Water Alternating Gas

Keywords production decline, economic decline, infill drilling, bypassed oil, attic/cellar oil, production potential, coiled tubing, formation damage, cross-flow, side-track, enhanced oil recovery (EOR), steam injection, in-situ combustion, water alternating gas (WAG), debottlenecking, produced water treatment, well intervention, intermittent production, satellite development, host facility, extended reach development, extended reach drilling. 

Alkali/polymer flooding Alkali/surfactant/polymer flooding Alkaline-assisted thermal oil recovery Alkaline steamflooding Polymer-assisted surfactant flooding Water-alternating gas technology... 

The oil production from thin under-gas cap zones with an active aquifer is not efficient because of the rapid breakthrough of gas or water. The water-alternating gas technology based on the injection of water solution with oil-and water-soluble polymers seems to be promising to stimulate such wells. For heavy oils, this technology can be considered as an alternative to thermal-enhanced oil recovery [1673]. 

Miscible water-alternating-gas (WAG) process. Injection alternates between gas (usually natural gas or C02) and water the miscible gas and oil form one phase. The WAG cycles improve sweep efficiency by increasing viscosity of the combined flood front (Figure 12). 

The Cardium Formation of the Pembina Field is located approximately 115 kilometres southwest of Edmonton, Alberta, Canada. The Pembina Field was discovered in 1953 and put on primary production in 1955. It was converted to a water flood starting in 1958. In March, 2005, a C02 monitoring pilot was initiated by Penn West Energy Trust at their C02-EOR operations within the field. C02 was injected into two wells and water into several wells around the immediate pilot area. Early in 2007, the pilot was converted to a WAG (Water Alternating Gas) EOR scheme, where on an approximately monthly basis, the injection of water and C02 are switched to the other well. 

At the present time, a number of gelling systems exist which can be used to divert the flow of driving fluids to less permeable zones to recover more petroleum from subterranean formations. Several field treatments with polyacrylamide-aluminum citrate, polyacylamlde-Cr(lIl), lignosulfonateCr(lIl), xanthan gum-Cr(lIl), and phenolic-formaldehyde gelling systems have been economically successful. An in-situ polymerization technique has also been successful in diversion of driving fluids In a CO2 water alternating-gas operation. 

An ethoxylated alkyl sulfate with small amounts of amide stabilizers was used at concentrations (in the aqueous phase) of 0.5, 1.0, and 1.5%. The air-to-aqueous phase ratio (at reservoir pressure) was 10 1. Two types of tests were performed (1) alternate injections of surfactant solution and air, as in WAG (water alternating with gas) cycles and (2) simultaneous injections of air and surfactant solution, using the foam generator. Diagnostic chemical tracer injections were used before and after the tests. 

The electrochemical reactions proceed in ethanol-water or methanol-water mixtures. Alternatively, gas diffusion electrodes can be used. 

The manner of injection of the C02 is often at question. When no mobility-control additive is used, the choice is usually between continuous C02 injection and the so-called WAG (water alternated with gas) method. Continuous C02 injection method is generally used only when the reservoir is very tight or water-sensitive, so that water could be injected only at an uneconomically low rate. WAG was originally suggested by Caudle and... 

Fig. 10 in Figure 201 shows an apparatus for measurement of the gas (CO2) released when minium (red-lead or litharge, PbjO ) mixed with charcoal is heated in a furnace. Glass retorts were attacked by this chemical mixture, so Lavoisier fabricated an iron retort (Fig. 12). The tall inverted hell jar nNoo sits in a wooden or iron trough filled with water. A siphon inserted at n raises the water to YY. Alternatively, hand-pump P can connected using siphon EBCD (Fig. 11) and used to raise the column fairly high. The top of the water in jar nNoo is coated with a thin layer of oil. This is another way to collect a water-soluhle gas such as CO2 rather than by using mercury. To the right in Fig. 10 we see an apparatus for transfer of the gas collected in jar N to glass bottle Q. This important experiment demonstrated the release of an aerial fluid upon heating red-lead.

The mechanisms of dolomitisation are not well understood [2.3, 2.4], but undoubtedly involve passage of sea water through the pores of the limestone over long periods. The dissolved magnesium is able to replace alternate calcium ions in the crystal lattice, because dolomite is a little more stable than calcite. Moreover, as the crystal density of dolomite is about 10 % higher than that of calcite, dolom-itization is accompanied by an increase of porosity. This facilitates further dolomitisation. It also raises the capacity of a deposit to act as a reservoir for oil, water, or gas. 

FIGURE 12.5 Various base-pairing alternatives. GA is unlikely, because the 2-NH2 of G cannot form one of its H bonds even water is sterically excluded. U C may be possible, even though the two C=0 are juxtaposed. Two U U arrangements are feasible. G U and 1 U are both possible and somewhat similar. The purine pair I A is also possible. (Adapted from Crick, F. H. C., 1966. Codon-anticodon pairing The wobble hypothesis. of Molecular Biology 19, 548-555.)... 

The role of the shoulders as water and gas vents remains as the most important mechanism governing the emissions from a road where residues are used as an alternative unbound material... 

Many metals oxidize in contact with the air or moisture. For reactive metals, this reaction may be particularly violent and evolve high heat. When in contact with water, hydrogen gas is liberated which will ignite if temperatures are sufficiently high. Alternatively other combustibles may be similarly ig-... 

All of these hydrocarbon-miscible processes can recover oil, but there are many difficulties. Mobility control is a very serious problem, although techniques such as alternate water and gas injection (WAG) can be used to reduce the mobility of the lighter, driving fluids (113). In the United States, the intermediate hydrocarbons as well as methane are in short supply and are valuable as fuel or chemical feedstocks. Therefore, much attention in the United States is now focused on materials such as CO2 or other inert gases which have no fuel value but which can provide some miscible displacement under certain conditions. In parts of the world where light hydrocarbons and methane are available, the hydrocarbon-miscible process and various modes of gas injection should increase oil recovery for many years. 

The energehc electrons, which constitute the arc, decompose some oxygen molecules to atoms and these react with to form Oy A gas mixture with 15% ozone may be obtained. Ozone is utilized as an oxidation agent in the organic chemical industry and for the disinfection of water. Chlorine gas was earlier used for the bleaching of paper pulp, but more ecofriendly alternatives have been sought the main substitute is hydrogen peroxide H Oj, but ozone has also been tested. 

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