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- active well (1)
- analysis (1)
- angle (1)
- approach (1)
- approximation (1)
**arbitrarily (7)**- arbitrary vertical cutoff (1)
- Artificial Intelligence (1)
- Bessel function (1)
- Blackhawk (1)
- body (2)
- body angle (1)
- Body System (1)
- boundary (2)
- boundary well (1)
- case (1)
- center (1)
- closure (1)
- coefficient (1)
- complex reservoir (1)
- Computation (1)
- contact (1)
- curve (1)
- demagnetization (1)
- demagnetization effect (1)
- direction (1)
- drag (1)
- Drillstem Testing (1)
- drillstem/well testing (1)
- dynamic programming traveltime (1)
- effect (2)
- elastic wave (1)
- equation (1)
- facies (1)
- field (2)
- Field Experiment (1)
- flow in porous media (1)
- Fluid Dynamics (1)
- formation (1)
- formation evaluation (1)
- Fourier (1)
- fracture (1)
- fracture initiation (1)
- gradational (1)
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- horizontal well (1)
- Houston (1)
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- image well (1)
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- integral equation (1)
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- Reservoir Characterization (4)
- reservoir description and dynamics (6)
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**File Type**

This paper reviews the history of lithostratigraphic and sequence stratigraphic methods and naming schemes. The paper shows that use of arbitrary boundaries in defining lithostratigraphic units in the 50''s resulted in a confusing proliferation of different names for lithofacies of the same age. Early versions of sequence stratigraphy also failed, because of insistence on definitions using arbitrary vertical cutoffs. Seismic stratigraphy fundamentally transformed the science of stratigraphy by providing vastly superior images that allowed correlation of genetically related chronostratigraphically significant units. Reflection seismic data thus provided the key technological breakthrough that provided continuous cross sectional views of stratigraphic basin fills and fundamentally revitalized the science of stratigraphy

arbitrarily, arbitrary vertical cutoff, Blackhawk, boundary, contact, facies, formation, gradational, Houston, international exposition, mallory, member, Reservoir Characterization, reservoir description and dynamics, sandstone, seismic processing and interpretation, seismic revolution, seismic stratigraphy, sequence, sequence stratigraphy, shale, stratigraphy, Upstream Oil & Gas, Wheeler

Oilfield Places:

- Oceania > Papua New Guinea > Foreland Basin > Toro reservoir (0.99)
- North America > United States > New Mexico > San Juan Basin > San Juan Basin Field > Mancos Formation (0.99)
- North America > United States > Colorado > San Juan Basin > San Juan Basin Field > Mancos Formation (0.99)
- Europe > Norway > Norwegian Sea (0.98)

SPE Disciplines: Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)

No preview is available for this paper.

Abstract

The hydraulic fracturing of arbitrarily oriented and horizontal wells is made challenging by the far more complicated near-well fracture geometry compared to that of conventional vertical wells. This geometry is important both for hydraulic fracture propagation and the subsequent post-treatment well performance. Fracture tortuosity of arbitrarily oriented and horizontal wells is likely to cause large initiation pressures and reduction in the fracture widths. This paper presents a comprehensive study of the effects of important variables, including the principal stresses, wellbore orientation, and perforation configuration on fracture geometry. Initiation pressures. the contact between arbitrarily oriented wells and the fracture plane. and the near-well fracture geometry are determined and discussed. This study also shows that because of the near-well stress concentration the fracture width at the wellbore is always smaller than the maximum fracture width. This can have important consequences during hydraulic fracturing.

Introduction

Terzaghi studied vertical well fracture initiation about 70 years ago. That work resulted in the famous Terzaghi criterion, which is relatively simple and easy to use. The initiation of a fracture from an arbitrarily deviated well (in general, a well not aligned with one of the principal stresses), however, is much more complicated. Fracturing from such a well may result in multiple fracture initiations with an eventual link-up of these starter fractures into a dominant one. Such a fracture during its propagation is likely to turn and twist in the near-wellbore region.

Fracture tortuosity can lead to proppant bridging and premature screenouts. Even if brought to successful execution, tortuous fractures are likely to be choked with considerable reduction in the post-treatment production performance.

Yew et al. studied the deviated-well fracture initiation and demonstrated theoretically that fracture reorientation happens only in the near-wellbore region. The influence of the wellbore on stress distribution decreases rapidly with distance r (proportional to 1/r2). Abass et al. and Hallam et al. explored this phenomenon experimentally and showed that the creation of nonplanar fracture geometries such as multiple. T-shape. and reoriented fractures depend on the wellbore direction relative to the in-situ stress field. An optimum wellbore azimuth is necessary to avoid the creation of undesirable fracture geometry. Sousa attempted to solve this problem numerically using fracture mechanics principles.

In this paper, the following problems are addressed:

1. The effects of well orientation on fracture initiation. The study is based on stress analysis. Generalized type curves are developed to guide perforation design and provide information on optimal well orientation for fracturing.

2. Fracture tortuosity in the near-wellbore region. During propagation the fracture turns and adjusts toward the direction of minimum resistance. This path has a great impact on the near-well fracture geometry. A simple-to-use criterion is presented to predict the fracture orientation and width.

