Deep Drilling Operations Research Articles

New stratigraphic interpretation of the Soultz-sous-Forêts 30-year-old geothermal wells calibrated on the recent one from Rittershoffen (Upper Rhine Graben, France)

The Soultz-sous-Forets site (Alsace, France) is the first pilot geothermal project in the world that furnished the proof of concept of enhanced geothermal systems by producing energy from a deep-seated granite. The Alsace region, with its hundreds of previous drillings and seismic history related to both oil and potash exploitation, has been shown to have high subterranean temperatures. In the Soultz-sous-Forets geothermal project, most attention has focused on the basement and the sedimentary cover/basement interface. Thus, the sedimentary portion of the well (approximately 1.4 km thick) has never been fully investigated. The only available data on the Soultz-sous-Forets sedimentary cover are from an old masterlog (GPK-1) with interpretations of the tops and bases of the main geological formations, and from some other less well-documented well logs (EPS-1 and GPK-2). The main challenge of this work is therefore to re-interpret the old well data to provide precise and detailed chrono-lithostratigraphic logs for GPK-1 and GPK-2, especially in their sedimentary portions. These new investigations of the GPK wells have been possible due to the new data collected in the recent geothermal wells at Rittershoffen (GRT-1 and GRT-2, located 6.5 km from Soultz-sous-Forets), which are characterized by a quite complete stratigraphic succession. Both sites have been explored by deep drilling operations aiming to exploit the heat extracted from a deep granitic basement (Palaeozoic) covered by a stack of 1.4- and 2.2-km-thick sedimentary rocks (Mesozoic to Cenozoic) at Soultz-sous-Forets and Rittershoffen, respectively. Thus, the Rittershoffen chrono-lithostratigraphic logs have been used as a baseline to interpret the sedimentary succession in GPK-1 and GPK-2. In conclusion, all the well logs are compared for stratigraphic comparisons. With approximately 1400 m of sedimentary cover at Soultz-sous-Forets instead of 2200 m at Rittershoffen, the correlation between the two sites showed many differences exist in the sedimentary columns: layers missing due to erosion, lateral thickness variations in formations, and—above all—the occurrence of at least four major fracture zones affecting the units. In addition, a structural analysis was made to more precisely define the limits of the geological formations observed and to present more arguments for the presence of fracture zones or faults.

Study on tool wear and chip shapes in deep drilling OF AISI 4150 steel

Deep drilling process is widely used in the manufacturing of diesel injection components such as the injection holder, used to transport fuel from the high-pressure pipe to the combustion chamber of the engine. The material used in the manufacturing of these components is low-alloy steel AISI 4150. This high percentage chrome (~1 %) and molybdenum (~0.2 %) steel attains its high resistance through heat treatment (quenching and tempering), which allows this material for working with high injection pressures up to 2300 bar. However, it presents problems in deep drilling operations. This is due to the high rate of drill bit breakage, high tool wear and ribbon-like chips. This work studies deep drilling of AISI 4150 steel by analyzing through the method of design of experiment, the influence of the following machining factors: cutting speed, feed-rate and tool coating. Tool wear, machining drilling torque and shape of the machined chips were considered for the analysis. Evidences were found that the uncoated tool shows a cyclical wear mechanism of adhesion removal workpiece material on the tool, where material is welded onto the cutting edge forming the built-up edge. The results showed that TiNAI-coated tool did not present this wear mechanism and it outperformed the uncoated tool.

Effect of Cutting Speed and Feed on Deep Drilling

The article describes the deep drilling tests of internal company research, which is aimed to determine the geometric tolerances as run-out, roundness and roughness, but also the shape and size of chips depending on cutting parameters. Further exploration subject was recorded using the actual engine power to determine the torque and axial force required for removing particles at the given cutting parameters. The results served to increase the productivity of deep drilling operations within the optimization process.

