bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Flow Simulation in Discrete Fracture Network Models
Authors: Basquet Rémy , Jeannin Laurent , Lange Arnaud , Bourbiaux Bernard , Sarda Sylvain 
Published: December 2007

Abstract
Advanced characterization methodologies are now able to provide realistic pictures of fracture networks. We recently developed a software to simulate the transient and pseudo-steady-state flows of a slightly compressible fluid in Discrete Fracture Network (DFN) models. This simulator is used to validate the fracture network geometry and to calibrate the hydraulic properties of the fractures via dynamic data obtained from flow meters, interference and well tests. This paper is dedicated to the extension of the methodology to gas cases, taking into account the high fluid compressibility and the non-Darcian effects near the well bore.
The main specific features of our simulator are described and illustrated through demonstrative examples. Our DFN simulation approach is based on an optimised explicit representation for both matrix and fracture media and a specific treatment for matrix-fracture and matrix-matrix exchanges. A pseudo-pressure function is included in the diffusivity equation to take into account highly compressible fluids. The hydrodynamic behaviour of gas fluid flow near the well bore is taken into account via a skin effect proportional to the flow-rate for both matrix-well and fracture-well transmissivities.
This innovative numerical simulator is validated against existing analytical solutions and compared with finite-volume solutions computed with a suitable grid. Then, for application purposes, a complex realistic case involving a multi-scale natural fracture network with small-scale fractures and major objects such as seismic and sub-seismic faults is presented. An interference test is simulated on a representative DFN model and on the equivalent dual-porosity model built thanks to up-scaling procedures. This up-scaled reservoir model is shown to remain consistent with the geological DFN model in terms of gas flow. This example illustrates the practical use of DFN models in our fractured reservoir modelling workflow.
A Shared-Memory Parallel Black-Oil Simulator with a Parallel ILU Linear Solver
Authors: Collins David A. , Grabenstetter James E. , Sammon Peter H. 
Published: December 2007

Abstract
A parallel adaptive-implicit black-oil reservoir simulator is described which is designed to run on shared-memory machines with the parallelism controlled by OpenMP calls. The basic design decisions leading to this choice are discussed. The changes which were required in the original non-parallel black-oil simulator to achieve parallel execution are discussed, as are the techniques for achieving good parallel speedups for simulator tasks such as building the Jacobian matrix.
The simulator uses a parallel implementation of a variable degree incomplete LU (ILU) factorization followed by a parallelized GMRES iteration to solve the linear system of equations associated with the Jacobian matrix. The techniques for achieving this parallelization are discussed, as are techniques for load-balancing some solver sub-tasks. The effect upon the ILU preconditioner of the reservoir decomposition needed to achieve the solver parallelization is discussed and techniques for reducing this effect by reordering within domains are examined.
The simulator has been tested on a variety of simulation problems and a number of 32-bit and 64-bit shared memory computers, with the number of processors used varying between 1 and 32. The speedups obtained are presented and analyzed, and the problems entailed in applying the simulator to very large problems (ten million to more than one hundred million active cells) are described. Results are presented for several simulation scenarios as run on several different computers.
Through Bore Drilling Systems: a New Drilling Option
Authors: Runia John , Murphy Eugene , Boyes John , Sutherland George , Sim David , Brown Paul 
Published: December 2007

Abstract
This paper describes a Through Bore Drilling and Logging System, which has been developed and tested over the past four years with increasing levels of success.
The key components of the system, as it stands today, are: A PDC bit with a removable and re-insertable 2 ½" ID center insert and latching mechanism.A string of memory logging tools (gamma, resistivity, density, neutron and sonic measurements) with 2 ¼" OD.A 3D rotary steering device, with 2 ½" full through bore.A removable and re-insertable MWD probe type tool, which leaves a 2 ½" full through bore after retrieval.
The trials and jobs carried out to date are also briefly described, together with the currently perceived strengths and weaknesses of the current system.
Quality in HSE Management Systems
Authors: Prewitt Annette 
Published: December 2007

Abstract
This paper describes Quality's role in HSE systems and provides detail information on one offshore drilling contractor's HSE system through the company's quality system, Global Excellence Management System (GEMS). Quality tools used in HSE systemElements/main areas of the management system and integration with HSEComparison of international standards and regulatory requirements for HSE & Quality. MMS SEMPIMO ISM CodeISO 9001:2000ISO 14001API Spec Q1Malcolm Baldridge National Quality Award Program: 2002 CriteriaWorkforce involvement and implementation to meet system objectivesUse of Best Practices in development of a global system for MODUs.Importance of a Balanced Scorecard
Presented in this paper is an evaluation template for assessing a company's system compliance and key results in several performance measures for HSE.
Ultimate Capacity of a Disposal Well in Drilling Waste Injection Operations
Authors: Abou-Sayed Ahmed S. , Guo Quanxin , Meng Fanhong , Zaki Karim 
Published: December 2007

