bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Temperature on Drilling Mud Resistivities
Authors: Lynn Ralph D. 
Published: December 2007

Abstract
A cell is described for measuring drilling mud resistivities at temperatures up to 350°F. Rm, Rmf and Rmc were measured at temperatures from 75 to 225°F with 100 psi pressure maintained on the mud system. Hence, Rmc is measured on the undisturbed mud cake under differential pressure. Fifteen synthetic mud samples and 25 field samples were measured. Some of the more important results areThe effect of elevated temperature on Rmf and Rmc is not the same as for NaCl solutions having corresponding resistivities at 75°F.The resistivity ratios, Rmf/Rm and Rmc/ Rm, vary with temperature in a different manner for different muds.Resistivity ratios may be widely different for different muds.Rmc may be different for undisturbed mud cake under differential pressure than when it is disturbed for measurement.Some chemical additives greatly affect the resistivity values as well as resistivity ratios.Mud resistivities may vary widely while drilling.

Introduction
Quantitative interpretation of electric logs requires reliable values for the mud resistivity, Rm, the mud filtrate resistivity, Rmf, and the mud cake resistivity, Rmc, under borehole conditions. For example, the resistivity of the formation water, Rw, is often calculated from the self-potential curve by the equation:
In this equation, K has a value which is relatively constant for certain conditions of lithology and borehole temperature within a specified area. Thus, in the use of this equation to find Rw, it is evident that an error in the determination of Rmf will result in an error of like magnitude in the calculation of Rw.
Rm is sometimes measured in the borehole with the collapsed microsonde but it is more difficult to make routine measurements of Rmf and Rmc under borehole conditions. When these resistivities are determined by sample measurements at the surface the correction to borehole conditions is of major importance. Temperature, pressure and differential pressure are some physical fact is that may affect resistivity values but temperature is by far the most important. Loan found no measureable effect of pressure on Rm up to 1,000 psi, but he found that Rmf and Rmc are affected by differential pressure. For differential pressures of 100 psi and 1,000 psi, Rmf was as much as 20 per cent greater for the higher pressure but Rmc was as much as 10 per cent smaller for the higher pressure.
The Phenomenon of Free Fall During Primary Cementing
Authors: Beirute R. M. 
Published: December 2007

ABSTRACT
For many years the oil industry has been performing primary cementing jobs perhaps without a complete understanding of the actual flow behavior of the fluids in the well during the cementing operation. It is well known that in many jobs the well "goes on a vacuum", "U tubes" or "free-falls" while the heavy fluids (cement slurries, spacers) are being pumped down the casing. When this occurs, one loses control of the job rates since the column of fluids in the casing free-falls at rates different than the pump rates at the surface. During the first stages of free-fall, the free-falling column of fluids accelerates and the free-fall rate is larger than the surface pump rate. This early acceleration causes a "partially empty" or "discontinuous" zone or gap to form between the free-falling column of fluids and the wellhead. It is possible that this initial acceleration is not detrimental to the cement-mud displacement process, unless the job was designed to be pumped under plug flow and the accelerated rates take it out of the plug flow regime. On the other hand, toward the end of free-fall, the free-falling column of fluids decelerates and the free-fall rate can fall below a minimum desired pump rate for turbulent flow displacement. This again can be detrimental to the job success. It is obvious, therefore, that a better understanding of the phenomenon of free-fall and the design of ways to handle it are a must if the industry is going to fully control the mud displacement process.
To gain this additional understanding, a mathematical model simulating the phenomenon of free-fall that often occurs during primary cementing has been developed. The model has been programmed as an integral part of a cementing computer simulator. This paper discusses the free-fall model and reviews information obtained using the simulator that explains and helps in the understanding of the hitherto obscure phenomenon of free-fall. Using the model, it is now possible to obtain a prediction of the expected rate of returns during free-fall, as well as the surface and bottomhole pressures during the job.
Predictions made with the simulator have been checked versus several field cases. The simulator results compare extremely well with the field measurements. Some of these comparisons are included in this paper.
An Integrated Approach to the Modeling of Permeability Barrier Distribution in a Sedimentologically Complex Reservoir
Authors: Martin J. H. , Cooper J. A. 
Published: December 2007

ABSTRACT
In a complex clastic reservoir of glaciodeltaic origin - the target for a steam-drive pilot project - low permeability ‘baffles’ seen in cores are difficult to correlate between wells. Their distribution is estimated probabilistically incorporating analogue outcrop data. The resulting model was used to calculate effective vertical permeability to oil, water and steam and to construct a 2-D reservoir simulation model used to determine optimum injection intervals.
Single-Well Pressure Testing Solutions for Naturally Fractured Reservoirs With Arbitrary Fracture Connectivity
Authors: Wijesinghe Aanda M. , Culham Wilmer E. 
Published: December 2007

