bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cementing Practices for Tubingless Completions
Authors: Clark Charles R. , Jenkins Robert C. 
Published: December 2007

This paper was prepared for the 48th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
This paper describes field cementing practices for tubingless completions. practices for tubingless completions. Application of new cementing techniques has resulted in a significant increase in success frequency. Some of the techniques adopted were based on articles recently published in the literature while others published in the literature while others were developed through field experimentation. A before/after comparison of success frequency is made along with a detailed description of the changes in field practices. All of the wells analyzed have been drilled in the South Texas area.

Introduction
During 1970, 1971, and the first quarter of 1972, relatively poor cementing success was experienced in 2-7/8" tubingless wells drilled in the South Texas area. Table 1 reflects the primary cementing success ratios for this primary cementing success ratios for this period. Typically, these wells were drilled period. Typically, these wells were drilled to total depth of 7100' with a 10.5 ppg water base mud and were considered to be routine. However, a review of the expenditures for remedial squeezing to repair primary cementing (average crest per well of $1500) and the resultant deferred or lost production indicated a problem of major magnitude.
In light of the poor success ratios, it was decided to exert a maximum effort on primary cementing for tubingless wells to see if success frequency could be improved. Two company primary cementing studies were essentially completed in the first quarter of 1972. The recommendations concluded from these two studies plus field equipment and operational changes have lead to improved cementing success for tubingless completions. Table 2 reflects the cementing success for 12 months history since implementing the new procedures. Only one triple tubingless has been completed (a cementing success) since the change in procedures. Therefore, a before/after comparison has not been made for triple tubingless completions. This paper will give a brief description of the techniques used during 1970, 1971 and the first quarter of 1972, and a detailed discussion of the cementing procedures currently being used.
Comparison of Friction Factor Correlations for Gas-Liquid Flow in Horizontal Pipes
Authors: Hernandez Florencio , Brill James P. 
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
All published correlations for predicting flowing pressure losses account for irreversible energy losses due to wall shear stress through a Fanning or Moody type friction term. Evaluation of this term requires that one be able to predict the value of a friction factor. Use of predict the value of a friction factor. Use of the well known Moody diagram, or one of many empirical equations that describe specific parts of the Moody diagram, is the accepted way to determine friction factors for single-phase flow.
Most investigators have taken advantage of previous knowledge in single-phase fluid flow previous knowledge in single-phase fluid flow to predict flowing pressure losses when gas and liquid flow simultaneously in pipes. Thus, mechanical energy balance equations, which form the basis for single-phase flow equations, have been modified for two-phase flow through simple analogies. These analogies have resulted in wall stress terms that include any irreversible energy losses between phases and all of which are again expressed in terms of a Moody type friction term. Thus the problem becomes, in part, one of determining a two-phase or mixture part, one of determining a two-phase or mixture friction factor.
Correlations for predicting two-phase friction factors for horizontal pipe flow have been published by many authors. All published correlations are based on experimental data, and no previous attempts have been made to compare these correlations.
Published equations for predicting two-phase flowing pressure loss may be solved explicitly for a two-phase friction factor. However, the resulting equations are a function of liquid holdup. Thus, a valid comparison of friction factor correlations would rely on using data for which measured holdup data as opposed to predicted values were available. The only reliable liquid holdup data available for pipe sizes 1 in. and greater were published by Eaton, Andrews and Beggs.
The gas-water data of Eaton and Andrews for 2- and 4-in. pipe (266 tests) and the air-water data of Beggs for 1- and 1 1/2-in. pipe (58 tests) were used for this study. Using these measured holdup values, friction factors (called measured values) were calculated from the appropriate pressure loss or mechanical energy equations for pressure loss or mechanical energy equations for the correlations of Eaton et al., Beggs and Brill, Dukler (Case II), and Gushov et al.
These correlations were chosen since they are the ones that are used most frequently for predicting two-phase flowing pressure losses in predicting two-phase flowing pressure losses in horizontal pipes.
The Combustion Interchangeability Of Natural And Substitute Gases
Authors: Larson Dennis H. 
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers Office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
Over the past 40 years, several investigators have developed methods of calculating for combustion interchangeability of gases for appliance-type burners. However, when these methods are used to calculate interchangeability for more current types of gases such as substitute natural gases (SNG) or revaporize LNG, there is considerable disagreement. Currently, additional research work is being conducted to resolve these differences. Results to date show that the American Gas Association method or indexes are most suited to today's gases on U. S., appliances. In addition, we have fund that today's burner designs allow more flexibility in interchanging gases. Compositions of SNG, for example, which may not burn satisfactorily in a cast iron drilled-port burner, popular 40 years ago, will burn properly in the newer popular 40 years ago, will burn properly in the newer stamped-metal burner. Consequently, further work is being done to extend the A.G.A. indexes to reflect this added stability of newer burners.

