Drilling system
AssigneeRocsol Technologies Inc.
InventorGeir Hareland
Life of this patent
Estimating the term…
Abstract
Rock strength is estimated during drilling using a rate of penetration model or a modified mechanical specific energy models. The rock strength estimate can be used in conducting further drilling, for example by a drilling system. Drilling parameters may be altered as a result of determining rock strength, for example to avoid undesirable trending fractures, such as extensive vertical fractures.
Claims21
A method of drilling a well or fracturing a formation drilled by a well, the method comprising the steps of:
- drilling through rock with a drilling system by rotating a drill bit;
- providing a model for calculating the rock mechanical properties and/or specific energy using rate of penetration of the bit through the rock formations being drilled, the model including the strength of the rock and known or estimated parameters, the known or estimated parameters including a measure of bit wear, the model including a proportionality of the rate of penetration of the bit through the rock to a function of the measure of bit wear;
- measuring or estimating a value of the rate of penetration of the bit;
- estimating the strength of the rock according to a value of the strength of the rock required to cause the model to calculate the rate of penetration of the bit to have the measured or estimated value given the known or estimated parameters;
- estimating a rate of change of the measure of bit wear based on the estimated strength of the rock;
- repeating the above steps at at least a subsequent point in time estimating the measure of bit wear at the at least a subsequent point in time using the estimated rate of change of the measure of bit wear;
- and
- setting drilling or fracturing parameters according to the estimated rock strength.
The method of claim in which the function of the measure of the bit wear is the difference between unity and a constant of proportionality times a power of the measure of the bit wear.
The method of claim in which the rate of change of the measure of the bit wear is estimated as proportional to the rock strength.
The method of claim in which the rate of change of the bit wear is estimated as proportional to the weight on bit.
A method of drilling a well or fracturing a formation drilled by a well, the method comprising the steps of:
- drilling through rock with a drilling system by rotating a bit;
- providing a model for calculating rate of penetration of the bit through the rock being drilled through, the model including the strength of the rock and known or estimated parameters, the known or estimated parameters including an estimate of a hydraulic level;
- measuring or estimating a value of the rate of penetration of the bit;
- estimating the strength of the rock according to a value of the strength of the rock required to cause the model to calculate the rate of penetration of the bit to have the measured or estimated value given the known or estimated parameters;
- and
- setting drilling or fracturing parameters according to the estimated rock strength.
A method of drilling a well or fracturing a formation drilled by a well, the method comprising the steps of:
- drilling through rock with a drilling system by rotating a bit;
- providing a model for calculating the mechanical specific energy of the rock being drilled through, the model including a rate of penetration of the bit, a wear function of the bit and a hydraulic efficiency of the bit;
- measuring or estimating a value of the rate of penetration of the bit, a value of the wear function of the bit and a value of the hydraulic efficiency of the bit;
- estimating the mechanical specific energy by applying the model to the measured or estimated value of the rate of penetration of the bit, value of the wear function of the bit and value of the hydraulic efficiency of the bit;
- and
- setting drilling or fracturing parameters according to the estimated mechanical specific energy.
Dependencies are inferred from the claim text.