1,598,504 research outputs found
Gravitoelectromagnetism in metric f(R) and Brans–Dicke theories with a potential
No full textA Gravitoelectromagnetism formalism in the context of metric f(R) theory is presented and the analogue Lorentz force law is derived. Some interesting results such as the dependence of the deviation from General Relativity (GR) on the absolute value of the scalar potential are found, it is also found that the f(R) effects are only relevant at a shorter distance or when the distance is much less than the compton wavelength, and that the effects are attractive in nature. An investigation of gravitational time delay in the context of metric f(R) is also presented showing that the Ricci scalar alone is responsible for the time delay effect which seems to suggest that the extra scalar degree of freedom associated to f(R) does not provide any modification. Also, to generalise our results, the Lorentz force law and gravitational time delay in the case of Brans-Dicke theories with a potential are derived; it is shown that the results are consistent with those obtained in the case of metric f(R) and GR in the appropriate limits
The gyroscopic frequency of metric f(R) and generalised Brans–Dicke theories: constraints from Gravity Probe–B
No full textWe confront the predicted gyroscopic precession (in particular the geodetic precession) from metric f (R) theory with the data provided by the mission, Gravity Probe-B. We find the constraint, vertical bar a(2)vertical bar < 1.33 x 10(12) m(2), where a(2) is the coefficient assessing the strength of the lowest order correction to the Einstein-Hilbert action for a metric f (R) theory with f analytic. This constraint improves over astrophysical bounds provided by massive black holes and planetary precession which are vertical bar a(2)vertical bar greater than or similar to 10(17) m(2) and vertical bar a(2)vertical bar less than or similar to 1.2 x 10(18) m(2) respectively and it is complementary to the stringent ones provided by lab based experiments, like the Eot-Wash experiment. We also investigate the modification of our result for gyroscopic precession if the oblateness of Earth is taken into account by considering the quadrupole moment of Earth. Finally, we provide a generalisation of our result for the gyroscopic precession in the context of Brans-Dicke theories with a potential (recovering the previously derived results in the appropriate limits)
DASS Well- A New Concept of Multiple Zone Well Completion
No full textAbstract
Over the years, several techniques for multiple zone well completions were evolved in oil industry but due to some or other reasons the popularity of multiple zone well completions lost. Earlier attempts for multiple zone completions were to use multiple tubing or commingling large number reservoirs. Now a new concept of well completion is available in which all the advantages of multiple tubing completions and commingle production can be retained with a single tubing well completions.
The name of the concept well is DASS well. DASS well stands for Dynamically Activated Super Solution wells. The well architecture is radically different from existing well completions. The reservoir fluid enters the well bore through a production chamber. Production chamber is one device which is set over perforations. Multiple production chambers can be installed in a well depending upon the number of zones available for production. A multiphase flow meter and fluid flow control valve are fitted in the production chamber which is operated from surface control panel. The well fluid is flowed from production chamber through control valve to the well bore. The well depth depends upon the expected fluid production rate. A down hole pump is installed to pump the liquid through tubing and gas is produced through annulus in such a way that surface separation minimized/eliminated.
In this paper, the author introduces "DASS well" - the new concept of multiple zone well completion with detailed description and diagram with its advantages and disadvantages.
Deepwater development demands a simple and cheap well completion technology which can help in efficient production, handling, storage and transportation of oil and gas in addition enhancing oil production through advance processes. DASS WELL-the new concept for multiple zone well completion can prove helpful in this direction.</jats:p
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