Volume one of this two-volume set covers historical trends and two major aspects of drilling technologies—downhole motors and oil well drilling optimization (KTW—Key Technological Wells drilling method) Unlike the U.S. and other countries, which use rotary drilling, the Russians use downhole hydraulic and electrical motors that power the bit downhole. Using a downhole motor is more efficient, especially in hard formations. Advanced drilling studies have long been conducted in the FSU and are important in reducing drilling costs in marginal reservoirs. This technology is beginning to gain popularity in the U.S. and other countries.