bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Type of Hydraulic Hammer Compatible with Conventional Drilling Fluids
Authors: Plácido João Carlos R. , Lage Antonio Carlos V. M. , Carvalho Daltro J. L. , Hardie Ronnie , Wajid Rasheed 
Published: December 2007

Abstract
This paper describes the tests and concept behind a new hydraulic hammer. The objectives of these tests were to evaluate penetration rate performance of this hammer when used in conventional drilling conditions.
To date the usage of hydraulic hammers has been hindered due to limited compatibility with drilling fluids solids content. Therefore, this hammer was conceived to operate with all kinds of drilling fluid, including Lost Circulation Materials. Additionally, this hammer would be used with conventional tri-cone bits. This is significant because inter-bedded formations can be drilled without repeated changes to the bottom-hole assembly and drilling can continue in the event of hammer failure.
The technology consists of a rotating valve system that alternately directs fluid to a piston that drives down a steel mass to strike the rear of the bit and then to a port that bypasses the piston. This action allows the mass to return to its original position ready for the next downward stroke. The valve operates at a known frequency that is directly proportional to flow rate.
Due to these unique characteristics, the Hard Rock Drilling JIP decided to test the hammer, the results of which are discussed here.
Mobile Offshore Jackup Units: A New Innovation for the Next Frontier in the Gulf of Mexico - Deep Drilling for Natural Gas on the Shelf
Authors: Robertson John E. 
Published: December 2007

Abstract
With the resurgence of deep gas drilling in the Gulf of Mexico specifically on the shelf, the focus has shifted to the need for a new design in offshore drilling units. This paper will discuss the reasons for pursuing exploration in such an environment, why it is more cost effective to build new rigs instead of modifying existing units, and the design and equipment used to enhance its performance.
Novel Wireline Coring System
Authors: Fleckenstein W. W. , Eustes A. W. 
Published: December 2007

Abstract
The value of core samples to enhance reservoir evaluation and completion strategies has long been recognized. A large percentage of the cost of coring is the rigtime associated with the tripping of the corebarrels. As rig rates increase, particularly in deepwater areas, the cost of coring becomes prohibitive due to excessive trip costs. A solution to this problem is to trip the core from the well at wireline log recovery speeds, yet still recover the length and diameter of core associated with conventional coring operations.
Since the 1960's, international teams which include the United States, Europe, Japan, and Russia, have developed a wireline coring system for recovering 4 to 5-1/4" (101 to 133 mm) diameter, ice and rock cores to 12,000 feet (3,660 m) in Antarctica and Greenland. This paper describes this wireline coring technology. This includes the self-contained fluid circulation, cuttings recovery, instrumentation, core barrel, core catcher, and core bit systems. The operational history for the recovery of both ice and rock cores on multiple wellbores, including the Greenland Ice Sheet Project, is presented and possible oilfield applications, emerging from a recent optimization study, including replicate coring, are discussed.
Application of Stream Conversion Methods to Generate Compositional Streams From the Results of a Multi-Million Cell Black Oil Simulation Study of the Shaybah Field
Authors: Al-Awami Bassam , Hemanthkumar K. , Al-Awami Fatema , MohammedAli Mansour 
Published: December 2007

Abstract
Detailed compositional simulation of a giant reservoir with many components is not practical. However, detailed multi-million cell black oil simulation of giant reservoirs is now quite feasible. In this work we apply an efficient method to generate the compositional rates from a black oil simulation of the giant Shaybah field.
In situations where the reservoir recovery mechanism is not dominated by compositional effects, an Equation of State (EOS) based stream conversion method can be used. This stream conversion method relies on the fact that when laboratory PVT data measured on available well stream compositions are used to generate the black oil PVT tables, some of the compositional information is lost. The stream conversion model retains this valuable compositional information and applies it to each producing well completion in the black oil simulation at every time step.
As proof of concept, the stream conversion method was applied to a black oil simulation and to a limited (eight-component) compositional simulation to generate a 17-component compositional stream and the results were compared to the respective full EOS compositional simulation for a relatively small sector (250,000 cells) of the giant Shaybah field. The compositional stream rates are in excellent agreement with the stream converted black oil results. As would be expected, the computational costs of using the EOS based compositional simulator (with 17 components) is in excess of 40 times the black oil simulation time for the small sector model. In general, the stream conversion method can be used to generate the dynamically varying compositional streams from any black oil simulation for use in the design and operation of surface facilities and in calculating the amounts of a certain cut (e.g. NGL) from the production streams.
WAG Optimization for Gas Floods above the MME
Authors: Johns Russell T. , Bermudez Leonardo , Parakh Harshad 
Published: December 2007

