Shen Zhonghou

Investigation and application of self-resonating cavitating water jet in petroleum engineering

Abstract The paper presents the investigations of a unique jet as self-resonating water jet including the modulating principles, characteristics of impact pressure and rock erosion, and field applications in petroleum engineering in China. The research showed that jet nozzles designed with organ pipe structure could generate significant self-resonating cavitating water jets. As compared with conventional cone-shaped nozzle with 120° taper angle, the amplitudes of pressure fluctuation and maximum impact pressure of self-resonating cavitating water jets increase by 24 and 37%, respectively, and rock erosion efficiency increases by 1 to 2 times. Self-resonating water jets have been successfully applied in petroleum drilling engineering, with enhanced average rates of penetration of tricone bits by 31.2% and improved bit footages by 29.1%. Treatment of near wellbore formation and self-excited oscillating water injection with self-resonating water jets have resulted in economic efficiency.

Influences of formation water invasion on the wellbore temperature and pressure in supercritical CO2 drilling

Abstract Aiming to study the influence of formation water invasion on the wellbore temperature and pressure in SC-CO2 (supercritical CO2) drilling with coiled tubing, this paper builds up a wellbore flow model with formation water invasion in SC-CO2 drilling with coiled tubing, based on the comprehensive investigation of the influence of viscosity, density, thermal conductivity, isobaric heat capacity and Joule-Thompson coefficient of SC-CO2. The wellbore temperature and pressure distribution were calculated by the method of coupling among these parameters. The results show that the bigger the rate of invaded formation water and the bigger the density of mixed fluid, the bigger the convective heat transfer coefficient in the annulus. Because of the Joule-Thompson cooling effect caused by nozzle throttling, the annulus Mixed fluid density increased abruptly and the convective heat transfer coefficient decreased abruptly at the well depth of about 1 900 m (about 100 m to bottom hole). Meanwhile the wellbore fluid temperature increased with the invasion rate of formation water, and the same Joule-Thompson cooling effect caused the wellbore fluid temperature to decrease abruptly at the well depth of about 1 900 m. Moreover, the wellbore annulus pressure increased with the increasing of invaded formation water quantity. But the amplitude is not obvious.

CURRENT STATUS AND FUTURE PROSPECTS OF WATER JET TECHNOLOGY IN PETROLEUM ENGINEERING IN CHINA

ABSTRACT This paper reviews the developments of investigation and application of high pressure water jet technology in both deep drilling and oil production including jet-bit drilling, extended nozzles and their combination to enhance hydraulic effectiveness at bottomhole, combined jet and mechanical drilling, new efficient jets (self-resonating cavitating jet, self-excited oscillation jet, swirling jet) used in drilling, horizontal well drilling by water jet, near wellbore plug removal with water jet, and high pressure water jet penetrating. Laboratory investigation and field application have coherently shown that high pressure jet drilling can increase the penetration rate. The hydraulic power of rock bit with extended nozzles and with crossflow hydraulics can increase by 30∼40 percent, the bit footage by 40 to 50 percent and dynamic pressure by 90 to 110 percent compared with conventional bit. Combined jet and mechanical drilling can increase drilling rate by a factor of 3 in deep wells than convention...