Icelandia

ABSTRACT We propose a new, sunken continent beneath the North Atlantic Ocean that we name Icelandia. It may comprise blocks of full-thickness continental lithosphere or extended, magma-inflated continental layers that form hybrid continental-oceanic lithosphere. It underlies the Greenland-Iceland-Faroe Ridge and the Jan Mayen microplate complex, covering an area of ~600,000 km2. It is contiguous with the Faroe Plateau and known parts of the submarine continental rifted margin offshore Britain. If these are included in a “Greater Icelandia,” the entire area is ~1,000,000 km2 in size. The existence of Icelandia needs to be tested. Candidate approaches include magnetotelluric surveying in Iceland; ultralong, full-crust-penetrating reflection profiling along the length of the Greenland-Iceland-Faroe Ridge; dating zircons collected in Iceland; deep drilling; and reappraisal of the geology of Iceland. Some of these methods could be applied to other candidate sunken continents that are common in the oceans.

Analysis of the deep drilling technology in unstable formations at the Semyrenky gas condensate field

The paper presents a general overview of deep drilling in unstable formations at the Semyrenky gas condensate field of the Dnipro-Donetsk Trough, including well design, bottom hole assemblies (BHA), drilling conditions, and drilling muds. Problems encountered during drilling for production casing of Wells 72- and 75-Semyrenky using high-speed drilling methods are analyzed. The relationships between the rate of penetration and disturbed rock stability, volume excess and depth, as well as consistent empirical patterns in changes in mud properties and depth are established. With these technical and economic performance indicators for well drilling are given, elements of a borehole stability management strategy were defined, the principles of mud selection for drilling through problem zones are validated. The paper discusses the requirements to a mud hydraulics program to reduce the erosion of borehole walls, specific borehole preparation techniques, such as reaming and gauging, for drilling in problem zones, and alternative options to ensure borehole stability. Keywords: borehole stability; statistical models; hole gauging; hole geometry; drilling mud; BHA.

FINITE ELEMENT ANALYSIS OF TOOLS FOR DEEP DRILLING TECHNOLOGY

Using the ANSYS software package, the issues of strength of the drill head and temperature distribution were considered, the design of a modern tool for deep hole drilling was analyzed, and modal analysis was carried out to exclude possible resonance phenomena.

Improvement of Rheological and Filtration Properties of Water-Based Drilling Fluids Using Bentonite-Hydrothermal Carbon Nanocomposites Under the Ultra-High Temperature and High Pressure Conditions

With the depletion of the conventional shallow oil/gas reservoirs and the increasing demand for oil and gas, deep drilling become more and more essential to extract the oil/gas from deep formations. However, deep drilling faces many complex challenges. One of the complexities is the degradation of polymers and flocculation of bentonite particles, leading to hardly control the rheological and filtration properties of water-based drilling fluids, especially under ultra-high temperature and high pressure (HTHP) conditions. Therefore, an experimental investigation is performed to study how bentonite-hydrothermal carbon nanocomposites will influence the rheological and filtration properties of water-based drilling fluids under ultra-HTHP conditions. Bentonite-hydrothermal carbon nanocomposites are proposed as non-polymer additives to solve the ultra-HTHP challenge in water-based drilling fluid. The nanocomposites are synthesized by facile hydrothermal reaction, in which biomass starch and sodium bentonite are used as the precursor and template, respectively. In this study, the effect of the nanocomposites on the rheology and filtration properties of water-based drilling fluid are investigated before and after hot rolling at 220 °C and 240 °C. The structure characterization indicates that carbon nanospheres can successfully deposit on the bentonite surface after hydrothermal reaction and finally form as nanocomposites. The elemental carbon content, zeta potential and particle size distribution of the nanocomposites could be adjusted according to the reaction conditions. After thermal aging at 220 °C and 240 °C, addition of nanocomposites can improve the rheological properties significantly where a stable and minor change of rheological properties is observed, which is desirable for ultra-HTHP drilling. Regarding filtration control, after adding 1.0 wt% nanocomposite materials, the filtration loss is reduced by 41% and 44% respectively after aging at 220 °C and 240 °C, which is better than the conventional natural materials that lose their function in this case. The identification of microstructure shows that the hydrothermal reaction endows nanocomposites with a unique surface morphology and an improved surface charge density. The interaction between nanocomposites and bentonite particles forms a rigid connection network, which is the main mechanism to facilitate effective rheology and filtration control under ultra-HTHP conditions. The green and facile synthetic routes and environmentally friendly features of the nanocomposites, coupled with the excellent performance in ultra-HTHP rheology and filtration control, indicate that the nanocomposites have a high promise for water-based drilling fluid in ultra-HTHP drilling. Moreover, it provides a new way to design high performance additives with high temperature stability.

Nano-Materials Modified Drilling Fluid for Improving Deep Drilling Conditions

Achieving stability of drilling fluids (DFs) rheology with high temperature and pressure (HTHP) has always seen a growing focus with increasing pursuits of deep drilling operations to maximize hydrocarbon recovery. Since, there is no boundary of how deep the drilling technology can be pushed to access deep lying reservoirs, the quest to improve and stabilize the drilling fluids rheology is an open-ended and ongoing matter. This paper presents an investigation of two distinct clays namely sepiolite (SP) and attapulgite (AT) in nano-form as water-based drilling fluid (WBDF) additives for improved and stable rheological properties. The process of material sourcing, characterization, development in nano-form and testing as a drilling fluid additive at low and high temperature and pressure conditions are the main focus of this study. Through experiments it was determined that 30-60nm size range and 4wt% concentration of developed nano-materials yielded the optimal performance. Various tests were then performed at HTHP and the stability of nano-sepiolite (NSP) and nano-attapulgite (NAT) in 4wt% concentration was compared with regular drilling fluid additive (bdf403) which is used as a common rheology stabilizer in the industry. It was found that for NSP and NAT modified drilling fluids, the yield point, plastic viscosity, and gel strength were found to be retained at temperatures and pressures of up to 180 °C and 15 ksi, respectively, in contrast to bdf403 WBDF which deteriorated at much lower temperature and pressure. NSP additives were found to be more effective than NAT additives. The results confirmed a strong dependence of the DF stability on the morphological characteristics of the tested clays, implying that the properties of the DFs can be tailored by modifying the clay morphologies, particularly in the nanoform.

THE USE GUIDED DRILLING PIPES FOR VARIOUS PURPOSES

The proposed installation provides control and monitoring of the parameters of the cutting tool during deep drilling of pipes for various purposes due to the controller and sensors, which are mounted on special equipment designed for processing deep holes. Installed sensors control such parameters as tool rotation, feed, part rotation, runout on the outer surface of the part, and the wall thickness of the part during processing. Movement of the cutting tool of the drilling head, in which a sensor for monitoring the thickness difference is installed using a lubricating and cooling liquid supplied to the head as a contact medium, which ensures the operation of the sensor for monitoring the wall thickness. The controller processes the data received from all sensors, and sends a pulse signal, thereby making appropriate adjustments to the operation of the entire installation.