bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effectiveness of Fluid Loss Additives in Laboratory Dynamic Fluid Loss Experiments
Authors: Charles Dawari D. , Xie Xiaopeng 
Published: December 2007

ABSTRACT
A commercially available HTHP (high temperature, high pressure) dynamic filtration unit and a widely available HTHP rheometer was used to study dynamic fluid-loss behavior of uncrosslinked hydroxypropyl guar hydraulic fracturing fluid containing varying concentrations of silica flour, starch, and diesel.
New dimensionless groups were defined for the dynamic fluid-loss problem. These groups were used first to effectively correlate previously reported laboratory data and later were employed to analyze the ensuing experimental data.
Results demonstrate that low and high permeability cores require different mechanisms for fluid-loss control and that, compared to silica flour, starch may loss its effectiveness at higher concentrations.
Tests Confirm Operational Status of a Large-Slot Flow Apparatus for Characterizing Fracturing Fluids
Authors: Shah Subhash N. , Lord David L. 
Published: December 2007

ABSTRACT
A large-slot flow apparatus for investigating hydraulic fracturing fluid flow and proppant transport phenomena has been jointly developed by the Gas Research Institute (GRI), the Department of Energy (DOE), and The University of Oklahoma. A series of tests were performed to confirm the operational readiness of this apparatus to perform the many functions for which it was designed. This paper describes results obtained from the verification tests, particularly in terms of the proper functioning of instrumentation and control systems under a wide range of operating conditions. Tests performed were: flow of crosslinked gels, high-temperature (200 and 225pF) flow tests, high-pressure (1,000 psi) flow tests to confirm proper operation of a unique throttling valve, effect of pressure on perforation pressure loss, and dynamic fluid-loss tests with permeable facings at 1,000 psi.
Verification tests listed above were performed and the large-scale, high-pressure, fracture-flow simulator was found to be fully functional in nearly every respect. Functionality was established by comparing flow data from the simulator to conventional viscometric results whenever possible. Some surprises, in terms of both flow cell response and fluid behavior, were found during the course of verification testing. For example, there was the discovery that crosslinked gels exhibit a slip-like flow phenomenon in the simulator. This latter phenomenon was discovered while using the variable width capability of the apparatus. A methodology was developed which allows collection of meaningful flow data in the presence of this slip-like phenomenon. An additional surprise was the discovery that there was no effect of elevated pressure on the perforation pressure loss, as some industry critics have suggested.
Flow Visualization of Flow Into 8 Point-Source Fractures II: The Effect of Fracture Non-Uniformity and Fluid Crosslinking
Authors: Clark P. E. , Zhu Quisheng 
Published: December 2007

Abstract
Recently, the flow of fluids into a fracture from a point source has been the subject of several different papers. Cleary and Fonseca1 first suggested that convective transport should play a major role in the placement of proppant when the flow into a fracture was from a point source. Clark and Courington2 presented data showing that for non-viscosified fluids convection was the dominant mechanism of transport. However, they showed, that for uniform fractures, viscosifying the fluid made a large difference in the transport mechanism. In a later paper, Clark and Zhu3 presented data for non-uniform fractures and viscosified fluids weighted with either salt or silica flour that showed that the presence of minor non-uniformities serve to negate the effect of convection even more than viscosifying the fluids.
In this work, we have extended the work presented in the previous two papers to high viscosity Newtonian fluids and crosslinked fluids. The experiments have all been done with various concentrations of silica flour to simulate added proppant. Both changing the nature of the non-uniformities and crosslinking the polymer solution have a profound affect on the flow into the fracture and the convective process.
Fluid-Loss Control for High-Permeability Rocks in Hydraulic Fracturing Under Realistic Shear Conditions
Authors: Navarrete R. C. , Mitchell J. P. 
Published: December 2007

ABSTRACT
A study is presented on the effectiveness of different combinations of fluid and fluid-loss additives to control fluid loss in high-permeability formations under high shear rates. The impact on matrix damage and proppant-pack damage is also studied. Borate-crosslinked guars, hydroxyethylcellulose (HEC) and a surfactant water-base gravel packing fluid were investigated. The fluid-loss additive considered was silica flour. All fluid-loss tests were run in dynamic fluid-loss cells. To properly test high-permeability cores, new long core dynamic fluid-loss cells were used. The matrix damage caused by the invasion of the fluid was determined using pressure taps along the core. Conductivity tests were also run to determine the damage to the proppant pack.
Results show that the effectiveness of particulate fluid-loss additives under dynamic conditions is strongly dependent on the initial leakoff rate, which depends on the pressure gradient across the core, permeability of the core and viscosity of the invading fluid. The use of silica flour helps matrix flowback, and it has a minimal effect on proppant-pack conductivity in clean fluids (e.g., surfactant water-base gravel packing fluid). With the exception of the borate-crosslinked guar with no fluid-loss additive, the variety of fluids used in these tests (with and without silica flour) have a negligible effect on postproduction.
The Carbonate Envelope
Authors: Bigelow Edward L. 
Published: December 2007

