bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating Fracture Gradient in Gulf of Mexico Deepwater, Shallow, Massive Salt Sections
Authors: Barker J. W. , Meeks W. R. 
Published: December 2007

Abstract
Drilling massive salt sections in the deepwater Gulf of Mexico is becoming a frequent occurrence. The abundance of salt and the ability of seismic to image under salt have made drilling massive salt sections common place. It is estimated that over a hundred wells in the deepwater Gulf of Mexico have penetrated salt at both shallow and deeper well depths. As the industry gains experience drilling deepwater, shallow allochthonous salt bodies, several advantages of drilling through, rather than around, salt have emerged. Fracture gradients in shallow salt intervals have proven to be much higher than in non-salt sediments at a comparable depth. As a result of the increased fracture pressure, massive salt sections have been used to extend casing points and eliminate casing strings, resulting in greatly reduced well costs through reduced rig time, well tangibles, underreaming, cement volumes, and mud volumes. Many operators are now choosing to drill massive, shallow salt sections to take advantage of these benefits. In some cases these cost savings have the potential of making marginal deepwater reserves economically feasible to develop and produce. A reliable estimate of the fracture gradient in shallow, massive salt sections is needed to design casing strings and plan mud weights for safe and cost effective wells.
Upon exiting a shallow salt zone, often the formation pore pressure and fracture pressure are very close. Typically this condition results in drilling problems including lost returns, well control events, etc. The proper choice of a mud weight to exit a shallow, massive salt section can be a critical factor for both well integrity and cost.
This paper describes a method to estimate the fracture gradient for a salt formation below a casing shoe. The method is based on experience gained while drilling wells which penetrated substantial salt sections. Also presented are guidelines that can help in selecting a mud weight when exiting the bottom of a massive shallow salt section.
Stress Perturbations Adjacent to Salt Bodies in the Deepwater Gulf of Mexico
Authors: Fredrich J. T. , Coblentz D. , Fossum A. F. , Thorne B. J. 
Published: December 2007

Abstract
Lack of consideration of the geomechanical interaction between salt bodies and surrounding formations has led to documented drilling failures adjacent to salt diapirs1–3, in some cases resulting in individual well abandonment costs of tens of millions of dollars. To address this issue, a three-dimensional non-linear finite element geomechanical simulation effort was initiated to analyze the in situ stress state existing in and adjacent to salt bodies before drilling as well as under producing conditions. This work leverages unique expertise in salt mechanics and computational geomechanical modeling. Non-linear finite element geomechanical models were developed for four idealized deepwater Gulf of Mexico geometries including a spherical salt body, a horizontal salt sheet, a columnar salt diapir, and a columnar salt diapir with an overlying tongue. The analyses reveal that at certain locations for specific geometries: shear stresses may be highly amplified; horizontal and vertical stresses may be significantly perturbed from their far-field values; principal stresses may not be vertical and horizontal (i.e., the vertical stress may not be the maximum stress); and anisotropy in the horizontal stresses may be induced. For some geometries, the vertical stress within and adjacent to the salt is not equal to the gravitational load; i.e., a stress-arching effect occurs. Analogously, the assumption that the horizontal stress within a salt body is equal to the lithostatic stress is shown to be incorrect sometimes. The modeling also suggests an alternative explanation for the so-called rubble zones thought to occur beneath and/or adjacent to salt diapirs, in that they may be an intrinsic consequence of the equilibrium stress field needed to satisfy the different stress states that exist within the salt body and in the non-salt surrounding formations. We demonstrate with an example how this work can enable more rigorous planning of well locations and trajectories by providing more accurate estimates of the vertical and horizontal stresses around and within salt bodies for wellbore stability analyses so as to avoid areas of potential geomechanical instability, and to enable accurate fracture gradient prediction while entering, drilling through, and exiting salt bodies.
Hole Cleaning and Cement Design for Specific Formation Types
Authors: Rueda Francisco , Heathman James , Serrano Mario 
Published: December 2007

Abstract
This paper describes a new design procedure developed to help effectively remove drilling fluid components, particularly thick layers of partially dehydrated filter cake, from the casing/wellbore annulus after the fluid has been exposed to downhole conditions, including, temperature, pressure, fluid loss, and static time. This new methodology can be conducted in any properly equipped cementing and drilling fluids laboratory.
To isolate the zones of a well and allow a reservoir to be produced safely and economically, drilling fluid and drill cuttings should be removed from the annulus and replaced by a competent cement sheath that bonds and seals the casing to the wellbore. Simple laboratory tests performed with commercially available testing devices help the designer evaluate the cleaning efficiency of flushes, spacers, and surfactants under simulated downhole conditions. These tests can determine the following parameters:
Force required to mobilize the drilling fluid Chemical effects of preflushes and/or spacers used for mud removal and filter-cake removal and their effect on filter-cake permeability
These parameters, combined with a mathematical model that helps determine the fluid properties and annular velocities required to effectively remove drilling fluid, provide a realistic simulation of the displacement process.
Case histories and well logs illustrate how the displacement process can be significantly improved when designers use a procedure that includes the following steps:
Conduct laboratory tests. Run a mathematical simulation model. Design fluids to address issues such as cementing across unconsolidated and/or high-permeability formations.
The Use of Lightweight Cement Slurries and Downhole Chokes Improves the Success of Primary Cementing on Air-Drilled Wells
Authors: Brown Devin , Ferg Thomas 
Published: December 2007