AbstractWater-alternating-gas floods (WAG) are commonly used to improve sweep efficiency in heterogeneous reservoirs. There has been little reported in the literature, however, on the effectiveness of WAG processes where the gas is enriched above the minimum miscibility enrichment composition (MME). This paper examines how to optimize WAG processes for enriched gas floods above the MME, particularly as a primary recovery method. Compositional simulations of x-z cross-sections are used to quantify the effects of WAG parameters, numerical dispersion, level of enrichment, and heterogeneity on local displacement efficiency and sweep efficiency.The main conclusions of this research show that the richer the gas above the MME, the fewer the number of WAG cycles required for maximum oil recovery at a given WAG ratio. Another significant observation is that over-enrichment above the MME improves recovery the most when the largest permeability layers are at the bottom of the reservoir. Continuous slug injection performs better than WAG when the largest permeability layers are at the bottom of the aquifer, richer gases are used, and the vertical to horizontal permeability ratio is small.
Reservoir Monitoring and Continuous Model Updating Using Ensemble Kalman Filter
Authors: Nævdal Geir , Johnsen Liv Merethe , Aanonsen Sigurd Ivar , Vefring Erlend H. 
Published: December 2007

Abstract
The use of ensemble Kalman filter techniques for continuous updating of reservoir model is demonstrated. The ensemble Kalman filter technique is introduced, and thereafter applied on two 2-D reservoir models. One is a synthetic model with two producers and one injector. The other model is a simplified 2-D field model, which is generated by using a horizontal layer from a North Sea field model.
By assimilating measured production data, the reservoir model is continuously updated. The updated models give improved forecasts. Both dynamic variables, as pressure and saturations, and static variables as the permeability are updated in the reservoir model.
Formation Damage Assessment and Remedial Economics from Integration of NMR and Resistivity Log data
Authors: Altunbay M. , Sy R. , Martain R. 
Published: December 2007

Abstract
The main objective of this study is to devise a methodology, utilizing a wealth of information gained from NMR (Nuclear Magnetic Resonance) and resistivity logs, and to assess and to quantify formation damage due to filtrate invasion in the flushed zone. Quantification of the damage, in terms of damage-ratio within vertical resolution of the logging tools, provides the input for the calculation of economic implications of the problem. This, in turn, helps us decide either the need or the scope of the remedial action.
The quantification of the damage relies on the determination of the amount of shift in the relative permeability curves for the flushed zone against the undamaged zone. Depth of investigation for the NMR logs is limited to the flushed zone while the resistivity logs provide a deeper insight into the formation. The DWT (Dual Wait Time) mode of an NMR logging pass yields the movable and immovable parts of the porosity in addition to the type of the fluids contained within. Derivation of an absolute permeability profile from the Bound Water Model in conjunction with synthetic capillary pressure-based RBVI (bulk volume irreducible as capillary pressure approaches to infinity) or Purcell's technique along with water saturation profile from DWT NMR data yield the foundation for computing the relative permeability characteristics of the formation by using empirical equations. A water saturation profile for the uninvaded zone is computed from resistivity logs using the proper petrophysical model while corresponding relative permeability characteristics are obtained via the same set of equations. The superimposed relative permeability curves from NMR and resistivity-based data indicate the presence and/or amount of the shift of the curves between the flushed-zone versus the uninvaded zone. The amount of increase in effective permeability to water and drop in effective permeability to hydrocarbons are computed from the superimposed relative permeability curves. The radius of the damaged zone is determined from the 2D inversion of resistivity data and inserted into the DR (damage-ratio) equation together with the effective permeability of the undamaged and damaged zones. Skin factors can also be computed as a function of the available data. The annual revenue loss per well, formation damage dollars lost (FD$L)3, due to filtrate invasion-based damage can then be assessed by multiplying the damage-ratio with the current price of the hydrocarbon and the rate of production. To further evaluate the economics, the damage-ratio and FD$L can be plotted for various damaged radii to determine the threshold radius for economically justifying the cost of remedial action.
Calibration of Log Permeability Models Using Fluid Flow Measurements
Authors: Poe B. D. , Butsch R. J. 
Published: December 2007