Introduction
The U.S. gas industry is embarking on major programs to import liquified natural gas (LNG) and programs to import liquified natural gas (LNG) and to produce substitute natural gas (SNG) from solid and liquid feeds. The compositions of these gases are expected to vary considerably from the natural gas now being used in the U.S. It is, therefore, important to determine the combustion interchangeability of these new gases with conventional appliances now equipped for natural gas.
In the late 1940's and 1950's, several groups studied the problem of interchangeability as applied to natural gas. From data collected by the A.G.A. Laboratories, indexes were developed by A.G.A. and by Weaver of the National Bureau of Standards. Additional work including theoretical foundations was done by Grumer, Harris, and Rowe, at the U.S. Bureau of Mines. Another significant set of data and indexes were developed by Delbourg and Schneck in France.
Dynamic and Static Measurements on mm-size Shale Samples
Authors: Nes O.-M. , Sonstebo E.F. , Horsrud P. , Holt R.M. 
Published: December 2007

Abstract
A system for acoustic velocity and static Young's modulus measurements on small (mm-size) shale samples is presented. The equipment has been tested on both soft and hard shales, including cuttings. Even though more experimental testing, must be carried out to confirm and improve its performance, it is demonstrated that reliable measurements can actually be performed on the small samples. Moreover, the results appear consistent with results attained from larger plugs using more conventional test methods. This technology represents a relatively fast and inexpensive method of attaining dynamic and static data from sub-surface formations. Use of cuttings and small samples can greatly improve the data availability, particularly where proper cores are not available.
P. 23
Implementation of Cuttings Reinjection at the Ekofisk Field
Authors: Nagel N.B. , Strachan K.J. 
Published: December 2007

Abstract
In response to increasing concerns over the environmental effects of the disposal of drill cuttings to the sea, a number of North Sea operators have begun to dispose of cuttings through injection into underground strata. Phillips Petroleum, as part of the Eko II redevelopment program for the Ekofisk field, conducted an evaluation of cuttings disposal options prior to selecting cuttings reinjection for all cuttings disposal from the new 2/4X wellhead platform.
In support of the selection of the final alternative for reinjection of cuttings, reinjection of slurrified cuttings via a dedicated well into the mid-overburden overlying the northeastern flank of the reservoir, an extensive engineering study was performed. Within the study, a number of issues were evaluated and reviewed: the relevant experiences of other North Sea operators; the economic evalution of various mud systems and disposal alternatives; a complete review of the geologic structure of the overburden for determining the optimal location of reinjection; numerical simulations of fracture behavior and performance; well design considerations; final selection of the well location; contingency planning; and a subsidence risk assessment. The subsidence risk assessment, performed in cooperation with an outside consultant, evaluated the unique concerns of reinjection into the overburden overlying a compacting reservoir.
Cuttings reinjection was initiated late in 1996 and by early 1998 more than 700,000 barrels of slurry had been reinjected into a single completion interval. Difficulties with the well have been relative minor, though the well has plugged-up several times, and the reinjection operation is considered successful. Building upon these results, plans are now being implemented for cuttings reinjection via dedicated wells at the Eldfisk field, another compacting reservoir lying to the southeast of Ekofisk.
P. 95
An Experimental Analysis of Anelastic Strain Recovery of Synthetic Sandstone Subjected to Polyaxial Stress
Authors: Yassir N. , Wang D.-F. , Enever J.R. , Davies P.J. 
Published: December 2007

Abstract
This paper describes, for the first time, a unique investigation of ASR using synthetic sandstone samples formed under applied polyaxial stresses. The strain relaxation in all tests invariably gave a good indication of the principal stress orientations. Measured strain relaxation ratios were approximately equal to corresponding applied stress ratios up 1.5, suggesting that, with a knowledge of one of the principal stresses, in regions of low stress anisotropy, stress can be calculated directly from strain. At stress ratios of 2 and above, corresponding relaxation strain ratios were variable, time- dependent and generally higher than the stress ratios. This suggests that shear stresses associated with stress anisotropy result in material damage that is partly responsible for the measured relaxation strain.
Correction of strains for "Poisson" effects reduced data scatter at the higher stress anisotropies but gave a poor correlation between applied stress and a) strain magnitudes, b) calculated stress, for a measured Poisson ratio (v) of 0.3. Lower v values gave better data fit, but it is suggested that the use of a Poisson correction of (he measured strain. Using low values of v, is unrealistic. The strain relaxation mode was assessed using the Kelvin-Voight model. The strain relaxation curves are not perfectly linear in normalised strain/time space. The material behaviour cannot therefore be fully reproduced using this visco-elastic model. Anisotropic samples especially seem to deviate from a linear trend, again suggesting that stress anisotropy and related fabric damage have an effect on the ASR response.
P. 161
An Innovative Energy Approach to Analyze Wellbore Stability
Authors: Santos Helio , Roegiers Jean-Claude 
Published: December 2007