3. Single- and multiple-wing fractures.

P. 821

angle, arbitrarily, closure, complex reservoir, direction, fracture, fracture initiation, Horizontal, horizontal well, hydraulic fracturing, initiation, near-well fracture geometry, optimal, optimal initiation, orientation, perforation, reservoir description and dynamics, SPE, stress, Upstream Oil & Gas, well completion, wellbore

SPE Disciplines:

SPE Members *Now at U. of Tulsa

Abstract

Transient rate analysis is currently focused on infinite or circular reservoirs with concentric wells. Rate decline responses for a constant pressure well which is arbitrarily located in a regularly or an irregularly shaped reservoir or in a composite reservoir are not documented in the literature. This paper presents two new solution techniques for rate decline behaviors in such complex systems. For the composite model, the analytical Laplace solution is based upon placing a constant pressure well with an arbitrary location in a two-composite radially concentric domain. By varying the properties and the geometrics of the domains, the new model provides several new settings for transient rate analysis. The paper discusses the characteristic responses of such composite systems. In the case of an arbitrarily shaped drainage area, the external boundary is replaced by a group of line source boundary wells. The paper outlines the criteria for placing these wells to create the effects of the boundary. This semi-analytical method permits us to study rate declines in cases that cannot be studied analytically.

Introduction

Pressure transient and rate transient well testing are used as tools to identify the characteristics and predict the behavior of reservoir systems. The two kinds of test yield the same information about the reservoirs, However, these two kinds of tests differ in some practical and mathematical aspects. From a mathematical point of view, some mathematical techniques can be easily applied to the constant flow rate condition, but not to the constant pressure condition. Decline curve analysis is used to predict future production. Rate declines are classified as either empirical or analytical.

Arps [1945] describes three kinds of empirical decline curves for boundary-dominated flow periods: exponential, hyperbolic and harmonic declines. Gentry [1972] manipulates the decline equations to prepare decline curves. The decline curves simplify the extrapolation of future productions for Arps decline curves. Some analytical solutions for transient rate decline are available. van Everdingen and Hurst [1949] and Carslaw and Jaeger [1960) present mathematical solutions. Earlougher [1977] discusses constant pressure testing and provides the equations to obtain the permeability and skin factor from production data. Fetkovich [1980] develops decline curves by combining analytical constant-pressure infinite and finite reservoir solutions. He applies log-log type curve analysis for both the transient and the late time decline flow periods. Uraiet and Raghavan [1980] present a study of transient rate behavior of a reservoir with a constant wellbore pressure condition. They determine that the semi-log analysis method for constant rate testing can be applied to transient rate if the reciprocal rate is used. Ehlig-Economides and Ramey [1981] provide the analytical solution for the exponential depletion state.

Analytical and numerical models of heterogeneous reservoir system are found in some papers.

P. 243^

active well, arbitrarily, Bessel function, boundary, boundary well, center, curve, Drillstem Testing, drillstem/well testing, effect, equation, formation evaluation, image well, irregular reservoir, region, reservoir description and dynamics, Response, solution, system, Upstream Oil & Gas, well, wellbore

SPE Disciplines: Reservoir Description and Dynamics > Formation Evaluation & Management > Drillstem/well testing (1.00)

No preview is available for this paper.

approximation, arbitrarily, body, demagnetization, demagnetization effect, field, Field Experiment, flow in porous media, Fluid Dynamics, integral equation, magnetic modeling, magnetostatic problem, pohanka, rectangular prism, Remanent Magnetization, Reservoir Characterization, reservoir description and dynamics, total magnetic field, vertical gradient

SPE Disciplines:

No preview is available for this paper.

analysis, approach, arbitrarily, Artificial Intelligence, Computation, dynamic programming traveltime, field, grid, migration, migration output, optimization problem, pre-stack depth migration, pre-stack depth migration velocity analysis, Prestack Depth Migration, PSDM velocity analysis, Reservoir Characterization, reservoir description and dynamics, Schneider, seismic processing and interpretation, traveltime, traveltime computation, Upstream Oil & Gas

SPE Disciplines: Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)

Technology:

An original applied study has been developed, concerning the analysis and the prediction of the hydrodynamic forces Which act upon arbitrarily oscillating bodies in the sea. The Morison formulations have been applied also for the case of constant drag and mass coeffiCIents, when the wake veloc1tles which are produced by the body motIons in all the past histories are opportunely corrected; moreover the wake velocities have been here computed also on the basis of the unsteady turbulent theory, which is available from the existing literature. The predicted results have been compared with the experimental ones, coming from a deal of lab pendulum tests. The said tests have been performed both on single and on coupled cylinders, with particular care for the overall configuration cases and possibilities. Starting from the 1st case of square cylinders, the study has been after- wards generalized to the case of circular cylinders, more adequate - in many cases - to represent and to model the spatial and the physical reality.

INTRODUCTION

The design of the majority of the offshore structures for offshore petroleum drilling and product1on operations requ1res a careful prediction of the hydrodynamic forces Which act on their components. Many of them are, in most cases, members having circular and other cross sections, with their submerged parts frequently close to the free surface of the water. In Chung (1976) as far as the floating structures are concerned constant values of the added masses have been considered, and also zero wave damping values (obtained for an infinite fluid). Among the first Chung (1977) published real comparisons of experimental added masses and wave damping coefficients with theoretical coefficients computed by the Frank''s method, showing that agreements are much better for circular cross sections, and better for heaving than for swaying motions.

arbitrarily, body, body angle, Body System, case, coefficient, drag, effect, Fourier, mass, Matsumoto, Morison, Morison formula, oscillation, study, system, theory, wake

Thank you!