Abstract
This paper presents the results of a research effort to develop, test, and apply a numerical minimization procedure for determining the coefficients and exponents of some of the more popular formation permeability estimation models that are used with open hole well log analyses. The calibration of the log permeability models is performed using reference values of formation effective or absolute permeability (or conductivity) derived from fluid flow measurements. Sources of the reference formation permeability values that have been used in this study include reservoir pressure-transient test analyses, commingled multilayer reservoir production performance analyses using production log information, core analyses, and formation tester results.
In this paper, an efficient numerical minimization algorithm has been implemented to determine the best estimates of the coefficients and exponents of the Coates1 and Timur2 log permeability models that agree with fluid flow measured values of formation permeability (or conductivity). These models were chosen due to their popularity, but the basic minimization procedure presented in this paper is applicable to other log permeability prediction models as well.
Special consideration is given to the implementation of the Coates1 model in the minimization process by the introduction of the Heaviside unit step function into the published model for use in the minimization process to relate the bulk volume water irreducible and the total porosity (or irreducible water saturation and effective porosity).
The Use of An Integrated Approach in Estimation of Water Saturation and Free Water Level in Tight Gas Reservoirs: Case Studies
Authors: Ding Sheng , Pham Tai , Yang AnPing 
Published: December 2007

Abstract
To reduce the uncertainty in the estimation of hydrocarbon in place and fluid contact in tight gas reservoirs, it is essential to integrate core data and log analysis. A newly developed saturation-height function approach has been successfully applied to calibrate log analysis to better define petrophysical properties such as formation water saturation and free water level in tight gas reservoirs. The application of this approach has played a critical role in exploration and development decision-making processes for tight gas reservoirs.
Unlike most of the models published in the literature, this approach accommodates different forms of J-Sw regressions, which is applicable to different pore geometries and very powerful in tight gas reservoirs. Also, water saturation is calculated continuously from log porosity and free water level without formation resistivity and Archie exponents. In addition, this approach estimates free water level by iterating on water saturations until matching those derived from log data.
In a case of a tight gas "wild-cat" well where the porosity from most of the well logs is much larger than that from core analysis, this new approach reconciled the difference and predicted the rock quality up-dip. The results are confirmed by the pressure transient analysis from the production test. Based on the integrated analysis, the decision to abandon the current well and the up-dip drilling location saved the company millions of dollars.
In the second case, the reservoir simulation failed to get a history match for a tight gas field. The parameters of this new approach were calibrated to several key wells with core data.
The results of the calibration were then used to populate water saturation throughout the field. Eventually, the history match was achieved and an infill drilling opportunity was identified for this field.
In summary, this paper proposes an integrated EXCEL-based saturation-height approach. Case studies in tight gas reservoirs using the new approach demonstrated that failures were avoided, and opportunities were realized.
Assessment of Remediation Treatments in Underground Gas Storage Wells
Authors: Brown Kenneth G. , Frantz Joseph H. , Sawyer Walter K. , Heckman Glenn C. 
Published: December 2007

Abstract
The underground gas storage (UGS) industry uses more than 400 reservoirs and 15,000 wells to store and withdraw natural gas and is thus a significant contributor to gas supply in the United States.1 Previous work indicates that many gas storage wells show a loss of deliverability each year due to numerous damage mechanisms and it is estimated that tens of millions of dollars are spent each year to recover or replace this lost deliverability.2
Prior Gas Technology Institute (GTI) studies3,4 have been aimed at qualitatively reviewing completion and deliverability enhancement techniques used in the storage industry, identifying specific damage mechanisms present in storage reservoirs, and establishing procedures for damage mechanism identification. This paper presents key results of a major new study sponsored by the Gas Technology Institute (GTI) that focused on a comprehensive, quantitative assessment of the effectiveness and longevity of the various stimulation treatments employed in the UGS industry.
Specifically, this paper summarizes the major results of the most comprehensive quantitative study conducted to date of stimulation treatments employed in the UGS industry. The study involved seven operators and 23 reservoirs (14 carbonate and 5 sandstone). Data were collected, entered into the database, and reviewed for 381 stimulations in 365 wells. Deliverability data were entered for 159 stimulations in 155 wells (67 in carbonate reservoirs and 88 in sandstone reservoirs) with sufficient data for inclusion in the study.
The most popular stimulation treatments currently employed in the UGS industry are identified, the effectiveness and longevity of various treatment types are quantified and compared, and a new quantitative indicator designed to capture the results of effectiveness and longevity calculations in a single benchmark indicator is presented. In addition, the frequency and duration of cleanup effects for various treatment types and the post-stimulation decline rates typically observed for various treatments are also quantified and compared.
The implications of conclusions reached in the study, as they relate to future UGS R&D efforts, are also discussed, and specific areas of additional study are recommended.
Evaluation of a Hybrid Water-Frac Stimulation Technology in the Bossier Tight Gas Sand Play
Authors: Rushing J. A. , Sullivan R. B. 
Published: December 2007

