Antimonic acid cannot be dehydrated by heating in air to give products of constant and reproducible weight without simultaneous reduction of some of the SbV to Sb"'. Neither anhydrous Sb20, nor the hydroxy oxide Sb3060H postulated by Dihlstrom and Westgren can be obtained by this method. Two well-defined products of the dehydration/decomposition are Sb204.,,,,, = Sb6013, which forms between 650 and 850", and p-Sb204. The latter, and not Sb203, results on heating Sb6013 to 935". Sb6OI3 has a cubic structure of the defect pyrochlore type, a, = 10.303(1) A, x(02) = 0.4304(14). Combined evidence from X-ray diffractometry, density determination, and Mossbauer spectroscopy leads to Sb3+SbS+,060,~, as the most probable structural formula.The Mossbauer parameters of P-Sb204 are closely similar to those reported for a-Sb204, but the isomer shifts (relative to InSb at 77 OK) for Sbv in antimonic acid and Sb6013 are significantly larger than those in a-and p-Sb,04.L'acide antimonique ne peut &tre deshydrate par chauffage a I'air pour donner des produits de poids con-
THAI-"Toe-to-Heel" Air Injection, is a new EOR process, which integrates advanced technology and horizontal well concepts, to achieve a potentially very high recovery of heavy oil. It can also realize very substantial in situ upgrading by thermal cracking, producing upgraded oil to the surface. The process operates in a gravity stabilized manner by restricting drainage to a narrow mobile zone. This causes the flow of mobilized fluids to enter directly into the exposed section of a horizontal production well. The process can be operated on primary production, asnew technology, as a follow-up to existing technologies, or asa co-process where the advantages of high thermal efficiency are equired. This is achieved by concentrating the energy required for oil mobilization, recovery and thermal upgrading in the reservoir. Combined with clean technology design, THAI offerspathway, to future economic success for the heavy oil industry. Three-dimensional, semi-scaled experimental tests on light "Forties Mix" oil (30.7 °CDATA[API), Clair, West of Shetlands medium heavy oil (20.8 °CDATA[API), and heavy Wolf Lake oil (10.95 °CDATA[API) show that a well-controlled, narrow mobile oil zone is created just ahead of the combustion front. The width of this narrow zone depends on the characteristics of the heavy oil at reservoir conditions and the degree to which the very high viscosity of the cold oil seals the horizontal producer well. Well sealing can be augmented by a novel sleeve-back technique, which allows perforated downstream sections of the well to be shut-in. The application of this technique enabled the light oil test to mimic the operation of a heavy oil reservoir using THAI. Very high oil recoveries were achieved in the tests, up to 85﹪ OOIP. During wet in situ combustion (ISC), Wolf Lake oil was upgraded to 20 °CDATA[API, achieving a reduction in the cold oil viscosity from 100,000 mPas to around 50 mPas. Introduction Horizontal and multi-lateral wells are being introduced in ever increasing numbers to achieve further gains in reservoir productivity. Two hundred horizontal wells were drilled a decade ago. Now, one company has reported drilling more than 2,100 horizontalwells in North America(1). Advances have also been achieved in the depths drilled, reaching 8,761m(2) and lengths now reaching up to 11 km. Multi-lateral wells, with four or more side-tracks, are not uncommon and offer further optimization gains. Moreover, this technology will accommodate reservoir faults and problems of structural geology as regular design factors so that strategic placement of the well path is achieved. More recently, a new technique to control gas and water production rates by varying the fluid entry points has been successfully tested(3). The most important advantage of horizontal wells is the increase in the reservoir contact area compared to a vertical well. Horizontal wells have created new possibilities for the implementation of advanced IOR methods, especially in thermal recovery.
TX 75083-3836, U.S.A., fax 01-972-952-9435. Abstract
fax 01-972-952-9435. AbstractThe expansion of heavy oil and bitumens production is limited by the lack of advanced upgrading facilities and technology. Surface processing, mainly by delayed coking and some hydroprocessing, is very capital intensive. This cost can be more than that for the reservoir engineering facilities. The THAI process achieves substantial upgrading of heavy crude oil directly in the reservoir, via thermal cracking and associated reaction transformations.It captures the underground upgrading because the horizontal producer well process operates via a 'short-distance displacement mechanism', similar to that which occurs in the SAGD process.
Crystals of a new lanthanide orthosilicate, Yb3(Si04)2Cl, were prepared by vapor transport in a chlorine atmosphere. A complete single-crystal structural analysis showed that the crystal class is orthorhombic, a = 6.731 (2), b = 17.556 (8), c = 6.129 (2) A.With 4 formula units in space group Pnma the calculated density is 6.77 g cm'3. A full-matrix leastsquares structure factor refinement effected with the 460 observed reflections collected by the -scan procedure and anisotropic thermal parameters for the Yb atoms gave R = 3.0% and Rw = 2.2%. The ytterbium atoms are in two sites and are eight-coordinated as Yb06Cl2 square antiprisms and as Yb07Cl dodecahedra that can also be described as Yb-(Si04)5Cl octahedra. The presence of the chlorine atoms causes some long Yb-0 bonds. ri$-Tetracarbonyldiphosphinechromium(0) far side of the Yb(l)-(Si04)4 plane. The shortest 0(2)-Cl distance is 3.165 A. Only the 0(5) oxygen atoms are completely separated from the chlorines; one of these gives the shortest Yb-0 bond: Yb(l)-0(1)5,2.19 A.
fax 01-972-952-9435. AbstractThe expansion of heavy oil and bitumens production is limited by the lack of advanced upgrading facilities and technology. Surface processing, mainly by delayed coking and some hydroprocessing, is very capital intensive. This cost can be more than that for the reservoir engineering facilities. The THAI process achieves substantial upgrading of heavy crude oil directly in the reservoir, via thermal cracking and associated reaction transformations.It captures the underground upgrading because the horizontal producer well process operates via a 'short-distance displacement mechanism', similar to that which occurs in the SAGD process.
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