bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Mechanism in Drillstring Vibration
Authors: Lin Yao Qun , Wang Yu Hwa 
Published: October 2008

ABSTRACT
In deep well drilling for oil and gas, it has been observed and recorded that severe vibrations build up and die down periodically. The beating phenomenon is a frequent occurrence, particularly, during all startup tests and on most of those exhibiting the low frequency torsional vibration. This paper interpreters the field data of beating like phenomenon and reveals a new mechanism, namely stick-slip vibration, which may initiate three-lobe pattern at the hole bottom. The possible self-excited vibration without sticking is also explored in this paper.

INTRODUCTION
The external excitation on the drill bit is usually regarded as the sole cause of the vibration of the drillstrinq. Paslay and Bogy considered the vibration due to the intermittent contact of the bit and the hole bottom in 1963 [1]. Huang and Dareing discussed the buckling and lateral vibration induced by the drill fluid in 1968 [2]. Bogdanoff and Goldberg presented a random model to explain the breakage of drill pipe in 1961 [3]. However severe vibration was usually attributed to the bit's running over the three-lobe bottom pattern at a constant speed, although the cause of the formation of the three-lobe bottom pattern was not understood [4,5,6]. Based on this attribution, Dareing and Live say successfully explained the longitudinal and torsional vibrations with triple rotary frequency in 1968 [5]. Dareing further indicated the possibility of eliminating the three-lobe bottom pattern by controlling the rotary speed in 1983 [7]. He also explored the self-excited vibration initiated by a small vertical harmonic motion of the bit [8]. Eronini et al investigated the interaction between the bit and rock and presented a dynamic vibration model in 1982 [9]. In analyzing field data, Dawson, Lin and Spanos postulated in 1987 that the drillstring vibration was a stick slip motion [10J; this was followed in a study by Kyllinstad and Halsey in 1987 [11]. By examining the beating phenomenon in oil well drilling, Lin and Wang demonstrated that the vibratory phenomenon of beating was a stick-slip motion. The effects of viscous damping, rotary speed and natural frequency of the drillstring on stick-slip vibration were also discussed [12].
This paper re-iteratesthat beating in drilling is induced by the nonlinearity of the total resistance to the drillstring (dry friction, viscous damping and torque on bit). This is done by further examining Denison's data and theory [13]. The formation of three-lobe pattern at the hal e bottom and self-excited vibration without the bit being stuck are also explored.

Summary OF PREVIOUS WORK
Our previous work was first concentrated on the large amplitude torsional vibration of the drillstring with bit off the bottom. The drill string was modeled as a one-degree-of-freedom torsional pendulum which has the following equation of motion
(MATHEMATICAL EQUATION IS AVAILABLE IN FULL PAPER)
New Approach for Installing Welded Conductors on Platforms Without Interrupting Adjacent Drilling and Production Operations
Authors: Lace N. , Fahrmeier C.F. 
Published: October 2008

Abstract
This paper describes the equipment and procedures used to install welded conductors on Shell U.K. Exploration and Production's Tern Platform located in 550 feet of water in the North Sea. The equipment and procedures which were used allowed conductors to be installed without interrupting drilling and producing operations. This method of installing conductors is more economical than conventional methods and allows conductors to be installed at a schedule dictated by the progress and success of the drilling program.