The Consequence of Stress Intensity on Faigue Crack Propagation in High-Strength Steels in Sour Environmet

The Unites States predicted a significant growth in energy demand by 2030 makes oil and natural gas primary target fuels for energy generation.1The peak of oil production from shallow wells (< 5000 m) is about to be reached and has pushed exploration for oil and natural gas into deeper reservoirs. However, drilling to depths greater than 5000 m requires increasing the strength-to weight ratio of the drill pipe materials. Grade UD-165 is one of the ultra- high yield strength carbon steels developed for ultra deep drilling (UDD) activities.Drilling UDD wells exposes the drill pipes to Cl-, HCO3 -/CO3 2-, and H2S-containig corrosive environments (i.e., sour environments) at higher pressures and temperatures compared to those found in conventional wells. Approximately 75% of all drill string failures are caused by fatigue or corrosion fatigue2. To avoid catastrophic failures of drill string candidate alloys, NETL in collaboration with DNV, has been conducting research on the fatigue crack growth (FCGR) behavior of the ultra- high yield strength carbon steels, e.g., grade UD-165, which was developed for ultra deep drilling (UDD) operations in sour well environments.3 The FCGR behavior of ultrahigh -strength carbon steel, grade UD-165, was investigated by monitoring crack growth rate in deaerated 5%NaCl solution buffered with NaHCO3/Na2CO3 and in contact with H2S. The partial pressure of H2S (pH2S) was 0.83 kPa and pH of the solution was 7. The fatigue experiments were performed on ½T-CT specimens at 20°C at a stress ratio (R) of 0.13 and stress intensity factors (ΔK) of 219.8 and 153.5 MPa√cm, respectively, in an autoclave with surface investigations augmented by scanning electron microscopy (SEM), elemental x-ray mapping and energy dispersive x-ray (EDX) spectroscopy. Research focused on understanding the influence of environment on crack growth rate by examining the crack path in exposed specimens.Samples in this study failed catastrophically along the crack after they were removed from the autoclave. Figure 1shows a secondary (SE) SEM micrograph of the fracture surface after the FCGR testing at ΔK=219.8 MPa√cm. It appears that the failure mode is transgranular. Also, few pits are observed on the fracture surface.Fig. 1. Microfractograph of UD-165 after a fatigue test at ΔK=219.8 MPa√cm in NaCl/NaHCO3/Na2CO3/pH2S = 0.83 kPa at 20°C, pH=7.The micrograph of the fracture surface sample after the fatigue test at ΔK=153.5 MPa√cm under sour conditions with pH=7 at 20°C, Fig. 2, looks different from that surface tested at ΔK=219.8 MPa√cm in the same solution.Fig. 2. Microfractograph of UD-165 after a fatigue test at ΔK=153.5MPai√cm in NaCl/NaHCO3/Na2CO3/pH2S = 0.83 kPa at 20°C, pH=7.Relatively dense corrosion products covered relatively large areas of the sample. Around these crystalline-like structure is observed. The latter is characteristic of intergranular failure.It appears that at 219.8 MPa√cm , fracture is mainly transgranular, while at 154.5MPa√cm an intergranular fracture is the primary mode of failure.

The EPICA Dronning Maud Land deep drilling operation

AbstractWe report on the EPICA Dronning Maud Land (East Antarctica) deep drilling operation. Starting with the scientific questions that led to the outline of the EPICA project, we introduce the setting of sister drillings at NorthGRIP and EPICA Dome C within the European ice-coring community. The progress of the drilling operation is described within the context of three parallel, deep-drilling operations, the problems that occurred and the solutions we developed. Modified procedures are described, such as the monitoring of penetration rate via cable weight rather than motor torque, and modifications to the system (e.g. closing the openings at the lower end of the outer barrel to reduce the risk of immersing the drill in highly concentrated chip suspension). Parameters of the drilling (e.g. core-break force, cutter pitch, chips balance, liquid level, core production rate and piece number) are discussed. We also review the operational mode, particularly in the context of achieved core length and piece length, which have to be optimized for drilling efficiency and core quality respectively. We conclude with recommendations addressing the design of the chip-collection openings and strictly limiting the cable-load drop with respect to the load at the start of the run.