Abstract
Exploratory well tests typically require timely, yet accurate log analysis from the responsible formation evaluation specialist. A rapid turnaround in the analysis is demanded due to economic considerations and decisions that are routinely made from log-derived, in-place reserve estimates. In general, in-place estimates are quickly expanded to include the reservoir's areal extent that was likely conceived from prior seismic and geological studies. Wireline data usually provide the porosity, saturation, pay thickness, and evidence of producibility that are input into reserve calculations. Core data are seldom available on exploration tests, especially in carbonate reservoirs.
A flexible algorithm defines formation resistivity factor (FR) boundaries within which log measurements from carbonates occur. Evidence shows the n exponent in carbonate reservoirs to be strongly affected by wettability characteristics and porosity type, but tolerable estimates of n can be made to obtain relatively accurate and timely estimates of saturation.
Improved Prediction of Foam Diversion in Matrix Acidization
Authors: Zeilinger S. C. , Wang M. , Kibodeaux K. R. , Rossen W. R. 
Published: December 2007

Abstract
Recent studies of foam-diversion processes for matrix acidization identify gas trapping during post-foam liquid injection as the key to foam effectiveness. Laboratory studies identify two degradation processes during this period: a rapid increase in mobility throughout the core, followed by a slower further rise in mobility starting at the core inlet. New coreflood results indicate that pressure gradient ∇P during the first process is insensitive to a shut-in period after foam injection but depends weakly on liquid flow rate. A small fall in gas saturation accounts for the first rise in mobility, which appears to depend on mobilization of foam bubbles (i.e., on ∇P) rather than foam collapse (i.e., on capillary pressure). The second rise in mobility appears to be due to gas dissolution in injected liquid. Therefore this transition, which is harmful to field performance, can be avoided by including a small amount of gas with the injected acid.
Process modeling illustrates that some designs that appear successful in laboratory linear corefloods can perform poorly in the field due to the geometry of radial flow. The fractional-flow approach, together with coreflood pressure data for multiple sections along the core, provides a uniquely simple and insightful framework for interpretation of laboratory results and extrapolation to the field.
The simple diversion model of Hill and Rossen1 can successfully model foam processes in which the secondary degradation of foam during liquid injection is avoided by including gas with the acid.
Economics of Research
Authors: Faull R.F. 
Published: December 2007

Abstract
Research has become essential to maintain the health of a modern-day, technically oriented company; yet, on a project-by-project basis, research is a project-by-project basis, research is a high-risk operation. In oil exploration and production, research is a team effort not easily separated from operations. Based upon 25-years of experience, it appears that research is resulting in a very attractive economic return.
Attempts to evaluate and select research projects by analytic approaches have not projects by analytic approaches have not been particularly successful. Reliance, therefore, must be on judgments, both technical and business, to determine total size of the research program as well as the nature and priorities of individual projects. Several factors related to spreading the risk and taking advantages of technical opportunities are reviewed.
Research demands to meet increased petroleum requirements of the future will petroleum requirements of the future will surely increase. More industry cooperative type projects seem to be one step in controlling industry costs.
Introduction
When your program committee asked that I discuss the economics of research today, I accepted the request as a challenge, knowing that it is a subject not easily settled with either straightforward analyses or broad generalizations. Research is a high-risk business with many "dry holes," and neither the selection of lines of investigation nor evaluation of results can be handled with mathematical exactness. If you came expecting me to offer some fancy formulas for doing so, I'm afraid you will go away disappointed.
The very first problem in approaching the subject of economics of research is that research is not a separable part of a complex, industrial activity. This is more or less true in any modern, technically oriented business; but I believe it is particularly so in oil exploration and production and perhaps equally so in other mineral recovery industries. In our business, research and field activities blend or interfinger almost continuously.
Production Optimization of Sucker Rod Pumping Wells Producing Viscous Oil in Boscan Field, Venezuela
Authors: Guirados Carlos , Sandoval Jose , Rivas Olegario , Troconis Henry 
Published: December 2007

Production Optimization of Sucker Rod Pumping Wells Producing Viscous Oil in Boscan Field, Venezuela,