Introduction
The placement of conductors into offshore platforms can be divided into three separate operations defined as follows: 'Installation' refers to placement of the conductor down to a penetration in the sea-bed achieved by the conductor's own weight. 'Drive' refers to achieving further penetration by means of an impact or vibratory hammer. 'Drill/drive' refers to achieving further penetration by using a combination of drilling a lead hole and driving with an impact or vibratory hammer. This paper focuses on the equipment and procedures used in the 'installation' of conductors in the Tern platform, that is, to a penetration achieved by the conductor's own weight.
The placement of conductors in offshore platforms is typically accomplished with a crane barge during the installation of the platform, with the drilling rig as part of the drilling program, or with a combination of the two approaches. The choice as to which method to use is influenced by several factors:Cost of crane barge or drill rig spread vs. speed of installation. While crane barges typically have a higher day rate than drilling rigs, they can install several conductor strings simultaneously and can handle longer section lengths than a drilling rig.If the drilling and completion program is more successful than planned, several unused, but paid for, conductors which were installed by the crane barge will be left stockpiled in the platform.By making conductor installation part of the drilling program, the conductors can be installed in an "as-needed" basis, thus, there is no stockpiling of conductors in the platform.The increased speed of conductor installation by crane barges allows wells to be brought on-line sooner.
Conductors for the Tern platform were installed by using a conductor jacking spread provided by Marine Contractor Services, Inc. in conjunction with Varco-BJ Ltd. and adapted for use on the Tern platform by the operators Shell Expro, the Shell/Esso U.K. North Sea joint venture.
On the platform, the conductor jack was set up adjacent to the drilling rig as shown in Figs. 4 and 5. Because this equipment can operate independently of the rig, conductors were installed while drilling operations were ongoing.
A Practical 3-D Seafloor and Sub-Bottom Mapping System
Authors: Matthias P.K. , Newton F.L. 
Published: October 2008

ABSTRACT
A new technique of applying three-dimensional rendering to an integrated product of side scan sonar, bathymetry and sub-bottom data has been developed. The computer generated products are displayed in stereo 3-D. The virtual product supports geologic interpretation, ROV operations and ocean engineering.

INTRODUCTION
The ocean sciences have been dramatically impacted over recent years by improvements in computer technology. High speed dedicated processors allow modelers to process comparatively large databases in a short amount of time. Large capacity data storage with fast access speeds support model interaction and revision. One major current challenge is to provide a user interface which supports interpretation through visualization.
Visualization allows modelers to view and manipulate data in spatial rather than numerical format and infer patterns and relationships based on the brain's interpretation.
This study culminated in the application of high speed computers and visualization software to display virtual products of side scan sonar imagery, bathymetry and sub-bottom data.
Side scan sonar's have been used to provide sonographs of the ocean floor since the early 1960's. This remote sensing device is subject to many radiometric and geometric distortions common to satellite remote sensing. Many of the same techniques are used for preprocessing to correct these distortions.
Manufacturers of side scan sonar have made gains toward correcting the radiometric distortions. The bulk of the geometric corrections and image extraction tools require coupling the sonar with a powerful top-side processor. Post-processing techniques used on the USGS MIPS system and Triton Technology's QMIPSTM have been described in the literature 1,2. Fig. 1 is a "typical" analog hardcopy of a sonograph over aircraft wreckage while Fig. 2 depicts a sonograph generated by Q-MIPS. Fig. 2 is an image of a PB4Y-2 aircraft imaged by International Deep Sea Survey with Triton Technology's Q-MIPS and the AMS-120 side scan sonar in Lake Washington, Seattle.
The lower third of Fig. 2 is a copy of the Q-MIPS display of port and starboard channels. After drawing a rubber rectangle around the aircraft, Q-MIPS zooms the boxed region to fullscreen. A color lookup table (LUT) and associated histogram are displayed across the top.
The Q-MIPS sonar image processing system digitizes the analog signal at up to 750 kHz. Slant range correction and water column removal are performed in real time. The data is stored on high density 1.25 GByte write Once Read Many (WORM) optical disks while it is displayed on the screen. Q-MIPS data format includes the storage of 1024 8-bit or 16-bit pixels per channel per sonar "ping".
Driven Model Piles Tested in Calcareous Sand in a Large Calibration Chamber
Authors: Parkin A.K. , Yee Y.W. , Tan C.P. , Willoughby D.R. 
Published: October 2008

ABSTRACT
Model pile tests have been conducted in samples of calcareous sand, derived from both on and off shore sources in Australia. Samples 1.2 m diameter by 1.8 m high were formed and saturated in a large calibration chamber, modified to allow three piles to be driven into each sample. The silty fines created unique problems in sample formation and in creating a realistic test environment. Results of initial pull testing are discussed and compared with the CPT test.

