# The method of temperature correction unit accelerometers in the drilling process

The invention relates to the drilling of the measuring technique, in particular to the means of control of downhole parameters during drilling and geophysical exploration wells. The technical result of the invention is to improve the accuracy of the temperature correction (TC) of the output signals of the accelerometers in the process of drilling through constant monitoring of the temperature together with the constant monitoring module of the acceleration vector (MVD) gravity while reducing time-temperature testing in the heat chambers. To do this, in laboratory conditions in a heat chamber measured output signals of the accelerometers to determine the coefficients of their TC. Then in the process of drilling or exploration wells measured output signals of the accelerometers, and temperature sensors and determine the adjusted output signals of the accelerometers G_{xt}, G_{yt}and G_{zt}. These values calculate MVD gravitycompare it with the value LOF |G, determined in normal conditions without correction. If the difference of these values is less than the specified, then the adjusted signals are true. If not, then sequentially change the ratios of TC for all three auctionee signals will be considered true. 1 Il.

The invention relates to the drilling of the measuring technique, in particular to the means of control of downhole parameters during drilling and geophysical studies of the well.

There is a method of determining change settings compensating accelerometer that includes a test of the accelerometer in a heat chamber at two positions: the initial and rotated 180° from the initial position. At each position to conduct two cycles of measurements, one at the temperature t_{1}°_{}C, the other at the temperature t_{2}°_{}C. In each cycle measured output signal of the accelerometer in its original position, turn the accelerometer on some angle, measure the output signal, then turn the accelerometer on some angle in the other direction, again measured output signal, turn the accelerometer relative to the axis of suspension, after which the measurement cycle is repeated. From the ratios measured in each cycle values for the calculated dependences determine the parameters of the accelerometer on all four cycles of testing (see and.with. The USSR №1755205 class. G 01 P 21/00 publ. 1992).

The disadvantage of this method is that for nematodewuchereria temperature influences essentially nonlinear character, as well as a significant zero offset required a large amount of laboratory testing of accelerometers in heat chambers to account for the error of the output voltage of the accelerometer.

In addition, there is no total control over temperature error block, consisting of three orthogonal accelerometers after temperature correction of each accelerometer, and technology for reducing this error in the operation of block accelerometers.

The closest way temperature correction to the claimed method is temperature correction inclinometer angles, designed to control the trajectory of the wellbore or the position of the drilling tool during the drilling of wells, based on the measurement of accelerations and projections of the angular velocity along three mutually perpendicular axes by means of three uniaxial accelerometers and two threefold gyroscopes, the amplification of the output signals of the gyroscopes, converting them into code, correction of these signals depending on the temperature inside the inclinometer measurement survey corners with the help of a computer placed in the body of the inclinometer, and transfer to the surface of the Earth Kahn is the lack of control over temperature error correction, arising in the measurement while drilling or well surveys, when the temperature in the well may vary to some extent from point to point in time or over time, and in the absence of technologies for reducing this error if necessary.

The aim of the invention is to improve the accuracy of the temperature correction of the output signals of the accelerometers in the process of drilling through constant monitoring of the temperature together with the constant monitoring module of the vector acceleration of gravity while reducing time-temperature testing in the heat chambers.

This objective is achieved in that in the method of temperature correction unit accelerometers in the drilling process, based on the measurement at given points in the borehole trajectory of the projection of the gravitational acceleration in three mutually perpendicular axis, the temperature measurement unit accelerometer and correction of the output signals of the accelerometers with temperature coefficients obtained experimentally for a range of temperature values from the temperature range of operation of the accelerometers to determine in normal circumstances the module of the vector acceleration specify the tolerance error, the appropriate technoliteracy coefficients output signals of the accelerometers, compare the last module of the acceleration vector obtained in normal conditions and in case of inequality of the compared values takes place simultaneously for all accelerometers search of the temperature coefficients of a range of values of the temperature coefficients obtained experimentally, to equality of the compared values with an accuracy defined by the given tolerance error. The drawing shows a block diagram of a device implementing this method.

The block diagram includes: unit 1 accelerometers that hosts themselves accelerometers 2, 3, 4 and sensor 5 temperature, unit 6, temperature correction of the output signals of the accelerometers, unit 7 forming module of the acceleration vector |G_{t}|, block 8 comparison module of the acceleration vector |G_{t}| this module of the vector obtained in normal conditions, |G|, unit 9 controls the cycle of the formation of the correction of the temperature error.

To implement this method in laboratory conditions in a heat chamber measured output signals of the acceleration sensors 2, 3 and 4 by changing from a small step temperature throughout a given range, locking sensor 5 temperature in the block accelerometers 1. With minimal exposure unit accelerometers 1 at this ti research well measured output signals of the accelerometers 2, 3, 4 sensor 5 temperature and the measured temperature of the block 1 of the accelerometers to determine in block 6 temperature correction using pre-defined temperature coefficients adjusted output signals of the accelerometers G_{xt}, G_{yt}, G_{zt}. These values in the block 7 calculate the module of the vector acceleration of gravity |G_{t}|

Unit 8 compares the magnitude of the module adjusted the acceleration vector |G_{t}| with the value of the module of the acceleration vector |G, determined in normal conditions without correction. If the difference of these values is less than the specified, then the adjusted signals are true, if not, then the control unit 9 gives the command in block 6 temperature correction for the change of the temperature correction coefficients for all three accelerometers 2, 3 and 4, respectively, and the choice of their values sequentially cycle of a range of values for temperature and temperature coefficients, respectively, determined in laboratory conditions, until becomes |G_{t}||G|, then the adjusted signals will be considered true.

Thus, usage is adequate to reduce the time and cost-temperature testing to improve the accuracy of measuring the output signals of the accelerometers during the drilling and testing wells, especially in conditions of instability of the ambient temperature.

Claims

The method of temperature correction unit accelerometers in the drilling process, based on the measurement at given points in the borehole trajectory of the projection of the gravitational acceleration in three mutually perpendicular axis, the temperature measurement unit accelerometer and correction of the output signals of the accelerometers with temperature coefficients obtained experimentally for a range of temperature values from the temperature range of operation of accelerometers, wherein the determine in normal circumstances the module of the vector acceleration specify the tolerance error corresponding to the required accuracy of the module definition of the acceleration vector, calculate the module of the acceleration vector on the adjusted temperature coefficient output signals of the accelerometers, compared with the last module of the acceleration vector obtained in normal conditions and in case of inequality of the compared values takes place simultaneously for all accelerometers search of the temperature coefficient is the number of variables with precision, given a tolerance of error.

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