Abstract
Boscan field is located in the western coast of Maracaibo lake and is operated by MARAVEN S. A., affiliate of Petroleos de Venezuela S. A. It has 315 active wells, 252 of which are produced with sucker rod pumping. Other artificial lift methods currently applied in this field are hydraulic (piston) pumping (39 wells) and ESP (24 wells).
The history of this field reveals the existence of several operational problems which preclude the optimum production of the sucker rod pumping wells. The main problems, however, are related to the hish frictional forces that arise between the rod string and the crude oil being produced since average crude gravity is 10 degrees API.
This paper presents the results of the production optimization of two sucker rod pumping wells of Boscan field producing viscous oil. This optimization has been possible due to the development of a new production scheme and the application of system analysis in completion design. The new production scheme involves the utilization of a subsurface stuffing box assembly and a slotted housing, both designed and patented by INTEVEP S. A., affiliate of Petroleos de Venezuela S. A. The completion design method and software used in the optimization study were also developed by INTEVEP S. A.
The new production scheme and design method proved to be effective in preventing the causes of the above mentioned problems, allowing the increase of oil production under better operating conditions.

Introduction
Venezuela is one of the main oil producers of the world. Many of this oil production is made of heavy oil and bitumen. In fact, Venezuela possesses the largest accumulation of heavy oil and bitumen of the world: The Orinoco Field Belt. Some other important Venezuelan heavy oil fields are: Melones, Ovejas, Morichal and Jobo located in the eastern region of the country, and Tia Juana, Lagunillas, Bachaqueros and Boscan, in the western region, around the Maracaibo lake.
Each one of this fields has particular characteristics, and operating criteria. All of them, however, have two common characteristics in relation to artificial lift of the viscous oil:
P. 867
Use of Staged Mill and Mechanical Whipstock Saves Sidetrack Time and Cost by up to 50%
Authors: Kirkwood Y. S. , Pritchard M. D. 
Published: December 2007

ABSTRACT
Due to the current marginal economic status of the petroleum industry, drilling a new well is more difficult to justify than ever before. Many Operators have adjusted by recompleting old wells whenever possible. While the use of old wells reduces up front capital investment and alleviates some environmental concerns, the risk to formation damage can be much higher than drilling a new well. Although there are many methods of recompleting old wells, the experience at Mt. Poso indicates that none can provide a cleaner wellbore than a sidetrack completion.
This paper discusses sidetrack operations using redesigned staged mill and mechanical whipstock. These sidetracks were performed in 1800’ wells located at the Mt. Poso field, CA. The staged mill and mechanical whipstock system, called the Sidewinder, and is jointly invented by B&G Machine & Welding shop and Shell Western E&P Inc. The Sidewinder is an enhanced version of the existing whipstock and staged mill technology that is currently overshadowed by the casing section mill. The initial result indicates the new method can reduce both time and cost by as much as 50% over the conventional casing section mill method. The margin of savings is even greater in wells with multiple casing strings.
Thus far, the Sidewinder has been used to sidetrack single and dual casing wells with standard casing sizes. The Sidewinder can be modified to accommodate any non-standard casing sizes also. The greatest benefit thus far has been superior economic success rate due to reduced number of tools and less milling time from sidetracking wells with multiple casing strings. The superior economics have also allowed wells to be recompleted that would have been uneconomic using the conventional casing section mill.
Stimulation Fluid Developement and Applied Fracturing Model Improves Results, Morrow Sandstone, Hutchison County, Texas
Authors: Lehman Lyle V. , Olson Robert , Kelley Charles C. 
Published: December 2007

ABSTRACT
The Morrow formation in Hutchison County, Texas was long considered incapable of producing hydrocarbons at an economic rate. Most post-frac production rates were the same or less than pre-frac rates. Only high flow rate, non-stimulated completions were considered economic, but these completions were few in number. These facts lowered expectations for sufficient recovery of investment necessary to continue developmental drilling.
Utilization of modern fracture model techniques, core analysis, fluid testing and stress data lead to a system of stimulation techniques, fluids and proppants that has created a cost-effective stimulation system for the Morrow formation. Lithology studies showed that the frac fluid was primarily critical to success. These studies lead to an unorthodox fluid. It contained two elements that would not be considered practical in any other formations or circumstances in the Western Anadarko basin. Proppant placement was identified as the second most important issue. Fracture height was found to be controlled by permeability, not stress. This led to the discovery that proppant convection did not allow for good proppant placement. Proppant staging methods were augmented to combat excessive convection and then acquire advantageous proppant placement. Proppant selection was identified as the third most important criteria. Reservoir stresses and modeling showed that high cost, high stress proppants were not necessary. Lower cost, larger sized proppants yielded much higher conductivity than in previous completions.
These criteria were integrated into a solution which brought the post-frac production rate from a one fold to a ten fold increase.
Better Gas Identification in Southwestern Wyoming
Authors: Corbett Joe , Jardon Michael , Crary Steve 
Published: December 2007

