GB2110374A - Device for measuring inclination electrically - Google Patents

Abstract

A device for measuring inclination comprises a vessel partly filled with mercury or some other flowable conductive liquid or fluent powder, the wall 1 or 2, of the vessel being provided with a series of parallel resistance strips which in the horizontal position of the vessel are equally immersed in the mercury (3). When the device is tilted, the resistances of the unimmersed parts of the strips vary and the difference between the maximum and minimum resistance is a measure of the inclination and the position of the maximum and minimum resistance is a measure of the direction of the inclination. The measurements of resistance may be fed to a micro- processor which can then extrapolate them into a sinusoidal form to give exact measurements of both the angle and direction of inclination. <IMAGE>

Description

SPECIFICATION Device for measuring inclination This invention relates to devices for measuring inclination or drift.

While the device in accordance with the present invention is initially designed for mounting in a drill stack to measure its inclination from the vertical, and particularly in connection with the drilling apparatus described and claimed in my copending application No. 8134337 filed simultaneously herewith and entitled "Drilling Apparatus and Method", it will be understood that it has wider applications. For instance it may be usable as an instrument to be incorporated with existing or future methods employed in the drilling industry. Also, it may find wider application outside the drilling industry.

In accordance with the present invention there is provided a device for measuring inclination comprising a vessel having a wall carrying a plurality of electrical resistance strips, a body of conductive liquid or liquid-like material in the vessel immersing and in electrical contact with a lower part of each strip and having a free surface selecting a horizontal position to leave a part of each strip uncovered, and means for measuring the effective resistance of the uncovered length of each strip.

It is preferred that the said vessel wall should be cylindrical and that the resistance strips shall be parallel with the axis of the cylinder.

The conductive liquid is preferably mercury and to reduce the amount of this heavy and expensive material required, the vessel may be of annular cross section. Other liquids may be used or alternatively a flowable powder could act as a liquid-like material. A suitable inert gas may be used above the liquid.

The device is preferably associated with a microprocessor which is programmed to derive the angle of deviation of the wall from the vertical and the direction of the deviation from the resistance measurements made.

The invention will be further described with reference to the accompanying drawings, in which: Figure 1 is a vertical sectional view through a device in accordance with a preferred form of the invention; Figure 2 is a plan view of the device of Figure 1; Figure 3 illustrates the device in a tilted position; and Figure 4 is a histogram of the resistances measured.

The vessel consists of a double walled cylinder with an inner wall 1 and an outer wall 2 between which is enclosed a body 3 of mercury which in the horizontal position shown in Figure 1 assumes a horizontal surface indicated at 4. As illustrated in Figure 2, either the wall 1 or the wall 2 is provided with a plurality of closely spaced resistance strips, only a proportion of which are illustrated, and which have been given the references Rio to R5. In the horizontal position illustrated in Figure 1, it will be realized that the resistances of all the resistance strips will be similar, but in the tilted position shown in Figure 3, greater lengths of some resistance strips will be exposed than of others varying between a maximum for the strip RP and a minimum for the diametrically opposed strip which is very largely immersed in the mercury.

By ascertaining the difference between the maximum and minimum resistances, the actual amount of tilting can be calculated very readily and by ascertaining positions of the maximum and minimum resistance strips, the actual correction of inclination can also be ascertained.

In practice, the resistances of the various strips will be measured and the resulting information fed to a microprocessor which will provide the required information. In particular, the microprocessor may also be programmed to extrapolate a smooth sinusoidal curve, indicated at 6 in Figure 4, from the measured resistances and thereby arrive at more accurate measurements of the inclination and its direction, since it will be understood that the maximum and minimum inclination will not normally coincide with any one strip but will normally be found between two. Figure 4 shows the maximum resistance as R M and a minimum as Rm In addition, a microprocessor may also be used to average a varying resistance and arrive at the histogram and curve of Figure 4 even if no steady state can be achieved.

Various modifications may be made within the scope of the invention.

Claims

1. A device for measuring inclination comprising a vessel having a wall carrying a plurality of electrical resistance strips, a body of conductive liquid or liquid like material in the vessel immersing and in electrical contact with a lower part of each strip and having a free surface selecting a horizontal position to leave a part of each strip uncovered, and means for measuring the effective resistance of the uncovered length of each strip.

2. A device as claimed in claim 1, in which the said vessel wall is cylindrical and the strips are parallel with the axis of the cylinder.

