The binding energy of a polaron confined in the quantum well of GaAs/Ga& "Al"As double heterostructures is calculated as a function of the magnetic field applied in the direction of growth. We have also calculated the oscillator strength of electron-phonon interaction for transitions from various excited states to the ground state of the polaron. Every type of optical-phonon mode that can exist in such structures within the continuum model is considered separately. It is found that the magnetic field 0 greatly enhances the interface-phonon part of the polaron effect. For quantum wells of widths 150 A or smaller, the interface modes dominate all polaronic phenomena we have encountered when B~1 T. For 0 quantum wells of widths up to 100 A, contributions from confined bulk phonon modes are almost negligible in magnetic fields B~1 T.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractMost of the fields located in south of Oman are mature, sub-hydrostatic, producing viscous, and sandy oil. This has raised the need to deploy different artificial lifting mechanisms. Progressive Cavity Pump (PCP) is one of the lifting methods in use and unlike other lifting methods it has proved its capability to produce viscous oil and tolerates more with sand production. Besides, PCPs can be run deeper in deviated wells for better drawdown. Currently in South of Oman we have more than 400 PCP wells and by the end of 2013 the PCP population is expected to reach 1000 units.South of Oman fields are characterised by being geologically complex and extremely heterogeneous due to existence of faults and fractures. Water flooding project was started to enhance oil recovery in those fields. To evaluate the success of water flood performance the wells require well intervention work such as coil tubing and wireline for well bore cleaning, well logging, selective water shut-off, re-perforation, and well stimulation. As completions needed to be removed, therefore in the past work could never be performed concurrently with production. The inability to evaluate water flood performance caused remedial work to become ineffective. The need for surveillance and an intervention string for the PCP drive completions were identified. This paper presents the ideas developed to make concurrent production and well-intervention work with PCP completions is possible without interrupting production, including well kill. In this process, we looked at all aspects of PCP completions (Surface/ Subsurface) from running the completion to its maintenance. The design needed to overcome serious engineering challenges such as extremely tight surface tolerances with restricted geometries. The new design consists of an eccentric PCP drive head at surface, a downhole dual receptacle style torque anchor and housing for two parallel tubing strings. The innovative design was done locally by a multi-disciplinary team of PDO and local service companies. There was no appropriate solution available in the international market. The technology has been proven reliable on 10 wells and is now an integral part of a standard well design with 58 wells in planning as part of the Program Build for the year 2009.