Abstract
Drilling waste disposal through downhole hydraulic fracturing is often the preferred waste management option because it can achieve green operation and often has favorable economics. Most field situation comprise of injection in either dedicated well or in the annulus of an existing well. Containment of the disposed waste must be ensured and one of the questions in drilling waste injection operations is what the capacity of a disposal well or annular scheme is? The answer to this question depends on downhole waste storage mechanisms. It is evident from laboratory simulation studies and field operation experience that multiple fractures are created in drill cuttings injection (DCI) operations and the capacity of a disposal well is much larger than that estimated from single fracture simulations. More importantly, as more solids are injected into the disposal formation, the local stress is modified. Because of this change in local stress, fracture shapes and extents at the beginning of a DCI operation can be significantly different from the fracture shapes and extents at the end the operation. Modeling of this fracturing evolution process is necessary and essential to ensure the safe containment of the disposed waste and to estimate accurately the disposal capacity of a drilling waste disposal well.
This paper presents a numerical algorithm for modeling the multiple fracturing and fracture evolution process during drill cuttings injection operations. Case studies show that the modeling results based on multiple fracturing have significant impacts on DCI operations engineering such as injection pressure requirement and disposal capacity. The results also provide insight into best practices for the containment of disposed waste, when injection can continue into a previous zone and when is there a need to inject into a different zone or when a new disposal well should be drilled. For the purpose of brevity, "disposal well" will be used to designate either a dedicated injector well or an annular injection scheme.
Challenges of Drilling an Ultra-Deep Well in Deepwater – Spa Prospect
Authors: Rohleder Stephen A. , Sanders W. Wayne , Williamson Roger N. , Faul Gary L. , Dooley Lynn B. 
Published: December 2007

Abstract
Conoco drilled the Spa Prospect, Walker Ridge 285 #1, in the Gulf of Mexico to a depth of 29,452' MD / 29,434' TVD. The Spa Prospect was a subsalt well encountering approximately 9,981' of salt. The Transocean Deepwater Pathfinder, a dynamically positioned drillship, was utilized to drill this well in 6,654' of water. Original planned total depth for the well was 31,600' MD / 31,000' TVD. This represented one of the deepest wells ever planned in the Gulf of Mexico. All geologic objectives were reached by 29,452' and drilling operations were terminated.
This paper describes the challenges involved with planning the well, documents the execution, and concludes with lessons learned. The well planning included the following: Location selection criteria for avoiding shallow hazards while meeting geological objections,Pre-drill pore pressure and fracture gradient estimation,Hydraulics design and its relationship to drill string selection,Casing and wellhead program objectives,Landing string design,Lost circulation assessment,Mitigation of annular pressure in trapped annuli, andThe implementation of test rams to reduce BOP testing times.
The execution section of the paper describes experiences encountered and the technologies utilized.
Magnolia Casing Design for Compaction
Authors: Ibekwe I. A. , Coker O. D. , Fuh G. F. , Actis S. C. 
Published: December 2007

Abstract
ConocoPhillips' Magnolia project will utilize a Tension Leg Platform (TLP) in a record water depth of 4674 feet (1425 m) in Garden Banks block 783 in the Gulf of Mexico. The wells will be predrilled and then completed with a platform rig. Production is expected from unconsolidated, fine grained and over-pressured Pleistocene and Pliocene formations. Reservoir compaction was identified as a drive mechanism for the field. Rock mechanics studies indicated that reservoir depletion in the low-strength and high-porosity reservoir rocks could result in significant reservoir compaction due to initial shear failure followed by pore collapse. This paper will describe our analysis of such rock failure mechanisms and projected strains, which served as the basis for deriving estimates for reservoir compaction and stretch of overlying strata.
The team faced a unique challenge to develop a casing design that would address reservoir compaction concerns. By itself, casing design was only one part to a solution that involved developing a comprehensive well construction and completion strategy that could deal with the reservoir compaction problems. The cost of casing failure would have significant negative impact on project economics.
A concerted effort was undertaken to study the geology and the rock characteristics of the formations in this field. The resulting casing design strategy conforms with, and in some aspects improves upon, ConocoPhillips' current casing design philosophy. This paper discusses two of the major design factors: 1) the effect of tension on the casing in the overburden above the reservoir and 2) the effect of compression on casing in the reservoir. Specific design criteria were developed for each of these factors. The field was sub-divided into different reservoir compartments, then the maximum stretch and compressive strain that is expected in each compartment was calculated for the reservoir and overburden zones.
The selected design strategy was applied to the casing design with a view to optimizing wellbore life and project economics of each well. The result is a unified approach to compaction that begins in geomechanical analysis and ends with the financial decision process.
Subsea Abandonment From Semi With Surface BOP
Authors: Norwood Edwin B. , Chinoyerem Njoku , Ranyis Victor 
Published: December 2007