Abstract
Wellbore stability has been traditionally analyzed by comparing the stresses to the formation strength. In addition, most of the problems have occurred in the shales; hence, have been attributed to the chemical interaction between the drilling fluid and the rock. However, field evidences urge for (he development of an improved way to analyze the stability of oil wells, due to the increase in challenges resulting from considering more difficult reservoirs.
This paper presents an innovative way to analyze wellbore stability using energy concepts. The rock mechanics aspects are emphasized; laboratory experiments usually interpreted via a mechanistic way should actually be evaluated in a more comprehensive way with energy. By analyzing the failure process of rocks, wellbore instability is explained by (he creation of surface fractures, with subsequent mud penetration. The paper describes the most energetic phenomena during (he drilling of a well, with the corresponded effects on the stability.
P. 255
Shear Strength and Stiffness of Clay-Rich Sediments during Drilling Operations
Authors: Fam M.A. , Dusseault M.B. 
Published: December 2007

Abstract
During exposure to different fluids and temperature gradients, the shear strength and the stiffness of shales may change because of changes in their chemical and physical properties. Time-dependent borehole stability models should incorporate these changes in order to capture actual field conditions. In this study, analytical treatments are employed to predict changes in shear strength and stiffness of soft shales caused by concentration diffusion processes (hat may arise during drilling operations. Analysis is based on the double-layer theory and the modified effective stress concept. Artificial shale specimens with different smectite contents are prepared using a slurry-consolidation technique. Fluid exchange (higher tonic concentration) is imposed on the specimen before undrained triaxial and unconfined compression tests. Volumetric strains and pore pressures are recorded with time during pressure diffusion, concentration diffusion and shearing stages. Apparently, changes in the shear strength and stiffness depend on the initial condition of the system. Soft homogeneous sediments experience an increase in the strength and stiffness with the increase in pore fluid concentration. On the other hand, stiff cemented systems and clay mixtures may show the opposite trend due to the breakage of bonds and the generation of excess pore pressure.
P. 283
Effects Of Induced Pore Pressure On Stability Of Wellbores Drilled In Shales
Authors: Chen X. , Tan C. P. , Haberfield C. M. 
Published: December 2007

Abstract
Due to the low permeability of shales, excess pore pressures will be induced in the material in response to the volume change of the rock matrix during drilling. These excess pore pressures will reduce the effective confining pressure applied on the material which will lead to a less stable wellbore condition. However, the extent to which the induced pore pressure influences wellbore stability varies dramatically with the in-situ stress regime, wellbore trajectory, and the poroelastic and strength anisotropies of the shale.
This paper examines wellbore stability under different drainage conditions taking into account variations in the in-situ stress environment, wellbore trajectory and shale properties. Design charts derived from the analyses are then presented and their application discussed. Finally, the effects of induced pore pressure on wellbore stability are demonstrated through numerical modelling of borehole deformation of a thick-walled hollow cylinder shale sample under different drainage conditions. Comparison of numerical results with laboratory measurements shows good agreement.
The investigation provides further insight and understanding of the effects of induced pore pressure on stability of wellbores drilled in shales. The design charts enable assessment of the effects of in-situ stress regime, wellbore trajectory and poroelastic properties of the formation on wellbore stability to be readily made. In addition, recommendations for appropriate drainage conditions for use in wellbore stability analyses enable more accurate prediction of the safe mud weight window.
Borehole Stability in Shales: A Physico-Chemical Perspective
Authors: Fam M.A. , Dusseault M.B. 
Published: December 2007