ABSTRACT
Traditional pressure testing models for naturally fractured reservoirs assume that the rock formation is heavily fractured to an extent that the matrix blocks are completely surrounded by fracture surfaces. Thus, the matrix blocks are unconnected and fluid transport over macroscopic distances can take place only in the fracture network. The model presented here overcomes this deficiency by allowing for matrix and fracture network permeabilities over macroscopic distances; it is thus able to represent moderately fractured formations as well as the limiting cases of unfractured and heavily fractured formations. Also, a new unsteady interporosity fluid flow formulation, which accounts for independent variation of the matrix and fracture system pressures is employed in this model. This feature has not been included in previous interporosity flow formulations.
Analytical solutions and type curves for single-well pressure tests in one, two and three dimensional fluid flow configurations in unbounded domains are presented. Interporosity fluid transfer is modelled using the standard unsteady flow models and the new unsteady interporosity flow formulation. The effects of well bore storage and of the matrix and fracture system skin factors on constant rate drawdown well tests are illustrated through numerical examples. The significance of the special features of this model, namely, that of modelling the macroscopic permeability of the matrix system in addition to that of the fracture system and of using the new unsteady interporosity flow model is demonstrated. The numerical results show that, for moderately fractured formations, significant errors are incurred in the predicted formation properties when matrix block connectivity and the resulting direct fluid transport between matrix blocks are neglected. Also, the results show that the dependence of interporosity flow on the independently varying matrix and fracture system pressures must be accounted for in the interporosity flow model.
Relationship Between Foam Stability Measured in Static Tests and Flow Behavior of Foams in Porous Media
Authors: Maini B. B. , Ma V. 
Published: December 2007

ABSTRACT
Selection of a suitable foaming agent for mobility control in steam floods requires screening a large number of available surfactants. Many different screening strategies have been reported in the literature for this purpose. Almost all of them rely on some type of foam stability measurement for initial screening. However, the relationship between such foam stability measurements and the flow behavior of foams in porous media under steam flood conditions has not been thoroughly investigated. The objective of this study was to determine whether or not a correlation exists between the foam stability index measured in static tests and the mobility reduction characteristics measured in a porous medium.
Foam stability tests were performed under ambient conditions and under conditions of high temperature (200°C) and pressure (6.9 MPa). Foams were generated by injecting nitrogen gas through a gas sparger submerged under the test solution in pressure vessels equipped with glass windows. Subsequent drainage of liquid from the foam as well as rate of decay of the foam volume were then monitored. The mobility control characteristics were measured at 200°C and 6.9 MPa by monitoring the pressure drop across a 30 cm long and 5.7 cm diameter core composed of unconsolidated sand during steady-state flow of foam through the core. Various foams were compared in terms of their mobility reduction factor which represents the ratio of pressure drop across the core at given flow rates of the foaming liquid and gas to the pressure drop obtained at identical flow rates with pure water and gas.
The results show that foam stability measurements made under ambient conditions do not provide an indication of how the foam will perform at high temperature. However, foam stability measurements performed at high temperature and pressure are generally a good indicator of the mobility reduction factor. When comparing different concentrations of the same surfactant, the concentration which provided the maximum foam stability also gave the highest value of mobility reduction factor. When comparing different surfactants, a fairly good correlation was found between the foam stability index and the mobility reduction factor.
Replacement Costs of Domestic Crude Oil
Authors: Kuuskraa V. A. , Morra F. 
Published: December 2007

ABSTRACT
The United States has a rich base of petroleum resources, but replacing domestic oil reserves will be costly and will require advances in technology. In the mature onshore and offshore regions, the bulk of the future oil will be found in small fields. The promise of large discoveries lies in the costly and challenging deep offshore waters and the hostile Arctic. With significant investment in R&D, advanced tertiary recovery methods could also make a major contribution to lower-cost domestic supplies.
The study of the replacement costs of domestic crude oil shows that adequate supplies of lower cost oil could be available through the middle of the 1990s. However, as these lower-cost sources are depleted, replacement costs will begin to escalate rapidly, reaching very high levels after the turn of the century.
Controlling Incompatibilities of Formation and Kill-Weight Fluids during Workover
Authors: Riley S. M. , Potter G. F. , Holmes J. M. , Reeves H. C. 
Published: December 2007

ABSTRACT
Previous attempts to kill water injection wells with calcium-base fluids for workover operations have been unsuccessful due to incompatibilities between the kill fluid and the formation water. Special engineering procedures, supported by comprehensive laboratory screenings, make these operations possible without the formation of damaging precipitates. Laboratory results have demonstrated that scale precipitation can be prevented for at least 10 days with no formation damage. Field data support these results.
Stability Fronts of Permanent Form in Immiscible Displacement
Authors: Jerauld G. R. , Davis H. T. , Scriven L. E. 
Published: December 2007

