
8. An apparatus according to claim 6, wherein the housing is tiltingly coupled to a rack configured to arrange a plurality of apparatuses.
9. An apparatus according to claim 1, further comprising a plurality of apparatuses arranged in a rack, the apparatuses configured to indicate the condition of a plurality of vibration screens.
10. An apparatus according to claim 9, wherein the plurality of apparatuses operate independently of each other.
11. An apparatus according to claim 9, wherein the filter associated with each apparatus is configured to function with the associated screen of the corresponding vibrating screen.
12. A method for checking the condition of a screen for drilling fluid, comprising:
passing fluid through the screen;
drawing a fluid sample from the screened fluid;
filtering the fluid sample through a filter;
measuring the pressure difference across the filter; and
comparing the pressure difference to at least one predetermined limit value, wherein the pressure difference indicates the condition of the screen.
13. A method according to claim 12, further comprising warning when the pressure difference across the filter exceeds at least one selected predetermined limit value.
14. A method according to claim 12, further comprising drawing a fluid sample into the sampling device for measuring at least one of temperature, pressure, specific gravity, or viscosity of the fluid sample.
15. A method according to claim 12, wherein the filter comprising a mesh size substantially equal to a mesh size of the screen.
16. A method according to claim 12, wherein the filter comprising a mesh size greater than a mesh size of the screen.
17. A method according to claim 12, further comprising collecting in the filter particulates larger than a mesh size of the screen, the collected particulates generating an increased pressure differential across the filter, and indicating a change in the condition of the screen.