Patent ID: 7991554

Claim:
A method implemented by a processor of a computing device for predicting the rate of drilling of a well bore in a subterranean formation, the method comprising the steps of: A) determining by the processor the rate of penetration (ROP) of a drill bit drilling a well bore through intervals of rock of a subterranean formation by: a) determining for at least one type of drill bit a relationship between a bit-specific coefficient of sliding friction μ and confined compressive strength CCS over a range of confined compressive strengths CCS; b) determining for the at least one type of drill bit a relationship between mechanical efficiency EFF M and confined compressive strength CCS over a range of confined compressive strengths CCS; c) determining the confined compressive strength for intervals of rock through which the at least one type of drill bit is to be drilled to form a well bore, the determination of the confined compressive strength based at least in part on an unconfined compressive strength of the intervals; and d) calculating the rate of penetration ROP for the at least one type of drill bit drilling along the intervals of rock to create a well bore, the calculations utilizing the confined compressive strength of the intervals of rock being drilled and the relationships between the bit-specific coefficient of sliding friction μ and the mechanical efficiency EFF M and the confined compressive strengths CCS; and B) predicting the rate of drilling based on the calculated rate of penetration ROP.