Abstract In the wire line instruments used for measuring bottom hole pressure and temperature in deep bore holes in the earth, particularly wells used for the production of petroleum liquids and gases, a Bourdon tube is used as the pressure sensing element. This invention relates to an improved method of isolating the liquid inside of the Bourdon tube from the contamination of the well fluids, while still maintaining an accurate transmission of well fluid pressure to the Bourdon tube. In place of the conventional bellows which has been used to isolate the Bourdon tube from the well fluids, this invention involves a long slender helical tubing which is connected to the Bourdon tube at its upper end and to the well fluids at its lower end. The volume of liquid inside the helical tube is several times the volumetric liquid flow of well fluids into the tubing so that contamination which may enter the bottom of the tubing never reaches the top. Means are provided for flushing out, from the top, the liquid in the helical tubing and for cleaning out from the bottom end, the contaminated well fluids which have been forced into the bottom of the tubing under the bottom hole pressure in the well.
In an instrument for use in deep bore holes for measuring the pressure in the well fluids, said instrument having a pressure sensing element filled with clean hydraulic liquid; the improvement comprising means to transmit to said sensing element the pressure of said well fluids while isolating said sensing element from contamination by said well fluids, comprising: a. a long, small-bore tubing filled with clean hydraulic liquid, a first end of said tubing connected to said sensing element, the second end of said tubing open to said well fluids, the internal volume of said tubing greater than the volume of fluid that will flow into said sensing element under the highest pressure to which it will be subjected; and b. means at said first end of said tubing for connection to a pressurized source of hydraulic liquid; whereby said pressurized hydraulic liquid can be used to backflush the hydraulic liquid out of said second end of said tubing, and with it any contamination that may have been left inside said tubing due to the influx of said well fluids into said second end.
Claim 2
Dependent Claim
183 words
In an instrument for use in deep bore holes for measuring the pressure in the well fluids, said instrument having a pressure sensing element filled with clean hydraulic liquid; the improvement comprising means to transmit to said sensing element the pressure of said well fluids while isolating said sensing element from contamination by said well fluids, comprising: a. a long, small-bore tubing filled with clean hydraulic liquid, a first end of said tubing connected to said sensing element, the second end of said tubing open to said well fluids, the internal volume of said tubing greater than the volume of fluid that will flow into said sensing element under the highest pressure to which it will be subjected; and b. means at said first end of said tubing for connection to a pressurized source of hydraulic liquid; whereby said pressurized hydraulic liquid can be used to backflush the hydraulic liquid out of said second end of said tubing, and with it any contamination that may have been left inside said tubing due to the influx of said well fluids into said second end.
Claim 3
Dependent Claim
37 words
The improvement as in claim 1 in which the internal volume of said tubing is at least three times the volume of liquid which will flow into said sensing element under the highest pressure to be measured.
Claim 4
Dependent Claim
24 words
The improvement as in claim 1 including means to close off said second end of said tubing except when said instrument is in use.
Claim 5
Dependent Claim
19 words
The improvement as in claim 1 in which said tubing is in the form of a small diameter helix.