AbstractThis paper presents results from an evaluation of water-frac stimulation treatments in the Bossier tight gas sand play in the East Texas Basin. The primary objective of our study was to compare the stimulation effectiveness of conventional water-fracs with a hybrid water-frac technology. The hybrid water-fracs combine the advantages and benefits of both conventional gel and water-frac treatments. Stimulation effectiveness, measured in terms of fracture half-length and conductivity, was evaluated using short-term pressure buildup testing integrated with decline type curve analysis of long-term gas production data. The results of our study indicate that we can achieve longer effective fracture half-lengths and higher effective fracture conductivities more consistently using the hybrid water-frac technique.
Production and Injection Profiling: A Novel Application of Permanent Downhole Pressure Gauges
Authors: Ouyang Liang-Biao , Sawiris Ramzy 
Published: December 2007

Abstract
Production and injection profiling through permanent downhole pressure gauge, a novel and unique application, has been proposed in the present paper. Theoretical development of the new technique is first provided. Example studies are then given to illustrate the application of the technique. Application scenarios, practical issues as well as key impacting parameters have also been addressed. Finally, a field case study implementing the new technique for a long horizontal well has been performed to demonstrate how the production profiles calculated from PDG data compare to the results from a recent PLT survey which turns out to be expensive yet unsatisfactory.
The technique could be applied to real-time production and injection profiling for different well configurations (vertical, horizontal, deviated and multilateral) and bring tremendous financial benefits through replacing conventional production logging surveys that could be cost-extensive for horizontal or multilateral wells offshore.
A Comprehensive Model of Horizontal Well Completion Performance
Authors: Furui K. , Zhu D. , Hill A. D. 
Published: December 2007

Abstract
Horizontal wells or laterals are completed as openhole, slotted liner, cased and perforated, or gravel pack completions. We have developed a comprehensive skin factor model to predict the performance of any of these completion types, and calibrated this model with extensive finite element simulations of flow for a horizontal well completion. This model can be used to predict the performance of virtually any horizontal well completion.
The new completion skin factor model accounts for the effects of formation damage, convergent flow to perforations and slots, and flow through slots, with interaction among these effects. To account for formation damage, we extended our previous rigorous model of a damaged horizontal well to include the presence of perforations within, or extending through, the damage zone. The formation damage model is also integrated with the models of slotted liner performance to model these completions. The model of slotted or perforated liner performance is based on the relationship between pressure drop and flow rate for turbulent flow in these geometries. The slotted liner model accounts for partial plugging of the slots by grains of formation minerals or precipitates (scale). Turbulence effects are a major part of the apparent skin factor for these completion types.
The model shows the recommended conditions to obtain high productivity (low skin factor) completions in horizontal wells. In particular, the interactions among damage effects and skin effects due to perforations or slots are shown to greatly affect horizontal well completion performance. The models developed can be applied to design optimal completions for horizontal wells or laterals.
Geostatistical History Matching Using a Regional Probability Perturbation Method
Authors: Hoffman B. Todd , Caers Jef 
Published: December 2007

Abstract
Petroleum reservoirs are large, geologically complex and usually contain multiple wells. Building numerical models for reservoirs is not a simple task, and it is further complicated when production data is incorporated into the reservoir models. Integrating production data into the model requires an iterative process of changing the model and observing how those changes effect the flow of fluids in the model. This process should be as efficient as possible because each iteration requires a time-consuming flow simulation, and it should honor all available data so that the predictive models are as accurate as possible.
This paper lays out a general procedure for modifying geostatistical realizations in a geologically consistent manner that efficiently matches production data. To achieve this goal various regions in the reservoir are perturbed by different amounts, yet no geological artifacts are created at the borders of these regions. The methodology relies on a region-wise perturbation of the probability model used to generate the geostatistical realization. Perturbing probabilities rather than actual petrophysical properties guarantees that border artifacts are avoided. A new, simple yet efficient optimization method is developed that can jointly optimize the magnitude of the perturbations and is able to handle a large number of regions. We demonstrate with realistic synthetic examples that the method allows perturbing under various geological scenarios, and a 3D realistic synthetic case of a North Sea fluvial channel type reservoir demonstrates how the method would work in practice.