ABSTRACT
The theory of stability of plane saturation fronts of permanent form in mathematical models of immiscible displacement that was presented in SPE 12691 is developed further. Stability of the saturation profile to normal modes of smal1-amplitude perturbations in pressures and saturation is found by solving the generalized eigenproblem to which linear stability analysis leads. Adaptive discretization into subdomains, simple finite element basis functions, and the Galerkin method are used to compute the growth or decay rate of incipient fingers of small and moderate width across the front. An expansion for large wavelengths is used to derive an analytical formula for the growth or decay rate of very wide fingers.
A generalized mobility ratio, the sum of the mobilities of the two phases far behind the front divided by the sum far ahead, proves to be the first determinant of front stability: ratios larger than unity indicate instability and less than unity, stability. Gravity acting on the density difference between the phases is the second determinant. Incipient narrow fingers are always damped by capillary pressure gradient-driven flow. When the front is unstable there is a fastest growing wavelength, or width of incipient finger — a most dangerous mode. The growth rate of a given wavelength disturbance depends on its length in the flow direction. The greater that length, the faster growing a disturbance of given wavelength. Thus the results indicate that (1) stability depends on the dimensions of the reservoir or core being modeled, and (2) rate of development of fingering depends on the lengths of heterogeneities that disturb the flow.
Sweep Improvement Scoping Studies
Authors: Fussell L. T. 
Published: December 2007

ABSTRACT
Results of a series of reservoir performance predictions investigating simulated effects of sweep improvement methods on oil recovery and economic benefit are presented. In all predictions, the simulated recovery method was an alternate gas-water injection process with operation under parting pressure assumed. Both reservoir modification and process modification techniques are considered as well as variations in treatment interval, reservoir description, gas-water injection ratio, and operating costs.
These studies indicate selective placement of sweep improvement agent is the most important requirement of the variables considered in effecting a successful sweep improvement treatment. Improved oil recovery was predicted for applications with selective placement in reservoirs described with noncommunicating zones, with significant economic improvement dependent on increased gas-water injection ratio and/or high operating costs. Most simulations of sweep improvement applications in reservoirs described without flow barriers between zones resulted in reduced oil recovery and poor economic performance.
A New Fracture Gradient Prediction Technique that Shows Good Results in Gulf of Mexico Abnormal Pressure
Authors: Brennan R. M. , Annis M. R. 
Published: December 2007

ABSTRACT
Accurate formation fracture gradient prediction in abnormally pressured wells is one of the most critical considerations involved in planning a successful drilling operation. Shallow abnormal pressure, coupled with deep geologic objectives, requires an accurate fracture gradient prediction to insure casing setting depths are correctly determined in order to carry sufficient mud weights to successfully reach the deep objectives. In an effort to better meet these requirements, a study of formation fracture gradients was made for the Western and Central Gulf of Mexico. As a result of this study, a new technique was developed which accurately predicts fracture gradients in the abnormally pressured formations. This technique is based on an empirical correlation of Effective Horizontal Stress Gradient to Effective Vertical Stress Gradient.
A Reservoir Simulator Based on the Method of Characteristics
Authors: Hales H. B. 
Published: December 2007

ABSTRACT
A two-dimensional, two-phase, incompressible reservoir simulator has been developed with a solution method based on characteristic theory. The model has been benchmarked against traditional finite difference simulators with four simple problems. The results suggest that new the method is greatly superior to finite difference methods. At equal accuracies the characteristic model is estimated to be much faster than finite difference models, often by several orders of magnitude.
Determination of Hydraulic Fracture Azimuth by Geophysical, Geological, and Oriented-Core Methods at the Multiwell Experiment Site, Rifle, CO
Authors: Teufel L. W. , Hart C. M. , Sattler A. R. , Clark J. A. 
Published: December 2007