AbstractThe success of a primary cement job is often measured according to effective zonal isolation, achieving the designed top of cement and avoidance of remedial cementing. In the San Juan and Rio Arriba Counties of New Mexico, many Mesa Verde and Dakota wells are air-drilled because the Mesa Verde formation is sub-normally pressured and is naturally fractured. This combination makes the Mesa Verde easy to hydraulically fracture during normal drilling and cementing operations. Therefore, meeting the primary cement job success criterion is particularly challenging.Cementing of casing within an air-drilled wellbore allows the slurry to free fall. Cement-free fall can cause severe surge pressures at the bottom of the hole, leading to hydraulic fracture initiation and loss of lift. The use of a downhole choke can be employed to prevent these processes from occurring.Because mud filter cake does not exist in an air-drilled hole, the lead water spacer and cement must wet the casing and wellbore rock surfaces. Loss of the lead water spacer in conjunction with cement water loss can produce dehydration of the cement column, leading to an increase in cement viscosity and equivalent circulating density. Careful control of cement-free water and fluid loss are required to prevent this from occurring. Furthermore, placing cement across targeted completion intervals which have low fracture gradients requires the use of a high-compressive strength, low-density cement which is competent and capable of maintaining zonal isolation during the completion and production phases of well construction.This paper will outline the evolution of the cementing practices used for the Mesa Verde and Dakota wells drilled in the 29-6 Unit (T29N – R6W, New Mexico) from 1998 to 2002. It will illustrate how cementing changes enabled the primary cementing to be successfully completed in a single stage instead of two, which has translated into cost savings for both the drilling and completion phases of a well. The impact of using a downhole choke for the pumping and placement of these primary cement jobs will be illustrated and discussed. The function of the cement additives on slurry properties will also be discussed as they pertain to these cement jobs.
Using Multicomponent Seismic Data to Better Understand Reservoir Characteristics
Authors: Waggoner John , Kristiansen Pål 
Published: December 2007

AbstractMulticomponent (3C on land/4C on seabed) seismic data has unique information content that has proven to be useful in structural interpretation. As such, development of 3C/4C seismic acquisition, processing, and interpretation systems has increased over the past few years within the geophysical community. These improvements have shown that 3C/4C seismic information has application beyond structural interpretation, and can reveal internal reservoir characteristics that are directly useful in understanding and managing the reservoir.After reviewing the principles, applications, benefits, and recent advances in 3C/4C seismic technology, all from an engineering perspective, this paper concludes that 3C/4C seismic has utility beyond the known niche applications, such as gas cloud imaging, to applications with broader benefit, such as fracture characterization and drilling hazard identification, as well as better reservoir property prediction and the ability to discriminate lithology (sand/shale) and fluid (water, gas, fizzy water). These conclusions are illustrated with recent case studies.
Design and Construction of Pilot Wetlands for Produced-Water Treatment
Authors: Jackson L. M. , Myers J. E. 
Published: December 2007

Abstract
Wetlands are not well understood by the oil industry, environmental contractors and regulatory agencies. The pilot and full-scale treatment performance data sets to properly design wetlands do not exist in public domain literature. Wetland design equations based on the average of the bad and good data sets create wetlands that are almost never sized properly. Engineers trained to work with "black box" treatment technologies tend to shy away from the "green box" treatment technologies. The treatment performance of pilot wetlands ranges from poor to excellent, in part, due to a lack of understanding of what wetlands can do and of how to effectively conduct pilot wetland studies. The impetus for this three-year wetland pilot study is to build an operational knowledge of treatment wetlands and to obtain a data set that can be used to redesign a full-scale wetland for produced water treatment.
Free-water surface (FWS) and subsurface flow (SSF) pilot wetlands were constructed. The wetlands were operated outdoors to test climatic influences and simulate real-world conditions. This paper presents and compares the design, construction, operation and data collection of FWS and SSF pilot wetlands. This treatment wetland paper covers the first two years of a three-year cooperative research and development agreement (CRADA) between DOE and ChevronTexaco. It includes water quality, troubleshooting, lessons learned and pilot operations with summer students. We will also explore the merit and associated effectiveness of treatment wetlands for small and large-scale oilfield operators.
The New Small-Drillhole Minipermeameter Probe for In-Situ Permeability Measurement
Authors: Dinwiddie C. L. 
Published: December 2007

