No abstract

Johnson Jr., L.A., SPE-AIME, U.S. DOE, Laramie Energy Technology Center Fahy, L.J., U.S. DOE, Laramie Energy Technology Center Romanowski, L.J., U.S. DOE, Laramie Energy Technology Center Barbour, R.V., U.S. DOE, Laramie Energy Technology Center Thomas, K.P., U.S. DOE, Laramie Energy Technology Center This paper presents the description and analysis of a combination reverse and forward combustion experiment for the production of oil from a Utah tar sand. The experiment produced 25% of the OOIP from a 13-ft thick tar sand zone containing at 14 deg. API, million-plus cp oil. The results were encouraging for future tar sand production. Introduction U.S. tar sand resources contain an estimated 30 billion bbl (4.7 Gm) of oil in place in about 550 occurrences in 22 states. Over 90% of the known resources are in six large deposits in Utah, each containing from 1 to 16 billion bbl (0.15 to 2.5 Gm) of oil. Four major tar sand deposits in Alberta, Canada, contain some 900 billion bbl (143 Gm) of oil, and deposits in Venezuela and Colombia contain an estimated 1 to 1.8 trillion bbl (0.15 to 0.28 Tm t). The first U.S. DOE tar sand field experiment (LERC TS-1C) was conducted in Utah's Northwest Asphalt Ridge deposit in late 1975. LERC TS-1C accomplished its two primary goals:to demonstrate the feasibility of applying a reverse combustion process to a heterogeneous tar sand reservoir with a process to a heterogeneous tar sand reservoir with a high average oil saturation andto provide the Laramie Energy Technology Center (LETC) research personnel with valuable experience in application of personnel with valuable experience in application of the combustion process and operation of its related equipment. Results of LERC TS-1C and supporting research are reported in several publications. LERC TS-1C provided encouragement for a second field experiment (LERC TS-2C) designed to use reverse combustion as a preparatory phase for forward combustion. LERC TS-2C tested the technical feasibility of the application of a combination thermal recovery process - reverse and forward combustion - for the process - reverse and forward combustion - for the in-situ extraction of oil from tar sands. The reverse combustion (preparatory) phase improved the natural reservoir conditions for application of the forward combustion (production) phase. However, the fire front moved through the pattern in a series of reverse and forward combustion phases (echoing combustion) during the experiment. The experiment was ignited in late Aug. 1977 and completed in Feb. 1978. More than 25% of the oil in place was produced in 183 days from a 13-ft (4-m) thick test produced in 183 days from a 13-ft (4-m) thick test zone at a depth of 350 ft (107 m) within a 40 × 120 ft (12 × 36 m) nine-well line drive pattern. Experimental Plan The design of LERC TS-2C was based on laboratory combustion experiments and LERC TS-1C. Laboratory studies provided the parameters of optimum air flux, combustion front velocities, flame front temperatures, and theoretical oil recovery. Three main observations from LERC TS-1C were (1) the test zone had a preferential direction of permeability along the strike line, (2) the reverse permeability along the strike line, (2) the reverse combustion front tended to travel through the most permeable portion of the test zone with little vertical permeable portion of the test zone with little vertical spreading, and (3) the produced fluids contained a large portion of heavy viscous oil and solids, which caused conventional oil production equipment to fail. JPT P. 295

Johnson Jr., Lyle A., SPE, Laramie Energy Technology Center, U.S.DOE Fahy, L. John, SPE, Laramie Energy Technology Center, U.S.DOE Romanowski Jr., Leo J., SPE, Laramie Energy Technology Center, U.S.DOE Thomas, Kenneth P., Laramie Energy Technology Center, U.S.DOE Hutchinson, Harold L., SPE, U. of Wyoming Summary The first U.S. DOE Laramie Energy Technology Center (LETC) steamflood experiment in a Utah tar sand, LETC TS-1S was conducted in the Northwest Asphalt Ridge deposit near Vernal, UT. Steam was injected into the center well of two concentric inverted five-spot patterns. The zone chosen for the experiment was a sandstone 45 ft (14 m) thick in the Rimrock member of the Mesaverde formation. The pattern area was 0.25 acres (1012 M2) and contained a 13 degrees API (979 kg/m) bitumen with a viscosity greater than 10 Cp (10 Pa.s) at reservoir conditions. The average oil saturation was 78.9% PV. During 160 days of operation, 65,700 bbl (10.4 × 10 m) of water-equivalent steam were injected at 360 to 530 psig (2.5 to 3.7 MPa) and 180 to 650 B/D (29 to 103 m /d). Total production during the test amounted to 1,150 bbl (183 m) of oil and 6,250 bbl (994 M) of water. Introduction LETC has been working toward development of U.S. tar sands since 1973. To date LETC has conducted several laboratory studies and three field tests of the technical feasibility of in-situ thermal processing of Utah tar sand. The first two field tests, LERC TS-1C and LERC TS-2C, were conducted in 1975 and 1977-78 to test the technical feasibility of the reverse combustion process and a combination reverse/forward combustion process, respectively. Results of these laboratory and field tests have been reported in several publications. The third field test (LETC TS-1S conducted during 1980) tested the technical feasibility of steamflooding a tar sand formation; it is the basis for this paper. LETC TS-1S steamflood began April 23, 1980, and ended Sept 29, 1980. During 160 days of operation, 65,700 bbl (10.4 × 10 m) of water-equivalent steam were injected into the 45-ft (14-m) thick, 500-ft (152-m) deep tar sand zone. During the operational period, 1,150 bbl (183 m) of oil and 6,250 bbl (994 m) of water were produced. Experimental Plan The objectives of LETC's first steam in-situ recovery experiment were (1) to determine the technical and economic feasibility of using a steamflood as an in-situ recovery technique in a Utah tar sand deposit, (2) to evaluate an injection well completion scheme with a high-temperature packer, (3) to evaluate several types of downhole completion schemes for the production wells, and (4) to determine recycle and fuel use possibilities for produced water and oil. Design of LETC TS-1S was based on core analysis, data from a small two-well steam injection test, laboratory studies, a literature survey, and computer modeling. The pattern was two concentric inverted five-spot patterns (Fig. 1). The outer four producers (Wells 3P1 through 3P4) were on the perimeter of 0.25 acres (1012 m), while the inner four producers (Wells 3PS through 3P8) bounded 0.1 acres (405 m2). Monitor Wells 3M1 through 3M4 were spaced at approximately half the spacing of the 0.1-acre (405-m2) pattern. On the basis of preliminary computer modeling results, the 0.25-acre (1012-m2) and 0.1-acre (405-m2) areas represented the best estimates of the maximum and minimum areal sweeps expected during the desired 120-day test period. Test Zone Description The major source of tar sand on Northwest Asphalt Ridge is the Rimrock sandstone member of the Cretaceous Mesaverde formation. The Rimrock is a highly saturated, semiconsolidated, fine-grained sand- stone interrupted by many low-saturated siltstone or shale intervals that vary in thickness from less than 1 in. (2.54 cm) to more than 10 ft (3 m). JPT P. 1119^

One type of spheroidal cast iron, with additions of 0.51% Cu and 0.72% Ni, was subjected to precipitation hardening. Assuming that the greatest increase in hardness after the shortest time of ageing is facilitated by chemical homogenisation and fragmentation of cast iron grain matrix, precipitation hardening after pre-normalisation was executed. Hardness (HB), microhardness (HV), qualitative and quantitative metalographic (LM, SEM) and X-ray structural (XRD) tests were performed. The acquired result of 13.2% increase in hardness after ca. 5-hour ageing of pre-normalised cast iron confirmed the assumption.