US 4,303,994 A · System and method for monitoring drill string characteristics during drilling

Abstract

A measurement system detects a downhole drilling variable in relation to the rotational orientation of a drill string during drilling. The system includes a downhole reference signal generator and a downhole variable signal generator. The reference signal generator is coupled downhole to the drill string for generating a downhole reference (DR) signal indicative of the angular relationship between the drill string and a directional reference, such as gravity or the earth's magnetic field. The downhole variable signal generator detects downhole parameters and generates a downhole variable (DV) signal representative of a downhole parameter of interest during drilling. The DV signal and the DR signals are thereupon processed, either downhole or uphole depending in part on the telemetry system employed. The system is especially adapted for indicating the resultant lateral force applied to the drill string at the drill bit during drilling which is useful in projecting the probable drilling direction.

Claims13

Dependent claims

A system operable during the drilling of a borehole for generating a direction signal representative of the direction which the drill bit of a drill string will take during continued drilling, the drill string being of the type which is rotated during drilling of the borehole, comprising:

a. a reference signal generator coupled to the drill string for generating during drilling a reference signal indicative of the rotational orientation of the drill string about its axis with respect to a directional reference;
b. a strain signal generator coupled to said drill string for generating during drilling a strain signal indicative of the lateral forces applied to said drill bit as a function of the rotational orientation of the drill string;
and
c. telemetering and processing circuitry coupled to receive said strain signal and said reference signal for generating said direction signal to represent the phase between said strain and reference signals, thereby to represent the direction of the resultant of said lateral forces as a function of said directional reference.

1 more element

During the drilling of a borehole using a rotating drill string and drill bit, a method for predicting the direction which the borehole will take during continued drilling, comprising the steps of:

a. during rotation of the drill bit, generating downhole a reference signal having values indicative of the rotational orientation of the drill string about its axis with respect to a directional reference;
b. during rotation of the drill bit, generating downhole a strain signal indicative of the lateral forces applied to the drill bit as a function of the rotational orientation of the drill string;
c. in response to said reference signal and to said strain signal, generating a first processed signal representing the phase between said reference signal and said strain signal thereby to represent the lateral forces applied to the drill bit with respect to said directional reference;
d. generating a position signal having a value representative of the positional orientation of the drill bit;
and
e. in response to said first processed signal and to said position signal, generating a direction signal having a value representative of the direction of the resultant of said lateral forces applied to said drill bit as a function of the positional orientation of the drill bit, thereby being indicative of the future direction which the bit will take during continued drilling.

3 more elements

Dependencies are inferred from the claim text.

System and method for monitoring drill string characteristics during drilling

Life of this patent

System and method for monitoring drill string characteristics during drilling

Life of this patent

Abstract

Claims13