Abstract
Laboratory measurement of permeability using a Hassler cell is the industry standard; however, consistently removing un-disturbed rock samples from friable outcrops is difficult. Al-though conventional surface-sealing minipermeameters have been developed as an alternative for permeability measure-ment, these devices suffer from difficulties in maintaining optimal forces on the tip-seal when dealing with outcrop ir-regularities in the field; outcrop weathering is also problem-atic. Because a reliable field method is needed for outcrop studies, this paper presents an innovative technique for meas-uring permeability in situ. The design of a new small-drillhole minipermeameter probe is discussed, as well as the accompa-nying analytical technique and the size and shape of the in-strument's averaging volume. Small diameter holes [i.e., 1.8 cm (0.7 in)] are drilled into an outcrop with a masonry drill, followed by drillhole vacuuming, probe insertion, seal expansion, gas injection, and calculation of the intrinsic permeabil-ity through measurement of the injection pressure, gas flow rate, and knowledge of the system geometry. Advantages of this approach are the elimination of questionable measure-ments from weathered outcrop surfaces, provision of a supe-rior sealing mechanism around the air injection zone, and the potential for permeability measurement at multiple depths below an outcrop surface. To date, data have been collected from three diverse porous media: upper and lower shoreface sandstone (Escalante, Utah), saprolitic soils (Clemson, South Carolina), and nonwelded tuff (Bishop, California). The probe has proved durable and robust, with a single probe being suffi-cient to make thousands of measurements in a variety of envi-ronments. Data quality supports the conclusion that the drillhole probe is a practical field instrument.
Four-Term Decomposition Techniques for a Faster Inversion of Induction Responses
Authors: Hardman Richard , Fanini Otto 
Published: December 2007

Abstract
We present a technique to decompose the computed response of an induction log and most other logs into four separate mathematical terms and suggest how these terms could be utilized in faster inversions. A challenging requirement for the interpretation of resistivity measurements is the availability of fast and accurate results presented in real-time in the logging unit for better casing decisions at the well site and the later formation evaluation. This challenge has taken new dimensions as formation evaluation targets have evolved from homogeneous to layered media, from vertical to deviated wells and from isotropic to anisotropic formations. The industry has previously addressed these interpretation challenges of induction measurements with two main approaches. These measurements are either deconvolved with filters or inverted with forward modeling in an attempt to obtain the true formation resistivity.
The inverse filter deconvolution approach based on Doll's vertical geometric factors (Doll 1949)1 is fast and suitable for thick layers and vertical wells (Barber 1985).2 Thin bed and dip effects impose serious limitations on the filters. Forward model based correction charts (Hardman and Shen 1987)3 are limited to three beds. In recent years geophysical data inversion has been increasingly used and an industry overview has been presented in the literature (Lines, editor 1988).4 The least square inversion method for induction data (Lin et al. 1984)5 has been also reviewed (Lines and Treitel 1984).6 Maximum likelihood and maximum entropy methods were developed in the fields of information theory (Shannon 1949)7 and imaging (Frieden 1972).8 Inversion of induction log data utilizing a maximum entropy technique (Dyos 19869, Freedman and Minerbo 199110) has been generalized to other resistivity data including multiple frequency and multiple array induction data. The main limitation of this iterative approach is the amount of time consumed by the derivatives computation (Barber et al. 1999).11
This paper describes a method utilizing the four terms resulting from the decomposition of the induction response (Hardman's patent application). This method enables the acceleration of resistivity inversion for vertical and deviated wells including traditional and newer multi-component induction data. The equations used by this method are shown and developed in this paper. The advantages of this method are clearly demonstrated for typical induction log interpretations utilizing inversion methods based on forward modeling. In a broader log context, the method is also relevant to the inversion of other logs that satisfy the diffusion (pulsed neutron logs), the Poisson (electric logs) and the wave equations (sonic logs).
Reserve Analysis for Multilayered Tight Gas Reservoirs
Authors: Cox Stuart A. , Stoltz Ronald P. , Wilson Allen S. , Sutton Robert P. 
Published: December 2007