INTRODUCTION
Carbonate soils found in Bass Strait, a major hydrocarbon producing region off the southeast coast of Australia, generally provide relatively poor support for driven piles [1]. Drilled and grouted piles [2] which provide extremely high skin frictions, upwards of 400 kPa, are now the preferred solution, but are datively expensive. In an effort to improve the cost effectiveness of grouted pile foundations, Esso Australia Ltd. conducted an extensive experimental program in 1987 and 1988 which included tests of 100 mm and 150 mm driven piles and grouted piles in a modified laboratory calibration chamber at Monash University, Melbourne. The tests were performed in three incremented carbonate soils that ranged in grain size from a medium sand to a sandy silt.
This paper presents descriptions of test equipment, procedures, and results of driven pile and cone electrometer tests performed in two of these soils, designated A and C. These were medium and silky sands, respectively. Results obtained in the sandy silt are reported in a companion paper[3]. Soil A was recovered References and illustrations at end of pare by dredging from a site in Bass Strait, while Soil C was derived from an on-shorn Tertiary deposit in South Australia. In respect of their compressibility and fines content, these soils differ notably from the clean silica sands normally used in calibration chamber studies, introducing severe problems in handling and sample formation, as well as causing notable differences in pile behavior.

THE CALIBRATION CHAMBER AND ACCESSORIES
The Monash University calibration chamber was developed from the design of a small chamber described by Holden [4], and was constructed solely for the purpose of calibrating friction cone electrometers in sand.
It consists essentially of a large triaxial sample of sand, 1.2 m diameter and 1.8 m high, enclosed in rubber membranes and compressed by a lateral water jacket and a base piston (Fig. 1). The exterior cell wall is of cavity consummation to permit the imposition of Ko lateral constraint, and the base piston acts through a water cushion for the measurement of vertical stress. An overhead reaction frame provides restraint to hold the cell together, and also mounts the driving equipment for a standard cone electrometer on the sample axis. Further details are given by Chapman [5], Bellotti et al. [6] and others.
Development of a Backup Control System With a Serial Hydraulic Data Transmission System and a Subsea Multisensor System
Authors: Okamoto K. , Nakagawa O. , Himuro H. , Tsugaki S. , Ihara M. 
Published: October 2008

ABSTRACT
A highly reliable control system for sub sea equipment had been jointly developed by Kawasaki Heavy Industries, Ltd. (KHI) and Japan National Oil Corporation (JNOC) from 1985 for 4 years. This system has a multiplexed electro-hydraulic system as a main control system and a serial hydraulic data transmission system as a backup control system.
This Prim presents the following two subsystems and a device as part of the developed total control system shown in Fig. 1.Serial hydraulic data transmission systemSub sea multi-sensor systemUnderwater power generating unit

INTRODUCTION
As a backup control sys tern, a direct hydraulic System and a sequential hydraulic System are very popular in the sub sea control system for an offshore oil production. However the reliabi1ity of data transmitting capabilities is very poor compared with a main control system such as a multiplexed electro-hydraulic system. To improve the capabi1ities a serial hydraulic data References and i 1lustrations at end of paper. transmission system had been developed, which is an application of pressure propagation in pipe lines with pulse code modulation.
A sub sea multi-sensor system had been developed by applying LAN(Lcml Area Network) technique and power 1ine carrier's technique. I t consists of analogue sensors, digital sensors, one loop data way (parallel two-core cable), inductive connectors and control unit,
An underwater power generating unit had been developed to supply electric power to control pods when main electric power fed from a surface platform failed. This unit is driven by hydraulic w fed by hydraulic pumps located on the surface platform,
The design conditions for this control follows, which are comparable to those offshore oi1 fields.Environmental conditionWater depth : 300mWater temperature : +0--35°CVibration : 2-13.2Hz ± 1m13.2--8OHZ 0,7GProduct ion conditionPressure :max.350kgf/cm2Temperature:0-100°CHydraulic fluidMaximum pressure : 210kgf/cfiWorking fluid : seawater based fluid or seawaterTemperature s ()-29°CElectric power in control podAC source : AC100V ± 15%, 60Hzf ± 10% 3 phase or single phaseDC source : DC 24V+20%-10%