Using artificial intelligence to predict surface roughness in deep drilling of steel components

A predictive model is presented to optimize deep drilling operations under high speed conditions for the manufacture of steel components such as moulds and dies. The input data include cutting parameters and axial cutting forces measured by sensors on the milling centres where the tests are performed. The novelty of the paper lies in the use of Bayesian Networks that consider the cooling system as an input variable for the optimization of roughness quality in deep drilling operations. Two different coolant strategies are tested: traditional working fluid and MQL (Minimum Quantity Lubrication). The model is based on a machine learning classification method known as Bayesian networks. Various measures used to assess the model demonstrate its suitability to control this type of industrial task. Its ease of interpretation is a further advantage in comparison with other artificial intelligence tools, which makes it a user-friendly application for machine operators.

A soft computing system using intelligent imputation strategies for roughness prediction in deep drilling

A soft computing system used to optimize deep drilling operations under high-speed conditions in the manufacture of steel components is presented. The input data includes cutting parameters and axial cutting force obtained from the power consumption of the feed motor of the milling centres. Two different coolant strategies are tested: traditional working fluid and Minimum Quantity Lubrication (MQL). The model is constructed in three phases. First, a new strategy is proposed to evaluate and complete the set of available measurements. The primary objective of this phase is to decide whether further drilling experiments are required to develop an accurate roughness prediction model. An important aspect of the proposed strategy is the imputation of missing data, which is used to fully exploit both complete and incomplete measurements. The proposed imputation algorithm is based on a genetic algorithm and aims to improve prediction accuracy. In the second phase, a bag of multilayer perceptrons is used to model the impact of deep drilling settings on borehole roughness. Finally, this model is supplied with the borehole dimensions, coolant option and expected axial force to develop a 3D surface showing the expected borehole roughness as a function of drilling process settings. This plot is the necessary output of the model for its use under real workshop conditions. The proposed system is capable of approximating the optimal model used to control deep drilling tasks on steel components for industrial use.

Ultradeep Drilling Pushes Drillstring Technology Innovations

Summary Drilling ultradeep (UD) wells places significant requirements on the drillstring. Lengthy drillstrings lead to high tensile loads, which can lead to slip crushing of the drillstring; hoisting capacity issues; and drillpipe collapse capacity concerns at the blowout preventer (BOP). BOP shear rams may also have difficulty shearing today's high-strength, high-toughness drillpipe. Bottomhole assembly (BHA) connection failures pose greater risk and cost at UD well depths. This paper analyzes the many challenges associated with drill-string designs specifically for UD drilling (UDD). It presents emerging drillstring technologies that are solutions expected to increase depth capability for the industry's continued advancement of deep-drilling operations.

Loss of volatile acid species from upper firn layers at Vostok, Antarctica

Significant natural artifacts in ice chemical records have been pointed out in recent preliminary glaciochemical studies carried out in central Antarctic areas with very low snow accumulation rates (generally less than 5 g cm−2 yr−1). Several deep drilling operations are underway in these regions for long‐term paleoclimatic reconstructions. A detailed glaciochemical study has been carried out at Vostok Station in order to investigate post deposition changes of ion concentrations in the snow and firn layers. The results show that, in general, concentration profiles of species such as Cl, F, and NO3, partly deposited as gases, exhibit a rapid decrease in the first few meters, indicating that a fraction, sometimes major, of these compounds is expelled back in the atmosphere after deposition. Some redeposition process of the gases is likely in the upper firn layers. Surprisingly, a similar effect is found for methanesulfonate (MS), suggesting that this compound could have a gaseous component in central Antarctic regions. The data also show that Cl, F, NO3, and MSA may be slowly but significantly displaced in the firn layers by high sulfuric acid levels of volcanic origin. The drastic changes observed in the surface snow layers may severely question current interpretations of certain chemical data recovered in these areas and point out an urgent need for new field and laboratory experiments on the air‐to‐ice transfer processes prevailing under central Antarctic conditions.

