RU2298080C2 - Method for bit wear determination during well drilling or secondary hole predrilling - Google Patents

Abstract

FIELD: well drilling, particularly drilling of slightly inclined wells along with current well coordinate measurement.

SUBSTANCE: method involves determining axial load applied to bit, bit rotation speed, drilling mud supply rate and current hole bottom coordinates, namely zenith, apsidal and azimuth angles; measuring natural gamma radiation of rock to be drilled and longitudinal drilling string vibration by means of sensors included in downhole instrument of telemetering system provided with communication channel to communicate hole bottom with day surface; determining lithologically uniform drillable rock bound and longitudinal drilling string vibration corresponding to them; comparing obtained values of actual longitudinal bit vibrations with that obtained from estimated dependence and if above values differ drilling operation is terminated and bit is lifted for inspection thereof.

EFFECT: increased time of bit presence in well bottom.

1 ex, 2 dwg

Description

The invention relates to the field of well drilling, and in particular to methods of sinking and measuring the current coordinates of the bottom hole of inclined horizontal wells during drilling.

A known method for determining the run-in bit by changing (falling) the mechanical speed of penetration more than 2 times. (M.M. Zubkov. Oil and gas field development. Proceedings of the Krasnodar branch of the All-Union Research Institute. 1961, No. 5, p.228-247).

The disadvantage of this method is the low accuracy of determining the drill bit when drilling wells, since this method does not allow to determine and take into account the lithological characteristics of the layers during drilling, so the cause of the decrease in mechanical speed can be not only the run of the bit, but also the transition from less durable rocks to more durable. For example, when drilling in clay deposits, ceteris paribus, the mechanical penetration speed can be 4.2 m / h, and when moving to solid cemented sandstones, its value can decrease to 2 m / h, with a practically unworked bit.

A known method for determining the run-in bit according to the testimony of a rotary momentmeter (for example, IMR-17 or other momentometers). In this method, the bit response is determined by the change in the moment on the rotor, for example, when it (moment) decreases, a conclusion is drawn on the weapon armament of the bit, and when it is increased, it is on the release of the bit supports. (A.I. Bulatov, V.I. Demikhov. Monitoring of oil and gas well drilling processes. Krasnodar, North-Kazakhstan region of the Engineering Academy of Sciences, 1993, 423 pp.).

The disadvantage of this method is the low accuracy of determining the drawdown of the bit when drilling wells, since this method does not allow to determine and take into account the lithological characteristics of the formation rocks during drilling, so the cause of the drop in torque can be not only the drawdown of the bit, but also the transition to the formation rock with other lithological characteristics. The known method does not give an unambiguous answer to the question of whether the bit worked or moved to another breed.

The aim of the present invention is to increase the residence time of the bit at the bottom.

Figure 1 presents a diagram of gamma ray logging.

Figure 2 presents a diagram of the level of longitudinal vibration of the bit.

The method is as follows.

In the process of drilling wells or drilling second shafts, the axial load on the bit, rotational speed of the bit, drilling fluid feed rate, current bottom face coordinates: zenith, obsidial and azimuth angles are determined by the sensors of natural gamma radiation of the drilled rocks and the longitudinal vibration of the drill string installed in the borehole device of the telemetric system with a channel for communicating the bottom face with the day surface, the boundaries of lithologically homogeneous passable rocks and the corresponding longitudinal length are determined The vibration of the bit.

The calculated longitudinal vibration of the bit is determined by the formula:

,

,

where f is the oscillation frequency of the drill string;

where τ _to - the contact time of the tooth of the bit with the rock;

d is the diameter of the cone;

D is the diameter of the bit;

n is the bit rotation frequency;

z is the number of teeth on the peripheral crown of the cone.

The obtained values of the actual longitudinal vibration of the bit are compared with its calculated dependence and, when the values diverge, they stop drilling and raise the bit for inspection.

Example. The telesystem devices developed by us provided telemetric and technological support for drilling an inclined horizontal well (well No. 12 Aleshkinskaya) of OAO Lukoil-Kaliningradneft. During the drilling process, the axial load on the bit, the bit rotation frequency, the drilling fluid feed rate, the current face coordinates: the zenith, obsidial, and azimuth angles were determined by the natural gamma radiation sensors of the rocks passed through and the longitudinal vibration of the drill string installed in downhole instrument of a telemetric system with a channel for communicating the face with the day surface, the boundaries of lithologically homogeneous passable rocks and the corresponding longitudinal vibration of the bit were determined.

The longitudinal vibration of the bit is determined by the formula:

where f is the oscillation frequency of the drill string;

where τ _to - the contact time of the tooth of the bit with the rock;

d is the diameter of the cone (d = 100 mm);

D is the diameter of the bit (D = 215.9 mm);

n is the bit rotation frequency (n = 2 s ^-1 );

z is the number of teeth on the peripheral crown of the cone (z = 12).

According to the readings of the GK sensor, it was clearly noted that the bit entered the productive layer - cambrite, in which the vibration of the bit differed sharply from the vibration in the previous layer. Further on its change, a conclusion was drawn about the chiseling of the bit, which allowed to save 3 bits in relation to the 7 bits set in the project. The proposed method allows to determine in the rocks of which lithology during the drilling of the well the bit works, and then, by changing the level of vibration, judge whether the bit worked or not.

Claims (1)

A method for determining the drill bit during drilling or drilling second shafts, including measuring the axial load on the bit, its rotational speed, drilling fluid feed rate, current face coordinates: anti-aircraft, absolute and azimuth angles and measuring with sensors installed in the borehole telemetry system with the communication channel of the face with the day surface, natural gamma radiation of penetrated rocks and longitudinal vibration of the drill string, determining the lithologically homogeneous Qdim species and corresponding to the longitudinal vibrations of the bit, characterized in that the values obtained for the longitudinal vibrations actual bit compared with the calculated dependence and their divergence stop drilling and lift the drill bit for inspection.

Images