Abstract
Stability problems encountered in shale formations significantly increase the cost of drilling operations. It is not possible to identify a single main factor in shale instability; failure mechanisms are only now beginning to be identified, and the dominant processes seem to vary for different conditions of stress, mineralogy, fabric, and geochemistry. This article reviews a number of physical and chemical concepts in borehole stability analysis and raises several issues related to the activity coefficient and cation exchange processes. It is shown that the degree of saturation and clay particle separation have significant impact on the activity coefficient of tested cores. A simple coupling model based on the modified effective stress principle shows that when a shale with low porosity and high specific surface (reactive shale) is subjected to an increase in pore fluid salt concentration, a pore pressure front may develop. This front may trigger changes in effective stress and shear strength around the borehole. This may be a major destabilizing mechanism in the more reactive shales (generally the smectitic shales).
P. 461
Is Capillary Suction a Viable Cohesive Mechanism in Chalk?
Authors: Lord Charles J. , Johlman Carolyn L. , Rhett Douglas W. 
Published: December 2007

Abstract
This paper is based on a series of residual water analyses performed on Ekofisk Field chalk samples. The main objective of this work was to critically evaluate the importance of capillary suction as a cohesive mechanism in chalk. .
Capillary suction models have been proposed in the literature to explain the structural weakening that occurs when water is injected into chalk reservoir rocks. These models theorize that mineral grains are held together by the surface tension of water menisci. Water saturations of 5 - 10 % are generally considered optimum for this mechanism. As additional water is injected into the rock, the menisci disappear and the rock loses cohesive strength. Proponents of these models claim that the superior strength of "dry" chalk is also due to capillary water which is so tightly bound that it survives normal laboratory drying procedures. Despite the popularity of this theory, no evidence has been published that verifies the presence of capillary menisci in dried samples.
We used a thermal desorption - mass spectrometry technique to quantify the amount of adsorbed water that remains fn dried reservoir rock samples. The results of these analyses on Ekofisk Field chalks demonstrate that the capillary suction cohesion model is not a valid mechanistic description of chalk behavior. Our data show that the residual water content of chalk is at least twenty times too low to support capillary water menisci. An alternative weakening mechanism, such as mineral dissolution at grain-to-grain contact points, needs to be considered. This type of critical testing is necessary in order to develop a realistic and accurate model of waterflood response in chalk reservoirs.
Induced Seismicity Analysis for Structure Identification and Stress Field Determination
Authors: Gaucher E. , Cornet F.H. , Bernard P. 
Published: December 2007

Abstract
In 1993, during the development of the European hot-dry-rock geothermal field at Soultz-sous-Forets (France), 44,000 m3 of water were injected to stimulate the natural fracture system of this granitic rock mass. Some 16,000 microseismic events were recorded by a network consisting of a hydrophone and three four-component seismic sensors cemented in the granite at the bottom of observation wells. Multiplets (close earthquakes with similar waveforms) are retrieved in order to find local structures and correlate them with major fractures observed in the well by acoustic imaging and flow logs. Among the eleven identified and relocated multiplets, eight of them deline a planar structure, which is presumed to be a fracture plane. Two of the multiplets lie on a linear structure and one of them is the intersection of two previous planar multiplets. This leads to a description of the fracture network within a few tens of meters around the borehole. In addition, in order to compare the geometrical rupture parameters of the "multiplet" fractures with those of the "borehole" fractures, focal mechanisms of multiplets are modeled by using a statistical approach. This is done by combining the geometry of the fracture planes, the P wave polarity and the S wave polarization, as seen only at the four stations. The S waves polarization shows an hexagonal anisotropy with a North- South horizontal symmetry axis, which is consistent with the regional maximum horizontal stress direction.
P. 545
Geomechanical Characterization of the Overburden Above the Compacting Chalk Reservoir at Valhall
Authors: Kristiansen Tron Golder 
Published: December 2007

Abstract
A study was initiated to improve the geomechanical input to the full field compaction/subsidence prediction model for Valhall and wellbore stability analysis models used to plan long extended reach wells in the Valhall field. The results are also applicable for other geomechanical activities in the field, like well design, waste injection, hydraulic fracturing stimulation in the reservoir and the design of a potential waterflood. The study used an integrated approach to characterize the Tertiary formations above the chalk reservoirs. In-situ stresses (magnitude and direction), pore pressure and geomechanical deformation properties of the formations were determined. Results, observations and conclusions are presented.
P. 193
Experience Transfer to Development Projects: How and Who?
Authors: Buset H. , Pagenhart A. , Throndsen T. I. 
Published: December 2007

Abstract
Various techniques have been used to facilitate transfer of experience and technology to different projects from operations and related projects. Results from different models are discussed, along with continuing challenges. Today's advances within global communication can significantly improve information sharing in design management and technical solutions. Many different professionals within the operations and project organizations are involved in experience transfer, and methods for organizing their interactions to streamline progress are discussed.