Waterway control assembly for rope core drilling rig and its application method

In the process of conventional rope core drilling, the connection and disassembly of waterway occupy a lot of auxiliary time, which seriously affects the drilling efficiency, and even causes drilling or safety accidents. The waterway control assembly and application method for the rope coring rig developed by the author’s team can control the waterway flow direction. It does not need to disassemble the water pipe frequently to control the raising speed of the inner pipe and avoid damaging the drilling tool too fast.Introduction.

Successful Application of Managed Pressure Drilling and Cementing in Naturally Fractured Carbonates Environment of Prohorovskoe Exploration Well

This technical paper provides the result of utilizing MPD technology for drilling and cementing a 127 mm production liner withing the Zadonian horizon D3zd in an exploratory well of the Prohorovskoe field. The previous wells drilled with a conventional approach in the field had complicated issues such as circulation losses and well control. It was complexified with high hydrogen disulfide concentration in reservoir oil which was a health hazard to a site personnel. As a result, to eliminate all complications, resources and operational time were needed. To prevent and eliminate complications in a long wall, core drilling and well completion, managed pressure drilling (MPD) and cementing technology with semi-automatic control system was applied. The project is unique as such complicated jobs with the core drilling and cementing with MPD were executed for the first time in The Komi Republic. MPD approach allowed to figure out bottomhole safe conditions and maintain ECD within a required pressure window. It is necessary to notice that a part of the section was core drilled. Knowing the window between pore and fracture pressures safety limits, a run-in-the-hole design with further cementing job was optimized. The execution was done flawlessly without circulation losses and well control issues. In comparison to a previous well in the Prohorovskoe field, MPD allowed to shorten loss circulated mud volume from 2 2215 m3 to 0 m3 and avoid non-productive time. Through accomplished goals and lessons learned, new grounds to well owners and well services in a field development stage are broken.

Assessment of organic carbon contamination in the unsaturated zone: a case of Yogyakarta City, Indonesia

In 1997, groundwater pollution was caused by a diesel leak at the Yogyakarta City Railway Station. People in the south of the railway station discovered the presence of diesel in dug wells in 2001. The existing diesel is still found in dug wells even though the pollutant source had been removed. The current source of pollution comes from diesel residues trapped in the unsaturated zone. Understanding the distribution and concentration of diesel in the unsaturated zone is the goal of this study. In this study, diesel concentration was measured based on Total Organic Carbon (TOC) levels. The research was conducted through shallow core and deep core drillings. Shallow core drilling was done at 14 points with a depth of 50 cm, and deep core drilling was done at nine drilling points with a depth of 15-17 m. 14 shallow core drilling samples were taken from a depth of 30 and 50 cm and nine deep core drilling samples were taken from a depth of 4-5 m and 10-11 m. The lithology logs in both drills were tested for diesel odour and TOC levels using the Soli TOC tool. Based on the test results, the smell of diesel was found at a depth of 10 to 15 m. TOC levels in the unsaturated zone ranged from 340 to 90,870 mg/L. TOC levels >30,000 mg/L were dominant at shallow depths even though they did not smell like diesel. At a location close to the source of the diesel tank leak at a depth of 4-5 m, the measured TOC level was 30,100 mg/L. The results showed that there were zones of high TOC levels associated with diesel odour layers. The zones existed because of the infiltration and percolation processes that had carried surface water and diesel pollutants and eventually moved horizontally following groundwater flow.

Ice core drilling on a high-elevation accumulation zone of Trambau Glacier in the Nepal Himalaya

We drilled an 81.2-m-long ice core in the accumulation area (5860 m a.s.l.) of Trambau Glacier in the Rolwaling region during October–November 2019. The drilling operation was conducted with a lightweight electro-mechanical drill system after two reconnaissance fieldworks in 2017 and 2018, during which two shallow firn cores were drilled with a hand auger. The drill system and ice core samples were transported by helicopters at a high elevation of 6000 m a.s.l. A further challenging issue was the ice core transportation between Nepal and Japan, as no regular commercial flight was available for the frozen samples. The addition of dry ice imported from India immediately prior to leaving Nepal allowed the ice core samples to be successfully transported to a cold room in Japan, and remain in a frozen state. Stratigraphic observations during the drilling operation suggest the drill site has been affected by melting and refreezing.

Investigation of the Strength Parameters of Drilling Pumps during the Formation of Contact Stresses in Gears

The relevance of this research lies in the need to develop scientifically based methods for calculating and designing a transmission shaft with a hardened coating of increased strength and service life of a core drilling pump drive that can allow for a redistributing of resistance forces along the contact surfaces of the gear. This relevance is confirmed by the need to improve domestic methods for designing drive shafts of increased reliability which can ensure the development of frozen soils during deposits exploration. The purpose of the research is to increase the energy efficiency and service life of the high-loaded drive gear teeth of core drilling pump transmission shafts by justifying the critical loads and stresses in hardened gear coatings acting under intense wear of the contact surface with a broken contact symmetry. The criteria for the effective wear area with an uneven contact cross-section at the maximum bending moments of the transmission shaft of the drilling pump were justified and presented in the work. Additionally, the process of interaction of the transmission shaft gear teeth with the eccentric shaft gear at uneven axial torques was investigated. The effective power (Ng) of the gearing of the drive transmission shaft gear and the eccentric shaft gear, which characterizes the energy consumption of the drill bit depth stroke, was justified. This work also proposes a method of substantiating the technological and power parameters of the transmission shaft by using Legendre polynomials. A nomographic chart was developed for the determination of the dependence of the contact stress base cycles on the change in the load distribution factor and the contact spot deviation factor from the design axis λ.