3. A device as claimed in claim 2, in which the vessel is of annular cross section.

4. A device as claimed in claim 1, 2 or 3, in which the conductive liquid is mercury.

5. A device as claimed in claim 1, 2, 3 or 4, associated with a microprocessor which is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Device for measuring inclination This invention relates to devices for measuring inclination or drift. While the device in accordance with the present invention is initially designed for mounting in a drill stack to measure its inclination from the vertical, and particularly in connection with the drilling apparatus described and claimed in my copending application No. 8134337 filed simultaneously herewith and entitled "Drilling Apparatus and Method", it will be understood that it has wider applications. For instance it may be usable as an instrument to be incorporated with existing or future methods employed in the drilling industry. Also, it may find wider application outside the drilling industry. In accordance with the present invention there is provided a device for measuring inclination comprising a vessel having a wall carrying a plurality of electrical resistance strips, a body of conductive liquid or liquid-like material in the vessel immersing and in electrical contact with a lower part of each strip and having a free surface selecting a horizontal position to leave a part of each strip uncovered, and means for measuring the effective resistance of the uncovered length of each strip. It is preferred that the said vessel wall should be cylindrical and that the resistance strips shall be parallel with the axis of the cylinder. The conductive liquid is preferably mercury and to reduce the amount of this heavy and expensive material required, the vessel may be of annular cross section. Other liquids may be used or alternatively a flowable powder could act as a liquid-like material. A suitable inert gas may be used above the liquid. The device is preferably associated with a microprocessor which is programmed to derive the angle of deviation of the wall from the vertical and the direction of the deviation from the resistance measurements made. The invention will be further described with reference to the accompanying drawings, in which: Figure 1 is a vertical sectional view through a device in accordance with a preferred form of the invention; Figure 2 is a plan view of the device of Figure 1; Figure 3 illustrates the device in a tilted position; and Figure 4 is a histogram of the resistances measured. The vessel consists of a double walled cylinder with an inner wall 1 and an outer wall 2 between which is enclosed a body 3 of mercury which in the horizontal position shown in Figure 1 assumes a horizontal surface indicated at 4. As illustrated in Figure 2, either the wall 1 or the wall 2 is provided with a plurality of closely spaced resistance strips, only a proportion of which are illustrated, and which have been given the references Rio to R5. In the horizontal position illustrated in Figure 1, it will be realized that the resistances of all the resistance strips will be similar, but in the tilted position shown in Figure 3, greater lengths of some resistance strips will be exposed than of others varying between a maximum for the strip RP and a minimum for the diametrically opposed strip which is very largely immersed in the mercury. By ascertaining the difference between the maximum and minimum resistances, the actual amount of tilting can be calculated very readily and by ascertaining positions of the maximum and minimum resistance strips, the actual correction of inclination can also be ascertained. In practice, the resistances of the various strips will be measured and the resulting information fed to a microprocessor which will provide the required information. In particular, the microprocessor may also be programmed to extrapolate a smooth sinusoidal curve, indicated at 6 in Figure 4, from the measured resistances and thereby arrive at more accurate measurements of the inclination and its direction, since it will be understood that the maximum and minimum inclination will not normally coincide with any one strip but will normally be found between two. Figure 4 shows the maximum resistance as R M and a minimum as Rm In addition, a microprocessor may also be used to average a varying resistance and arrive at the histogram and curve of Figure 4 even if no steady state can be achieved. Various modifications may be made within the scope of the invention. Claims

1. A device for measuring inclination comprising a vessel having a wall carrying a plurality of electrical resistance strips, a body of conductive liquid or liquid like material in the vessel immersing and in electrical contact with a lower part of each strip and having a free surface selecting a horizontal position to leave a part of each strip uncovered, and means for measuring the effective resistance of the uncovered length of each strip.

2. A device as claimed in claim 1, in which the said vessel wall is cylindrical and the strips are parallel with the axis of the cylinder.

3. A device as claimed in claim 2, in which the vessel is of annular cross section.

4. A device as claimed in claim 1, 2 or 3, in which the conductive liquid is mercury.

5. A device as claimed in claim 1, 2, 3 or 4, associated with a microprocessor which is programmed to derive the angle of deviation of the wall from the vertical and the direction of the deviation.

6. A device for measuring inclination substantially as hereinbefore described with reference to the accompanying drawings.