Control system for axial deviation of holes in deep drilling.

Axial deviation of holes is a serious problem in deep drilling operations. This paper presents the development of a new drilling tool with a tool path control mechanism and in-process sensing system for hole deviation. Essentially, the cube corner prism is mounted on, the tool head for measuring of the machining position by laser. When the position of the tool head deviates from the setting axis, the guide- pad on the tool head slightly moves up and down in the radial direction with each tool revolution. As a result, the drilling point is shifted toward the radial direction. This method is verified to be effective for accurate deep drilling because the tool point moves along the setting axis of the laser.

Continental margin drilling program

The initial responses from OMB, Congress, and industry have been overwhelmingly positive in support of a proposed major drilling program along the U.S. offshore coastal areas in deep water.The extensive sedimentary deposits located along the U.S. continental slopes are, as yet, unexplored. There have been numerous suggestions that there is a significant potential for extensive reserves of hydrocarbons, but these suggestions are largely speculative. At the same time, there is a great amount of scientific interest in the geology of the continental margins, so it has been logical in recent months to propose a combined scientific and commercial study offshore. Such a proposal is being made to Congress by the National Science Foundation for the purpose of obtaining funds to convert the government‐owned Glomar Explorer (the ship that was originally built for the use of the C.I.A.) into a vessel capable of performing deep drilling operations and for other costs of running the program over the next 10 years. Industry is being approached to contribute 50% of the costs.

Upper Devonian Stratigraphy and Production Potential: Pennsylvanian: ABSTRACT

A new surge of drilling activity is under way in Pennsylvania, with significant development and exploration for oil and gas reserves in the Upper Devonian sandstones. Upper Devonian sedimentary rocks are present throughout 80 percent of the Commonwealth. Their origin can be traced to an eastern upland source area Appalachia that was elevated, possibly as a result of spasmatic collisions of the North American and North African continental plates during the Acadian orogeny. The clastic deposits spread from this eastern source area as a thick wedge of delta-plain redbeds of continental origin and merged westward into the Chemung marine facies. Oil and gas accumulated in the sand deposits of the Chemung facies which are distributed in a northeast-southwest trending belt in western Pennsylvania. Over 500 oil and gas fields lie within this petroliferous belt. Cumulative production has exceeded 1.2 billion bbl of oil and 8.5 Tcf of gas. Recent new-pool discoveries and successful pool-extension tests in eastern Indiana, Cambria, southern Westmoreland, and Butler Counties, plus untested Upper Devonian sands encountered during deep drilling operations in Westmoreland and Somerset Counties, will provide new areas for gas exploration and development in Pennsylvania. End_of_Article - Last_Page 1895------------

On the thickness of the magnetic crustal layer in South-Western Iceland

Various magnetic properties have been measured in 21 samples of drill chips, and 3 cores, recovered by deep drilling operations in South-Western Iceland. The drill holes pass through layers of basalt, basic hyaloclastites and tuffaceous sediments to a maximum depth of 2200 m. The magnetic properties are found to reside predominantly in magnetite, probably in deuterically oxidized primary titanomagnetite grains in the rock. The magnetite concentration in the samples studied has been estimated by magnetic methods; in a low-temperature area at Reykjavik this concentration and other magnetic properties of the drill chips resemble those in local oxidized surface basalt. At the high-temperature geothermal area at Reykjanes, drill chips are mostly low in magnetite between 400 and 1500 m depths, but samples from still deeper layers may be similar to those from Reykjavik. The lack of downward trend in magnetite content with increasing depth in the drill holes indicates that a layer of at least 2 km thickness may be responsible for observed magnetic anomalies in Iceland. This conclusion, supported by anomaly amplitude computations, is in contrast to recently published results on the magnetization of mid-ocean ridges. Apparent occurrences of relatively non-magnetic or reversely magnetic rock in the central volcanic zone of South-Western Iceland are discussed.