Abstract
Sub-Sea Abandonment With Surface BOP. Baram 8 (BA-8) consists of a single well in 179 feet of water supported by a wellhead protection jacket in the Baram Field. The well was drilled in 1968 and the jacket was installed later in the same year, both of which collapsed in 1975, pulling both the conductor and the riser with it. The collapsed structure resulted in distortion of conductor and casing strings at the seabed. The well was in normal production mode, producing less than 0.2 MMscf/d of gas at the time of collapse. The subsea safety valve closed, thus preventing hydrocarbon release after the collapse. In September/October, 2001, the conductor and casing strings were cut to a depth of 18 feet below seabed, leaving the remaining casing shape non-circular. Deeper excavation was not possible at that time due to limitations of the jack-up in use.In July 2002, the Atwood Falcon, a semi-submersible drilling rig, was equipped to excavate some 30 feet below seabed using the latest in seabed excavation equipment. The Jet Prop tool uses a large propeller to push a high volume column of water vertically downwards onto the work area. This brings the seabed material into suspension and disperses it from the work area.The Jet Prop was able to create a large excavation around the wellhead with stable side slopes for safe diver operations. The soil from the excavation area was dispersed laterally across the seabed by operating the Jet Prop while manoeuvring the rig on its moorings. To support the cutting of conductor and casings some 30 feet below the seabed, a full saturation (SAT) dive system was installed on the riser deck. This allowed continuous diving without weather shut down.
After cutting the conductor and casing, a 30-inch conductor was installed to the surface. A used Permanent Guide Base was modified and installed on the rig's spider beams to serve as a "false rotary". Space out of 30-inch conductor connection was designed to allow a 10-foot "stroke". The rig's spider beams provided lateral support.
A 13 5/8 × 5000 psi ram/annular surface BOP (SBOP) was prepared in Singapore. The SBOP, placed on top of the 30" conductor, was located in the rig's cellar deck. Circulation returns were completed through a jack up-style bell nipple.
The existing semi-submersible BOP control pod and choke & kill (C/K) lines were used on the SBOP for easy installation and control.
In order to have effective operation, all the various components were pre-fabricated while the rig was drilling. The SAT dive system was installed and commissioned prior to arrival at BA-8. The pipeline burial equipment, Jet Prop, was air freighted to Singapore and assembled in the cellar deck. This equipment was powered with the rig's mud pumps. The SBOP was assembled into a special frame to use the rig's subsea Koomey pod in a surface-mounted upper female for SBOP control. Existing C/K lines were connected to the SBOP using No. 5 Cameron Hubs.
After the initial set-up, the P & A procedure followed a normal program.
Performance Gains with 5th Generation Rigs
Authors: Keener Chip , Keji-Ajayi Ibukun , Allan Rod 
Published: December 2007

Abstract
Transocean's fleet of newbuild, deepwater, 5th generation rigs have accumulated an aggregate 35 rig years work experience. Among the exceptional accomplishments: deepest water depth (2,966 m / 9,727 ft – Unocal Discoverer Spirit)deepest subsea completion (2,198 m / 7,209 ft – Unocal Discoverer Spirit)deepest moored operation (2,442 m / 8,009 ft – Shell Deepwater Nautilus)simultaneous well test / crude storage / offload – (BP Discoverer Enterprise)
The rigs are showing significant performance gains, some of this attributable to dual or off-line activity, and some in benefit of higher specification equipment (pump pressures, flow rates, etc). Many among the operator community are now factoring generous premiums for these efficiencies in their bid evaluations. In confirming and assessing the gains, Transocean have undertaken a modeling exercise, comparing the performance of 5th generation rigs with earlier builds. Representative performances have been distilled from the IADC Reports, such that well curves can be predicted and compared for each of the rig classes.
Dropped BOP Stacks: Understanding Causes to Improve Prevention
Authors: Sattler Jeffry P. 
Published: December 2007

Abstract
Although thankfully not a common occurrence, when a BOP stack is dropped, it is most often a catastrophe. With the understanding of the causes of dropped stacks provided in this paper, one will be able to identify specific steps to minimize the likelihood of this type of failure on future projects in any floating drilling operation.
Aphron-based Drilling Fluid: Novel Technology for Drilling Depleted Formations in the North Sea
Authors: White Craig C. , Chesters Adrian P. , Ivan Catalin D. , Maikranz Sven , Nouris Rob 
Published: December 2007