SERIAL HYDRAULIC DATA TRANSMISSION SYSTEM
This hydraulic data transmission system was confirmed to lx applicable to a floating type production system by empirical tests with scale models.RequirementData transmitting between quite a distance is possible as several thousand inters via a hydraulic 1ine.Additional equipment and components are minimized in comparison with a sequential hydraulic SystemA Hydraulic power unit designed exclusively for operation of gate valves and choke valves can be uti1ized for generation of pressure waves without any modifications.
Takula Oil Field and the Greater Takula Area, Cabinda, Angola
Authors: Dale C.T. , Lopes J.R. , Abilio S. 
Published: October 2008

Summary
The Greater Takula Area comprises four offshore fields, Takula, Wamba, Numbi, and Vuko that produce oil predominantly from Upper Cretaceous reservoirs. The fields are located approximately 40 kms west northwest of the Malongo terminal, in Cabinda, Angola in water depths of 50-75 m (150-220') (Figure 1). Current production levels are approximately 177,000 bpd of 34° API oil.
The first oil well in the area was drilled in 1971 on a seismically defined horst structure beneath a pervasive salt section that is associated with the opening of the South Atlantic. It flowed 5600 bopd from carbonates of Lower Cretaceous age. It was not until late in 1979, however, that a far more significant hydrocarbon accumulation was found in the Cenomanian sands of the Vermelha Formation. All four fields produce primarily from Vermelha sands deposited on a trend of structures whose genesis was controlled by listric normal faulting and salt movement. The total area of closure for these fields at the Vermelha level is approximately28,000 acres (114 sq km) with a maximum oil column of 440'.
To optimize the oil recovery from these fields a staged development project has been ongoing since 1980. It involves initial primary solution gas and/or gas cap expansion drive production, followed by a water flood pressure maintenance program for the major reservoirs. This project has been guided by a detailed reservoir analysis using 3-D seismic, core studies, wire line log analysis, reservoir mapping and simulation matched to production history. To date these fields have produced 300 MMSTB.

Exploration History
The Cabinda Gulf Oil Company started exploration activities in the then Portuguese administered province of Cabinda in 1954. On November 22, 1957 the original concession covering both onshore and offshore acreage was awarded. By the early seventies the concession had been renegotiated to the current 10,116 sq km with the relinquishment of the onshore and additional acreage offshore out to the 200 m isobaths. The present concess ion is divided into three areas - A, B, and C. All the current production comes from Area A fields. (Figure 1).
The first well was drilled offshore in 1966. The discoveries of the Malongo fields followed soon after. These successes focused exploration on the offshore. By today, 14 fields have been discovered and put into product ion, the 1argest of these fields being Takula.

Regional Setting
Angola lies midway along the length of the South Atlantic rift. The rift developed in late Mesozoic time as plate tectonic activity caused the separation of South America from Africa. The tectonic elements and sedimentary sequences observed along the margins resulted from the evolution of the rift. (e.g., Lehner P. and DeRuiter, P. A. C., 1977). A series of basins developed along the rift. The Cabinda concession is located in the Congo basin which is flanked to the north and south by the Gabon and Cuanza basins, respectively.
The Veslefrikk Transfer Systems
Authors: Bjelland O. 
Published: October 2008

ABSTRACT
This paper is a description of the Veslefrikk transfer systems which are the connections between the permanently installed fixed wellhead platform and the floating production platform on the Veslefrikk field. The main elements in the system are a 40 m long telescopic bridge and a number of 150 m long free hanging flexible pipes and electrical cables transferring fluids, power and control signals. The transfer systems operational and design requirements are addressed as well as a general description of the system design and analysis.