ABSTRACT
A comprehensive program for prediction of hydraulic fracture azimuth is being conducted in the tight, lenticular, gas sandstone reservoirs of the Mesaverde Group in the Department of Energy's Multi-Well Experiment near Rifle, Colorado. Methods used in the program can be divided into two groups: 1) indirect, predictive techniques which determine either the principal paleo-stresses or in situ stresses prior to fracturing and 2) direct observation from either geophysical detection and mapping of hydraulic fracture propagation or wellbore impression-packers of open-hole hydraulic fractures. Predictive methods which determine the paleo-stress directions include geologic observations of the orientation of normal faults and fractures at the surface and in oriented core and twinned calcite strain analysis of oriented core. These methods show a consistent direction of N 75°W ± 10° for the maximum horizontal paleo-stress. Predictive methods which determine the in situ stress directions include 1) oriented core analysis using anelastic strain recovery measurements and differential strain curve analysis, 2) oriented caliper and televiewer logs to infer stress directions from wellbore breakouts, and 3) computer modeling of the horizontal stress directions due to gravitational loading of topographic relief. The results of these methods are fairly consistent, and are in general agreement with the paleo-stress results, but also suggest a possible 20° clockwise rotation with depth of the maximum horizontal in situ stress from N 89°W ± 10° in the upper fluvial zone starting at 1330 m to N68°W ± 9° in the marine zone ending at 2450 m. The clockwise rotation of the horizontal stresses with depth may be due to large, local topographic relief superimposed on the regional stress field of the basin. Confirmation of the predicted fracture azimuth in the paludal zone at 2100 m was made using a borehole seismic detection method during hydraulic fracturing, which incorporated an observation well that was within 80 m of the stimulation well. The fracture height and azimuth was mapped for 3 different fracture tests and showed a mean azimuth of N 67°W ± 8°. In addition, an open-hole hydraulic fracture test in which impression packers were used, showed a fracture azimuth at the wellbore ranging from N50°W to N 70°W in the marine zone at 2306 m.
The Evaluation of Uncertainty in Surfactant EOR Performance Prediction
Authors: Brown C. E. , Smith P. J. 
Published: December 2007

ABSTRACT
This paper describes a method for evaluating the uncertainty in Surfactant Enhanced Oil Recovery performance prediction given the intrinsic variability in the physical properties which govern the displacement process. This work forms a stage in the detailed assessment of the economic viability and associated risk of an EOR project. The method uses Monte Carlo simulation techniques to calculate the probability distributions of key output variables: (i) breakthrough times (ii) displacement efficiency (iii) oil cut. The uncertainty associated with the performance prediction is derived from probability distributions to define the variations in: (a) adsorption (b) residual oil saturation to water and surfactant and (c) the shape of the surfactant relative permeability curves. The probability distributions are generated from laboratory core data, and the partial dependency between parameters specified from knowledge of the chemical displacement process. Each replicate evaluation requires the determination of the output variables (i) - (iii) using fractional flow theory, given a correlated random sample of the parameters (a) - (c). The results illustrate the importance of allowing for uncertainty in predicting EOR performance. The extension of this stochastic modelling technique to describe the effects of reservoir heterogeneity is discussed.
Using Ultraviolet Radiation for Controlling Sulfate-Reducing Bacteria in Injection Water
Authors: Clark J. B. , Luppens J. C. , Tucker P. T. 
Published: December 2007

ABSTRACT
Laboratory and field experiments have shown that ultraviolet light may be as effective a treatment for microbial control in injection waters as many biocides. In many cases, the use of ultraviolet light is less expensive. The ultraviolet unit must be properly designed and constructed, and the effectiveness of the unit must be determined by a bioassay rather than by Ohysical measurements. Experimental results are presented and recommendations for design and use of ultraviolet units are given.
Fishing
Authors: Walker G. 
Published: December 2007

ABSTRACT
Any object dropped or stuck in a well that interferes with it's normal operations is called a fish and must be removed from the well. The operation of removing these objects is called a fishing job. When we are involved in a fishing job, we simply say – "We are fishing".
Why or when these terms were first used, no one seems to know, but there are some similarities. We use a long line (the work string). The fish cannot be seen, but we do have to catch it (engage it) before the fish can be pulled out. I cannot think of any better terms, so let's go fishing.
Fishing jobs are put into two classifications, open hole and cased hole. When there is no casing in the area of the fish, it is called open hole fishing. When the fish is inside casing, it is called cased hole fishing. There are numerous kinds of fishing jobs. Wash over job, overshot run, spear run, stripping job, jar run, --that's just a few.
There are many things that can become a fish -- stuck drill pipe, broken drill pipe, drill collars, bit, bit cones, hand tools dropped in the well, sanded up or mud stuck tubing, packers become stuck, and much more. Wire line broken or stuck in open hole or cased hole can create a bad fishing job. There are many other things that can develop into a fish and many other causes that create a fishing job that haven't been mentioned here.
Since there is so many different kinds of fish and fishing jobs, there are many different tools and methods to do the job. Some of the tools are very simple and some are very complex.
There are no two fishing jobs alike, yet there are lots of fishing jobs similar. An experienced fishing tool man will draw from the experience he has gained on each job.
It is very important on a fishing job for all parties involved to cooperate with each other. It is important for the fishing tool people to obtain all the information concerning the well. That way they can can select the right tools and methods to clean the well out as quickly as possible.