Abstract
Drilling depleted reservoirs is fraught with a host of technical and economic problems that often make it unprofitable to further develop some mature fields. Most of the problems center around uncontrollable losses and differential sticking. Frequently, less expensive drilling fluids will be used in a particular interval, even though it may have the propensity to damage the formation. The reasoning holds that such fluids will offset the high costs of losing more expensive muds to the formation. If operators turn to underbalanced drilling as an alternative, the extra time and equipment required for a safe operation can seriously degrade project economics in some applications.
A specialized invasion-control drilling fluid has been developed to drill reservoirs prone to lost circulation. This fluid combines certain surfactants and polymers to create a system of micro-bubbles or aphrons that are encapsulated in a uniquely viscosified system.
Aphron based systems are engineered drilling fluids that aid in well construction by controlling losses in depleted, high-permeability sands while stabilizing pressured shales or other formations. One of the more attractive features of an aphron-based system is that it does not require any of the extra equipment used in air or foam drilling. There are no compressors, high-pressure hoses or connections to add costs and safety concerns. The system uses conventional fluid-mixing equipment to form tough, flexible micro-bubbles.
This paper describes the development and application of the specialized micro-bubbles-based drilling fluid for controlling downhole mud loss in a depleted reservoir in the North Sea. The key issues of this project were excessive overbalance drilling conditions (&gt; 5,000 psi) leading to the risk of highly expensive lost circulation and open perforations in the upper producer, requiring temporary sealing during drilling. The well was successfully drilled to TD without any drilling fluid losses. The authors will detail the laboratory methods used to generate appropriate formulations, the operational procedures, and field application.
Transient Gel Breaking Model for Critical Wells Applications with Field Data Verification
Authors: Bjørkevoll Knut S. , Rommetveit Rolv , Aas Bjarne , Gjeraldstveit Helga , Merlo Antonino 
Published: December 2007

Abstract
The paper addresses the problem of predicting pressure peaks when starting pumps after a static period while drilling a well. It demonstrates that laboratory measurements with standard Fann viscometers and a gel breaking model can be used for predicting such peaks.
Fluids with properties that are similar to those of real drilling fluids have been studied in detail in the laboratory. Gel breaking and thixotropic behaviour were first analysed in detail through rheometer measurements. The fluids showed a pronounced time dependent behaviour. Afterwards each fluid was placed in a flow loop where circulation was started after a static period. The time dependent signals were logged and analysed. An initial sharp pressure peak followed by a slow decrease in pressure was typical.
A local model based on rheometer measurements that predicts gel breaking pressures versus time is presented. The authors are not aware of any other such model.
The local model has been integrated in a transient drilling simulator which predicts the pressure peaks that follow when starting pumps after a static period. Gel strength is broken successively from the pump, down the drill string, and up the annulus. The model will help drilling engineers to determine whether extra care is required when starting pumps
Controlled field measurements have been made in two North Sea HPHT wells, one with water based and one with oil based drilling fluid. Gel breaking pressures were measured when starting pumps after static periods of different lengths. The effect of rotating the drill string prior to pumping was tested.
The transient model reproduced measured data with reasonable values of gel model parameters.
The observed effects are expected to be of importance when drilling any critical well, which may be deep water, HPHT, or extended reach wells.
Imaging Unstable Wellbores While Drilling
Authors: Edwards Stephen , Matsutsuyu Bruce , Willson Steve 
Published: December 2007

Abstract
This paper presents a case study of borehole instability from 4 wellbores on the Gulf of Mexico (GOM) shelf, offshore Louisiana. Logging while drilling (LWD) borehole images are combined with observations of cavings and modeling of borehole shear failure in order to diagnose the mechanisms of instability and thus select the appropriate remedial action.
It is observed that instability due to shear failure of intact rock (borehole breakout) can be suppressed by increasing mud weight. However, where pre-existing planes of weakness such as bedding planes and fractures dominate the mechanism of instability, mud weight increases do not necessarily lead to a more stable hole and can in fact further destabilize the wellbore.
Poroelastic Effects on Borehole Ballooning in Naturally Fractured Formations
Authors: Helstrup Ole A. , Rahman Khalil , Chen Zhixi , Rahman Skeik. S. 
Published: December 2007

Abstract
This paper presents a study on wellbore ballooning and (in)stability in naturally fractured formations. A model containing a single fracture is analysed using a poroelastic numerical approach for a number of in-situ stress ratios and rock matrix permeabilities. It was found from this study that the stress response for this system depends not only on the in-situ stress, but also on rock matrix permeability and time. The results are compared with that from an analytical linear elastic solution approach, and it is shown that the results are significantly different.