Highly oscillatory flow regimes that can occur in gas-lift oil wells have been successfully treated using conventional linear control. However, these control systems rely on downhole pressure measurements which are unreliable or even unavailable in some cases. In this paper we propose a solution based on a high gain observer for the state of the process. The estimates are used to compute the do...

In underbalanced drilling (UBD), the bottom hole pressure is kept below pore pressure, causing pressure-dependent influx of reservoir gas into wellbore that makes system unstable at low drawdowns. this article, we propose a feedback controller which stabilizes system, represented by “reduced drift flux model (DFM),” around an arbitrary setpoint, while using only topside measurement and assuming...

Abstract Stress state is a long-sought but poorly known parameter on subduction megathrusts and in overlying accretionary wedges general. We used direct observations made during drilling of Integrated Ocean Drilling Program (IODP) borehole C0002 to depth 3058 m below the seafloor (mbsf) Nankai zone southwestern Japan constrain situ pore pressure stress deep interior an wedge for first time. The...

The process of borehole drilling is a nonlinear and many dimensional process. During drilling it is possible occurrence of some complications (for example transition of drilling tool in layer with anomalous pressure). New method of identification of rock layers with anomalous pressure was proposed and tested on real plant data.

Abstract Rapid Access Ice Drill is a new drilling technology capable of quickly accessing the glacial bed Antarctic ice sheets, retrieving core and rock samples, providing boreholes for downhole logging physical properties. Scientific goals include searching old near sampling subglacial bedrock. During field trials McMurdo Station on piedmont glacier at Minna Bluff in 2019–20 austral summer, we...

Abstract Lake Towuti is located on central Sulawesi/Indonesia, within the Indo Pacific Warm Pool, a globally important region for atmospheric heat and moisture budgets. In 2015 Drilling Project recovered more than 1000 m of drill core from lake, along with downhole geophysical logging data two drilling sites. The cores constitute longest continuous lacustrine sediment succession Pool. We combin...

This paper explores the theory and potential of a family of reluctance motors as well as brief review of different types of reluctance motors, motivated by the increased demands for geometric versatility and ruggedness for electric motors. This paper presents a new and novel disc type reluctance motor that has been designed built, tested, and analyzed. The magnetic circuit-based analysis shows ...

permanent magnet synchronous motors are efficient motors, which have widespread applications in electric industry due to their noticeable features. one of the interesting applications of such motors is in underwater vehicles. in these cases, reaching to minimum volume and high torque of the motor are the major concern. design optimization can enhance their merits considerably, thus reduce volum...

Summary During drilling operations, drillstring vibrations cause many downhole dysfunctions, resulting in underperformance, equipment failure, and possibly wellbore damage. Current vibration mitigation solutions are generally located at a single site, either the topdrive or close to bit. However, because sources of excitation distributed along whole drillstring, these single-point damping do no...

New downhole turbine generator can transmit the high speed rotation of the turbine to the rotor of the generator without contact by magnetic transmission mechanism to provide continuous power. Driving torque on magnetic transmission mechanism is a key parameter. This paper mainly studies the field on magnetic transmission mechanism of downhole turbine generator by using ANSYS software. The effe...