INTRODUCTION
The Veslefrikk field development consists of a jacket wellhead platform (VFA) and a semisubmersible production and quarters platform (VFB). VFB is moored close to VFA and the normal operational distance between the two platforms is 36 m. The water depth at the Veslefrikk location is 174 m.
The major system split between the two platforms and location of main equipment are as follows:
VFB:Process facilitiesPower generationLiving quartersWater injection SystemGas export compressor systemCrude export pumping systemGas lift compressor systemMud pits and cleaning systemMud pumpsCement pumps VFA:Wellhead systems for production and water injection wellsmanifold systemDrilling derrickConnections for gas and crude export pipelinesPig launchersSale-shakers for primary mud-cleaning
Due to this system separation, a transfer system as shown in fig. 1 and fig. 2 is required between VFA and VFB compromising the following main elements:telescopic bridgeflexible pipe systemelectrical cable system The main function of the telescopic bridge 1S to connect VFA and VFB together for transfer of personnel working on VFA and support the connection lines for the utility systems on VFA supplied from VFB.
The flexible pipe system consists of pipes for transfer of production fluid from the wellhead and manifold system on VFA to the process facilities on VFB. Further, the system consists of pipes transferring produced oil and gas from VFB to VFA where the export pipelines for oil and gas are terminated. Gas lift and water injection are transferred from VFB to VFA through the system.
The mixing and pumping systems for mud and cement are located on VFB. Flexible pipes transfer mud and cement over to VFA and return mud back to VFB
The power generation plant and the main control centre are located on VFB. The electrical cable system transfers electrical power from VFB to VFA and control signals between the two platforms.

OPERATIONAL PHILOSOPHY AND REQUIREMENTS
Transfer system considerations Previous examples of floating platforms operating alongside fixed platforms were evaluated in the early Veslefrikk project study phase in 1986 to establish the feasibility of such a concept. The fixed/floater combination had been used on the Odin field in 1983 where a semisubmersible drilling rig provided drilling mud, casing, storage and extra accommodation facilities. Also a number of flotels had been in operation anchored close to a fixed platform to provide extra accommodation.
The Delta Tower: A Light, Compliant Tower for the Gulf of Mexico
Authors: des Deserts L. , Cortez A.J. 
Published: October 2008

ABSTRACT
The concept which is described in the paper is applicable to fields located in the Gulf of Mexico in water depths ranging from 1 000 to 1 750 feet. The concept is a compliant tower which permits the use of conventional equipment for drilling and production and which is immediately applicable without any need for specific developments. Because of the low quantities of materials involved, and since conventional equipment can be used, the concept is particularly well adapted for marginal fields, as well as for larger ones. Material quantities are given for different water depths and deck loads, as well as dynamic behavior and the outline of the installation procedure.

INTRODUCTION
The Delta Tower is a concept which was originally developed through a joint industry study supported by 10 American oil companies, for hydrocarbon production in 2 500 feet of water depth. See reference 1. It is a comp1iant tower supported on a fixed base and having its stability brought by some axial tubes located at its periphery. The connection between the tower and the base is ach leveled by some tubu1ar members allowing the heeling of the tower and able to transfer the overall shear force to the foundation. The paper will present the latest works performed on this concept, which are related to water depth ranging between 1 000 and 1 750 feet.

MAIN PRINCIPLE
The Delta Tower is a concept which features a compliant structure, called lithe Tower", set on top of a fixed one, called lithe Base". The compliancy of the upper part is brought by three different means : the axial tubes, the buoyancy tank and the shear device.
The axial tubes, located at the periphery of the tower, are rigidly connected to the tower and to the base at their top and bottom extremities respectively. In addition, they are simply guided along the tower and the base to prevent any possib1e buck1ing. These tubes act as vertical springs and, because of their eccentricity with regards to the axis of the tower, they provide the necessary righting moment in the tower when it heels under wave action. They also permit the transfer of all vertical loading between the tower and the base.
The buoyancy tank, located below the water line at a low enough level to minimize the wave loads, produces also a part of the righting moment and permits to reduce the apparent weight of the structure which is supported by the axial tubes.
The shear device, located at the bottom of the tower permits the transfer of all shear forces and torsion moment between the tower and the base. This shear device may be composed of a set of shear pins - shear guides or by a set of shear members. The high flexibility of these shear members combined to their axial resistance creates d pseudo-articulation between the tower and the base.