Abstract
A new epithermal neutron tool, the Accelerator Porosity Sonde (APS), is being used for improved gas identification in Southwest Wyoming. The APS uses a high-yield electronic neutron source instead of the chemical source used in conventional neutron tools. It has five neutron detectors that provide both thermal and epithermal neutron detection, as well as borehole shielding, to obtain better porosity measurements. These improved measurements are not as sensitive to borehole environments and lithology effects and thus provide better gas determination. The tool has improved vertical resolution, which is helpful in the thin-bedded, shaly gas bearing sands of southwest Wyoming. This paper will discuss the tool features and compare examples of conventional neutron tools versus to this new technology and demonstrate improved identification of pay zones.
Tight Gas Sand Production from the Almond Formation, Washakie Basin, Wyoming
Authors: Iverson W. P. , Surdam R. C. 
Published: December 2007

ABSTRACT
Gas production from the Almond Formation in the Standard Draw trend can only be accounted for by draining numerous layers of tight gas sands via the permeable upper bar sand. Discovery of this field originally focused upon production from this bar sand. But continued development cannot be explained simply by considering depletion of a 30 foot sand. Gas volumetrics verify the need to include lower sands in reservoir analysis. Core obtained from the Almond bar sand confirm petrophysical constants used in our models. Our results imply that economic levels of gas production should be possible wherever a similar horizontal conduit can be tied into gas saturated layers through massive hydraulic fracturing.
Investigations of Matrix-Fracture Transfer Flows in Dual Porosity Modeling of Naturally Fractured Reservoirs
Authors: Chen Jianping , Miller Mark A. , Sepehrnoori Kamy 
Published: December 2007

ABSTRACTIn recent years many research results, both theoretical and experimental, have been published to improve the accuracy of dual porosity modeling. Most of these studies dealt with the accuracy of matrix-fracture transfer flow (MFTF) calculations (so-called transfer functions). Some studies concentrated on creating empirical transfer functions through single matrix block modeling, while others incorporated MFTF calculations in dual porosity model by using some type of sub-gridding or averaging technique. However, flow in fractures and its effects on MFTF have not been fully studied in the literature.In this paper, we first compare methods for MFTF calculations under static fracture conditions, followed by results of numerically modeling fluid flow in matrix blocks with adjoining fractures undergoing dynamic conditions. The system studied is an oil-saturated matrix block surrounded by fractures in which water is injected to generate dynamic flow conditions. Hence, there are two dynamic flow systems. One is counter-current imbibition inside the matrix block, and the other is two-phase flow in the fractures.Results show that MFTF can be characterized by three flow regimes. The first is before water breakthrough at the producing end of the fracture, during which little imbibition occurs inside of the matrix block depending on injection rates. The second is transient flow inside the matrix block. During this flow period the most injected water is imbibed into the block. The last flow regime occurs when flow in both systems approaches a pseudo-steady type behavior. Dimensional analysis shows that two parameters can be used to characterize these flow regimes. One is a global time scale ratio and the other is a storativity ratio. The use of proper boundary conditions imposed on both systems plays a vital role in accurately modeling MFTF. Results show that the usual assumption of phase saturation continuity between matrix block and fracture in a conventional dual porosity model generates erroneous results, especially breakthrough time at producers. Our approach is also successfully used to model published experimental data without any adjustment to measured rock and fluid data.
Simulation of Gas Cycling Using a Beta Model
Authors: Guehria F. M. , May R. S. , Baiar T. E. 
Published: December 2007

ABSTRACT
In this work, we present a field study which indicates that if PVT properties are properly derived, we may be able to use a beta model to history match and predict performance for complex fluid systems. The specific example considered pertains to a field containing a gas condensate fluid column underlaid by a volatile oil leg. Residue gas and nitrogen are continuously injected into four wells completed in the gas condensate column, whereas, 29 wells produce from the oil zone. For this system, we were able to build a two-component beta model that accurately reproduced the same thirty years of reservoir performance as an eleven component compositional simulator originally formulated for history matching and performance prediction.
The intended major contributions of this work are as follows. First, we present a procedure which uses a calibrated equation of state combined with material balance techniques to generate appropriate PVT properties for the beta model. The PVT properties properly account for the variation in saturation pressure from one point to another in the reservoir. Second, we illustrate that a beta model can often be used for history matching and performance for cases where it is commonly believed that a multicomponent compositional model is needed.