Abstract
This paper presents an extension of the previous work by the authors1 to examine common reserve analysis techniques for non-communicating multilayered tight gas reservoirs. Tight gas reservoirs present unique challenges to the practicing reservoir engineer. One significant problem is estimating ultimate recoverable reserves for a tight gas reservoir. The extended time required to establish boundary dominated flow in the tight gas systems conflicts with the need to accurately estimate performance-based recoverable reserves early in the life of the well. One other complicating factor is the application of single layer solution techniques to the multilayered commingled completion.
Conceptual simulation cases are presented as a control set to test the accuracy of each analytical method. The simulation results are also used to test various methods of predicting the time required to establish boundary dominated flow in multi-layered, commingled completions. The two simulation cases under consideration are a uniform drainage area and a channel system. Well performance analysis is evaluated during both early time transient and late time boundary dominated flow. A field example is included comparing the results of each technique through time.
Water Vaporization in Gas Reservoirs
Authors: Zuluaga E. , Monsalve J. C. 
Published: December 2007

Abstract
Experiments have been performed to determine the rate of water vaporization in core samples at initial water saturation. The effect of pressure on rate of water vaporization has been studied. The experiments indicate that as pressure decreases from 2000 to 1000 psi, at constant temperature of 90°C, the rate of water vaporization increases from approximately 0.016 to 0.025 g/min. The effect of increase in temperature from 90°C to 100°C, at constant pressure of 1500 psi, is to increase the rate of water vaporization from 0.018 to 0.029 g/min. All the experiments were performed with the core samples at initial water saturation of 18%. As vaporization takes place, the brine remaining in the core sample becomes more concentrated. If concentration exceeds the critical supersaturation value, minerals will precipitate out into the formation. Additionally, the effect of salt precipitation on absolute permeability was determined. The results indicate that reduction in absolute permeability after the vaporization experiments ranges from approximately 14 to 30%.
Low Density, Lost Circulation Control Slurry Utilizing a Unique LCM Allows Successful, Single-Stage Cementing of Extremely Long Production Intervals in the Appalachian Basin
Authors: Mack David J. , Kendrick Daniel 
Published: December 2007

Abstract
The southern West Virginia area of the Appalachian Basin has numerous productive intervals within a single wellbore. The deepest of these is frequently the Rhinestreet member of the Lower Devonian Shale and the shallowest is the Maxton Sandstone or occasionally the Ravencliff Sandstone. The vertical distance between the top and bottom formations ranges between 3000 and 5000 feet.
In addition to the long completion interval, the lower portion of the Devonian Shale can be naturally fractured and exhibit a very low fracturing gradient of 0.4 psi/ft or less.
For a typical 6,500 ft Shale well with a 0.4 psi/ft fracturing gradient, a single stage cementing job covering 5000 ft, would require a conventional slurry with an equivalent density of 10.0 ppg. In an effort to achieve this much annular fill in the past, many cement slurries and techniques have been attempted, including foam cement and 2-stage operations. However, none of these measures routinely exhibited a high success rate at an acceptable cost.
This paper presents laboratory and field data for a unique, low density, high yield cement slurry that, when coupled with a unique, man-made lost circulation material, has routinely demonstrated 4000 ft to greater than 5000 ft of annular fill, at an acceptable cost in a single cementing stage.
Low Polymer Energized Fluid in the Arkoma Basin, Western Arkansas: A Case Study in the Gragg Field
Authors: Carman Paul S. 
Published: December 2007

Abstract
As with all mature petroleum fields, reservoir depletion becomes a factor, especially for wells drilled later in the life of the field. When the reservoir pressure becomes low, standard treatment fluids cannot be used effectively and other methods must be used to stimulate the reservoirs. The Arkoma Basin of Western Arkansas is no exception to this rule. This area of the basin is highly faulted and compartmentalized, which adds significantly to the reservoir complexity. Depending on well placement, there are several potential zones in each well exhibiting varying degrees of reservoir depletion.
The fracturing industry has gone through many technological advances over the years, and with these technological improvements have come many successes. Use of a low polymer energized fluid provides a good solution for these low reservoir-pressure reservoirs. These new style treatments provide faster cleanup, better flowback, better sand placement, and better production than conventional or previously utilized fracturing fluids.
The case studies will show that the low polymer energized fluid technique provides a positive response for these types of wells. Low polymer energized fluids can offer the qualities and properties to enhance completions and improve project and well economics.
Actual Field Data Show that Production Costs of Polymer Flooding can be Lower than Water Flooding
Authors: Wang Demin , Zhao Lanshui , Cheng Jiecheng , Wu Junzheng 
Published: December 2007

Abstract
Daqing Oil Field started industrial scale polymer (polyacrylamide) flooding in 1996. More than 3,000 wells are on polymer flood. The cumulative production by polymer flood is more than 400 million bbl, and annual production of year 2002 about 80 million bbl.
Actual field economic data show that the total cost (including depreciation) per bbl of polymer oil is about $9, the same as water flooding in the same area. Analysis of the data show that high incremental recovery (about 12% OOIP – original oil in place), high production rate (about 4 times that of water flooding) and low water oil ratio (a decrease of about 5 fold) are the main reasons polymer flooding obtained such good economic results.