Publications

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

This report provides an assessment of well construction technology for EGS with two primary objectives: 1. Determining the ability of existing technologies to develop EGS wells. 2. Identifying critical well construction research lines and development technologies that are likely to enhance prospects for EGS viability and improve overall economics.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

This report describes a project to develop technology to integrate passively pulsating, cavitating nozzles within Polycrystalline Diamond Compact (PDC) bits for use with conventional rig pressures to improve the rock-cutting process in geothermal formations. The hydraulic horsepower on a conventional drill rig is significantly greater than that delivered to the rock through bit rotation. This project seeks to leverage this hydraulic resource to extend PDC bits to geothermal drilling.

Our charter at Sandia National Laboratories is to develop technology to reduce the development cost of geothermal drilling. Due to their aggressive penetration rate performance, Polycrystalline Diamond Compact (PDC) bits are of particular interest for this application and they have recently been demonstrated to be capable of drilling hard-rock formations characteristic of geothermal reservoirs. Additionally, oil and gas operators are increasingly forced to extend their drilling targets to include these hard-rock formations as our fossil energy reserves dwindle. However, PDC bits are particularly susceptible to impact-type damage due to the onset of drilling vibrations that can cause bit failure. Bit vibration produces an undulated surface in the rock that in turn produces a time-variant force that feeds back into the vibration of the bit and drillstring. While there is considerable debate in the drilling community regarding the relative significance of the various types of vibrations, self-induced vibrations do occur and can be mathematically predicted if the drill bit, drillstring, and rock type are not correctly matched. One way to alleviate this problem is to insert a vibration absorber into the drillstring. Given the broad range of parameters contributing to bit vibrations, any damper installed in the drillstring should be controllable to give it more dynamic range. We have experimentally demonstrated that a controllable damper can introduce stability in PDC bits drilling hard rock typical of geothermal formations.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Typical laboratory testing of Polycrystalline Diamond Compact (PDC) bits is performed on relatively rigid setups. Even in hard rock, PDC bits exhibit reasonable life using such testing schemes. Unfortunately, field experience indicates otherwise. In this paper, the authors show that introducing compliance in testing setups provides better simulation of actual field conditions. Using such a scheme, they show that chatter can be severe even in softer rock, such as sandstone, and very destructive to the cutters in hard rock, such as sierra white granite.