What has been achieved in China's oil & gas industry?

Continuous improvements have been achieved in technical performance indicators such as the drilling cycle, ROP and other metrics. Over 200 wells successfully drilled with MD exceeding 8000m have enabled China to normalize 8000m ultra-deep onshore drilling, with drilling capacity reaching 9000m.

Does rotary non-percussive drilling cause rock failure?

According to the analysis on the SE values at different drilling conditions in rotary non-percussive drilling, the rock failure before the bit is more related to rotary shear than the axial force. Table 2. Calculation of SE based on different drilling parameters in the field test.

Can China normalize 8000m ultra-deep onshore drilling?

Over 200 wells successfully drilled with MD exceeding 8000m have enabled China to normalize 8000m ultra-deep onshore drilling, with drilling capacity reaching 9000m. Moreover, the well depth of TK-1 has successfully exceeded 10000m, making China the second country in the world to successfully drill onshore vertical well with the depth over 10000m.

Does high ROP imply high drilling efficiency in practical engineering?

Note that high ROP does not imply high drilling efficiency in practical engineering because high ROP accelerates the wear of the drilling bit, thereby prolonging the drilling time. Furthermore, the drilling operators possess a few constraints in selecting the correct ROP parameters to optimize the drilling efficiency.

Why do drilling operators need a new index based on rock properties?

However, drilling operators always change drilling parameters to achieve higher drilling efficiency. Hence, a new index that is only related to rock properties and can be successfully applied under different drilling conditions should be developed to define rock properties.

How does cutting a well affect drilling efficiency?

Excessive cuttings will make it difficult to carry drilling fluid, resulting in the deposition of cuttings at the bottom of the wellbore, and the repeated crushing of the rock at the bottom of the wellbore will affect the drilling time and thus reduce the drilling efficiency.