This paper describes the axial, torsional, and transient buckling vibratory models developed for the selection of optimum core rod size. The axial and torsional vibratory core rod simulator (VCRS) models are coupled by way of a transient buckling wave which propagates over the length of the core rod. This paper reports the frequencies and magnitudes of the stresses in the 101 core rod now in use. In addition, four core bit vibratory forcing functions for thrust and torque were developed. The thrust and torque frequencies and magnitudes for the bit forcing functions were extracted from full-size laboratory core bit tests with fast Fourier transforms. The natural frequencies of the core rod were determined with closed-form solution models and were confirmed with a finite element model. Finally, a selection of core rod sizes were modeled to determine the best size to minimize damaging stress which stems from vibration.

Summary A finite-element program, ANS YS, was used to determine the change in physical dimensions of oilfield tubulars and the growth of stresses in their walls as these tubulars were run and landed into a drillhole. Ovalities and axial and tangential stresses modeled with a finite-element method (FEM) are presented in easy-to-use charts for 7- and 95/8-in.-OD API casing. Axial bending stresses with the FEM are are compared with those under Lubinski's bending equation and the classic beam-bending equation.

An oblique circular arc representation for wellbore trajecories, a geometric analysis termed the sectional method, is presented. This approach permits projected line segments to be functions of the dogleg angle and to be related to usually measured displacements between survey stations. The advantages of this analysis are: a solution for the dogleg angle and a method of survey interpretation, the sectional method; a procedure for exact interpolation of true vertical depth, azimuth, and inclination between survey stations; a basis of solution for a computer program which provides course correction information during a turn to a target. The program provides a solution summary for a course correction from various survey stations in a well to any planned target. As a result, an optimum course correction or "minimum plugback depth" can be quickly determined. Once the desired kickoff point is selected, the program provides an exact solution of true vertical depth, azimuth, inclination, and toolface angle for every 100 of correction course length. The latter result provides a dramatic improvement in existing technology because all measurements used to control the correction run are now based on a center of turn rather than the arbitrary reference used in the typical ouija board solution; and because the solution is exact, such variables as effective toolface angle can better be evaluated and precisely corrected resulting in the smoothest possible turn with minimum doglegs.

The multimode method of Cheng and Mitchell [1981] is used to study the attenuation properties of the crust throughout the Barents shelf. The sensitivity of the spectra to various source factors and to propagation factors which might characterize a shelf region are thoroughly studied. For plane-layered models, the method is very sensitive to Qβ in the upper crust and to Qβ of sedimentary layers if those layers are thick and highly attenuating. It is far less sensitive to Qβ in the lower crust and to Qα. The spectra, for shallow strike slip earthquakes, are very insensitive to changes in strike, slip, and dip angles of the fault throughout the entire period range of interest but are very sensitive to variations in focal depth except in the long-period range of the fundamental mode and the short-period range of the higher modes. The fundamental mode, but not the higher mode, spectra for one path across the Barents shelf are, apparently, distorted at short periods by lateral heterogeneities along the travel path. Simple two-layer, trial-and-error inversions yield a model of the Barents shelf with an upper crustal Qβ value of about 80. Three-layer inversions with a sedimentary layer, however, yield an upper crustal Qβ of about 250, if the sediments are 1 km thick and are characterized by Qβ values of 40. Shear velocity models for the Barents shelf show variations between about 3.0 and 3.6 km/s in the upper crust along different paths. The lower crust shows smaller regional differences, but velocities vary between 3.5 and 4.0 km/s through the depth range 25–35 km. The variation of shear velocities in the upper mantle may correlate with those of the upper crust and vary regionally between about 4.3 and 4.8 km/s.

Mixtures of cyanide and thiocyanate in hydrometallurgical effluents heavily clouded with particulates are titrated quickly and successfully with silver nitrate solution by using a potentiometric automatic titrator fitted with a silver working electrode and a glass reference electrode. When thiocyanate is to be determined, cyanide is masked with formalin. Titrations over a wide range of concentration and ratio of the two species require minimum pre-treatment of the samples and give sharp end-points and good replication.

The method of predictive deconvolution is described and applied to seismograms from the 1963 Lake Superior experiment. The process is successful in removing shot-generated reverberations and sometimes reveals seismic phases which are not easily identifiable on the original seismograms.

Research Article| September 01, 1970 Interpretation of a Crustal Section across Oklahoma B. J MITCHELL; B. J MITCHELL University of Texas at Dallas, P. O. Box 30365, Dallas, Texas 75230 Search for other works by this author on: GSW Google Scholar M LANDISMAN M LANDISMAN University of Texas at Dallas, P. O. Box 30365, Dallas, Texas 75230 Search for other works by this author on: GSW Google Scholar Author and Article Information B. J MITCHELL University of Texas at Dallas, P. O. Box 30365, Dallas, Texas 75230 M LANDISMAN University of Texas at Dallas, P. O. Box 30365, Dallas, Texas 75230 Publisher: Geological Society of America Received: 28 Jul 1969 Revision Received: 14 Apr 1970 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1970, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1970) 81 (9): 2647–2656. https://doi.org/10.1130/0016-7606(1970)81[2647:IOACSA]2.0.CO;2 Article history Received: 28 Jul 1969 Revision Received: 14 Apr 1970 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation B. J MITCHELL, M LANDISMAN; Interpretation of a Crustal Section across Oklahoma. GSA Bulletin 1970;; 81 (9): 2647–2656. doi: https://doi.org/10.1130/0016-7606(1970)81[2647:IOACSA]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A new interpretation for a complex crystal section across Oklahoma is derived from the unified study of a wide variety of observations. The set of data includes refraction observations from a reversed profile, reflection data, gravity measurements, well log information and knowledge of the near-surface geology.The model is divided into three parts according to the elevation of the basement surface and the properties of the overlying sediments. The upper portion of the crust is characterized by a major low velocity zone that has participated in vertical movements at major faults crossing the profile.Four continuous interfaces underlie this low velocity zone, the deepest being the crust-mantle boundary at a depth of 46 km. The continuity of these surfaces and the vertical displacements above the low velocity region imply that in this area major tectonic movements are restricted to the portion of the crust which lies above the base of the velocity reversal. Crustal mobility in this area may possibly be related to the presence of this low velocity zone. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.