Drilling process and apparatus
First Claim
1. A drilling process comprising urging a rotating drill bit towards a mass to be drilled, and controlling the thrust applied and the speed of rotation, the process comprising monitoring at least one parameter selected from controlled parameters including rate of penetrating of the drill bit and wear rate of the drill bit, and adjusting at least one related variable selected from adjustable variables including rate of rotation of the drill bit and thrust applied to the drill bit so as to bring the controlled parameters to operating values at which the cost of drilling per unit depth is substantially minimized.
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Accused Products
Abstract
In a drilling process speed, bit thrust and penetration are monitored. Data stored in a data base relating rotational speed and thrust as adjustable variables is correlated with data on the penetration rate as controlled parameter to produce a matrix to enable prediction of penetration rate to be expected at known thrust and rotational rates. Likewise a similar matrix may be constructed for relating wear rate to adjustable variables for example speed and thrust. The parameters predicted from these variables at various values for the speed and thrust are used to construct a further matrix relating bit penetration and bit wear rates with cost per unit distance drilled and this third matrix searched for minimum cost. From the first two matrices rotation rate of the drill bit and thrust applied to the drill bit are adjusted to give a predicted penetration rate for minimum cost and the drill bit is operated at these conditions. All conditions are monitored and the information used to recalculate the various matrices to define the process.
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Citations
14 Claims
- 1. A drilling process comprising urging a rotating drill bit towards a mass to be drilled, and controlling the thrust applied and the speed of rotation, the process comprising monitoring at least one parameter selected from controlled parameters including rate of penetrating of the drill bit and wear rate of the drill bit, and adjusting at least one related variable selected from adjustable variables including rate of rotation of the drill bit and thrust applied to the drill bit so as to bring the controlled parameters to operating values at which the cost of drilling per unit depth is substantially minimized.
- 4. A drilling process comprising establishing a first matrix storing known data relating variables selected from adjustable variables including rotation rate of a drill bit and thrust applied to a drill bit, to a first parameter selected from controlled parameters including bit penetration rate and bit wear rate, and using the known data points to interpolate predicted values for the first controlled parameter for other values of the adjustable variables, establishing a second matrix storing known data relating the first parameter and a second control parameter to a third parameter, and using the known data points to interpolate predicted values for the third parameter for other values of the first and second controlled parameters, searching the second matrix for an optimum value of the third parameter and thereby determining optimum values for the first and second parameters and adjusting the adjustable variables to the value indicated by the first matrix to be necessary to achieve the determined optimum value for the first control parameter.
Specification