Improved optimization of drilling bit selection and the compatibility between drilling bit and formation constraint the ROP and cost of deep well drilling to some extent. This combined with lab comprehensive lab drilling simulations and mechanisms of rock penetration can hold promise for improving drilling efficiency in deep wells. This paper reviews the mechanical characteristic parameters of rock engineering and demonstrates the obstacle of rock penetration in deep wells. Based on the general predictable formula of ROP, the relationship between drilling sensitive index and formation drillability is analyzed and the optimization and optimal match of drilling technology parameters are described. Technology Benefit Index (TBI) is proposed to evaluate the technical performance of drilling bit, advices and warnings from lab experiment and field experience on selecting and using bit are put forward. Statistical analysis of Well A based on TBI is made, the analysis of ROP improvement potential and overall program (including Bottom Hole Assembly, drilling parameters and type of drilling bit) of ROP improvement for Well B are worked out. Suggestions of drilling bit using based on mechanisms of rock penetration are proposed. Guided by the theory on improving ROP field tests of improving drilling rate are conducted to examine the field performance. By comparison, the tested sections yield high performance of ROP improvement. The designed program enhancing ROP for experiment section proves to be operable and shows great promise in further improvement and application.

With the development of deep well drilling technology, a new HTHP (High Temperature High Pressure) experimental apparatus LH-1 was developed to meet the need of research and evaluation of deep well drilling fluid. With the advanced dynamic seal technology, mechanical transmission and data sensing technology, this new apparatus has many kinds of HTHP testing functions in a body and could evaluate manifold performances at the dynamic state of high temperature and high pressure including HTHP dynamic or static filtration test, high temperature dynamic scattering test of drilling cuttings, HTHP dynamic sealing and plugging tests, ultra HTHP aging test and so on. The lab tests show that the new apparatus gains such advantages as novelty of the design, stability of the performance, accuracy and reliability of the experimental data and facility of the operation. Having overcome the defections of the old apparatuses, the new device can provide a new means of experimental researches for the evaluation of HTHP comprehensive performance of deep well drilling fluid.