OUTLINE GEOLOGY OF THE SOUTHERN NORTH SEA BASIN

Summary The address outlines the geological results of exploration for natural gas in the southern North Sea Basin as derived from geophysical surveys and deep drilling operations. The greater part of the marine area is stratigraphically comparable with the landward continuation of the basin in northern Germany. Marine Tertiary is well developed; the Trias includes a representative of Muschelkalk and the Permian is bipartite, with a Zechstein including thick evaporites overlying the Rotliegendes. True folding is very gentle, deep-seated folds and faults trending predominantly north-west–south-east (in the west) and north–south (in the east). A major phase of movement occurred in pre-Aptian times, resulting in widespread transgression of late Cretaceous on to early Jurassic and Triassic rocks. The dominant tectonic feature is the widespread development of halokinetic structures due to movement of Zechstein salt, the forms varying from pillows to diapiric salt plugs. This movement began in the Triassic and continued through Jurassic, Mesozoic and Tertiary times.

Developments in Pennsylvania in 1959

Exploration in Pennsylvania during 1959 resulted in the discovery of 1 new gas field, 6 new gas pools, extended several gas-producing areas, and established a new producing-depth record in the state. A number of important dry exploratory tests were drilled during the year. The second offshore well in Pennsylvania, in Lake Erie on Block No. 2, was plugged and abandoned after finding salt water in the Gatesburg (Upper Cambrian) formation. The Block No. 2 lease has been surrendered. A second well will probably be drilled on Block No. 1 lease during 1960. In the Seven Springs field, Somerset County, a new-pool wildcat was successful when Pa. Tract 75 No. 3 by Peoples Natural Gas Company found gas in the Onondaga chert (Middle Devonian) at 8,472 ft. This is the deepest produci g-depth record in Pennsylvania. The well produced 10,933 MCF of gas without fracturing at a rock pressure of 3,400 psi in 10 days, and is the discovery well in the Kooser pool. Fayette County had the only new-field discovery in 1959. The Mueller-Herr well No. 1 by Manufacturers Light & Heat Company found gas in the Onondaga chert on the Laurel Hill anticline, resulting in the discovery of the Ohiopyle field. Deep exploration (Middle Devonian or older) found 1 new gas field and 5 new gas pools. Of the unsuccessful wildcats, 10 were new-field wildcats and 7 were new-pool wildcats. Two outposts were unsuccessful. There were 83 development gas wells completed and 14 dry holes. The greatest density of deep drilling operations was in the Clearfield County area where the production limits of three pools, which had formerly been considered to be separate, were merged into one long field, the Punxsutawney-Driftwood field, extending almost 50 miles northeast and southwest. 122 deep wells were completed in Pennsylvania in 1959, with a total footage of 850,025 ft. Of the 122 wells, 89 were gas wells and 33 were dry holes. A new shallow-sand (Upper Devonian or younger) gas pool was discovered when the Earl Young well No. 1 was drilled by James Drilling Company in Clearfield County. Production was from the Fifth sand. As in 1958 the secondary-recovery projects in the Bradford Field and the development drilling in the gas fields dominated the shallow-sand drilling activity during 1959. In all, 628 shallow-sand wells were completed. Of these, 215 were gas wells, 10 were oil wells, 54 were dry holes, and 7 were drilled for underground storage. 342 were drilled in connection with secondary-recovery oil operations. In addition to the 628 new wells, 29 shallow-sand wells were deepened. The total footage of the new and deepened wells was 1,452,759 ft. Oil production decreased from 6,471,680 bbls. in 1958 to 6,160,387 bbls. in 1959. Proved oil reserves were estimated at 113,858,000 bbls. on December 31, 1959. Gas production increased from 104,974,000 MCF in 1958 to 118,862,000 MCF in 1959. Gas reserves were estimated at 1,051,972,000 MCF at the end of the year. More than 68,000 bbls. of distillate were produced in 1959. Companies leased more than 2,000,000 acres for oil and gas exploration. The total footage drilled, both shallow and deep, was 2,302,784 ft.