Sandstone injection

Wettabihty is defined as the tendency of one fluid to spread on or adhere to a soHd surface (rock) in the presence of other immiscible fluids (5). As many as 50% of all sandstone reservoirs and 80% of all carbonate reservoirs are oil-wet (10). Strongly water-wet reservoirs are quite rare (11). Rock wettabihty can affect fluid injection rates, flow patterns of fluids within the reservoir, and oil displacement efficiency (11). Rock wettabihty can strongly affect its relative permeabihty to water and oil (5,12). When rock is water-wet, water occupies most of the small flow channels and is in contact with most of the rock surfaces as a film. Cmde oil does the same in oil-wet rock. Alteration of rock wettabihty by adsorption of polar materials, such as surfactants and corrosion inhibitors, or by the deposition of polar cmde oil components (13), can strongly alter the behavior of the rock (12). 

FIG. 25-78 Schematic diagram of an industrial-waste injection well completed in competent sandstone. (From Vreeman, H M, Standard Handbook of Hazardous Waste Treatment and Disposal, McGraw-Hill, 1988.)... 

T. Austad, S. Ekrann, I. Fjelde, and K. Taugbol. Chemical flooding of oil reservoirs Pt 9 Dynamic adsorption of surfactant onto sandstone cores from injection water with and without polymer present. Colloids Surfaces, Sect A, 127(l-3) 69-82, 1997. 

Filter. A filter is used in some cases when coagulation and sedimentation do not completely separate the solids from the liquid waste in areas where sand and sandstone formations are susceptible to plugging. Filters with a series of metal screens coated with diatomaceous earth or cartridge filters are typically used.27 Where limestone formations with high solution porosity are used for injection, filtration is usually not required. 

Well head pressures increased when injection was stopped at Well No. 1 for more than 24 h, apparently caused by a combination of precipitation reactions and backflow of sand. Injecting a slug of brine after every period of interrupted flow solved this problem. Movement of the main organic constituents (n-hexylamine, butanal, butanol, and phenol) was assumed to be slowed by adsorption. This conclusion was based on laboratory adsorption experiments by involving a different geologic formation (Cottage Grove sandstone) no direct observations were made of the injected waste. For current hazardous waste injection wells in Texas, the reader can refer to Texas Environmental Profiles web site for on-line resources for the State of Texas.185... 

Earlier corrosion inhibitors limited the maximum strength of the acid to 15% by weight. Improved corrosion inhibitors (see below) have made the use of higher acid concentrations, such as 28% HCl more common. More dilute solutions may initially be injected in sandstone acidizing to reduce the formation of insoluble sodium and potassium fluorosilicates by displacing saline formation water before injection of hydrochloric acid. 

Another series of experiments used sandstone cores previously injected with starved bacteria to investigate the ability of the bacteria to grow within rock cores when given a suitable nutrient Berea sandstone cores of 200 and 400 millidarcy (md) permeabilities were used as they were considered to be more representative of reservoir conditions than the glass bead cores. The sandstone cores were injected with 300 to 450 pore volumes of 10 /ml starved bacteria until the cores contained an even distribution of bacteria (Fig. 3A B) and the core permeabilities were between 13% and 18%. SCM nutrient was injected through the cores (Fig. 3C) until the core permeability fell to 0.1%, this required 360 pore volumes of SCM. 

Compositional changes in the formation water sampled from the Waarre C sandstone at the Otway Project pilot site provide information on the physical and chemical processes taking place during the injection and migration of C02. By... 

Geologic sequestration is already being done in the North Sea. The field produces gas that is heavily contaminated with natural carbon dioxide. Before shipping the gas, the Norwegian oil company Statoil filters out the carbon dioxide and injects it into a sandstone formation half a mile... 

Tapped-out oil and gas fields are full of drill holes that could leak the carbon dioxide. The stored gas might also seep into groundwater pools. But the North Sea project seems to be working well. Seismic images under the ocean floor show that a thick layer of clay capping the sandstone is sealing in the millions of tons of carbon dioxide injected. 

FIGURE 3.7 Diagram showing effects of sedimentary structures and textures on the flow of fluids in a point-bar sandstone reservoir. The cross-bedded unit is coarser grained and is inferred to have better reservoir properties (i.e., permeability) than the overlying rippled unit (A). Uneven advance of injected fluids illustrating permeability variations results from differences in reservoir quality. (Modified after Ebanks, 1987.)... 

Koido, Furusawa, and Moriyama [206] used a technique based on the steady-state test method for reservoir rock, sandstone, and other porous media. In this method, a DL is sandwiched between similar DLs on the inlet and outlet sides. The material on the inlet is used to guarantee homogeneous distribution of liquid water in the planar direction, while the material at the outlet minimizes the flow in the outlet. Liquid water is introduced first and then a constant flow rate of air is injected. Once it is at steady state, the pressure difference between the inlet and outlet is measured. The sample is then weighed and the permeability is calculated in a way similar to that of Nguyen and colleagues [205]. 

Both NaCI and CaCb-rich brines are thought to have circulated at the base of the sandstones at minimal P-T conditions of 150 20°C and 1250 250 bars. The low-saiinity fluid is slightly warmer and is thought to have circulated at depth before being injected at the base of the sandstones. The two brines and the low-salinity fluid were mixed and trapped at the favour of pressure decrease from lithostatic to hydrostatic regime at the time of U deposition. 

The Rose Run Sandstone is the best characterized of the Cambrian sandstones because it is also an oil and gas reservoir (Fig. 3). It is also the only one of the Cambrian sandstones that is known to retain its sandstone composition in the eastern part of the state rather than passing laterally into carbonate. The Rose Run Sandstone is a sandy layer in the middle of the Knox Dolomite (Fig. 4), which across much of eastern Ohio lies at depths suitable for injection of supercritical C02 (Fig. 3). The Rose Run Sandstone was deposited in a passive margin phase of the Appalachian Basin and consists of interbedded layers of carbonate, primarily dolos-tone, and sandstone (Fig. 5). The sandstone is compositionally mature, consisting largely of quartz. Subordinate reactive minerals are the alkali feldspars and locally abundant glauconite (Fig. 5). Dolomite and quartz are the dominant cements (Janssens 1973 Riley et al. 1993). 

Estimates of storage capacity based on simple flow and equilibrium geochemical models indicate that the Rose Run Sandstone, by itself, potentially can store 30 years of emissions from the five largest coal-burning power plants in eastern Ohio. Ultimately the injected C02 can dissolve into the brine and be converted to the stable, immobile, carbonate mineral phases, primarily siderite, dawsonite, and calcite. 

Liu, L., Suto, Y., Bignall, G., Yamasaki, N. Hashida, T. 2003. C02 injection to granite and sandstone in experimental rock/hot water systems. Energy Conversion and Management, 44, 1399-1410. 

Acid-in-oil emulsion can extend the propagation of acid considerable distances into a reservoir because the continuous (oil) phase prevents or minimizes contact between the acid and the rock [4,678,689]. Emulsification also increases viscosity and will improve the distribution of the acid in layered and heterogeneous reservoirs. Acidizing foams are aqueous, in which the continuous phase is usually hydrochloric acid (carbonate reservoirs) or hydrofluoric acid (sandstone reservoirs), or a blend, together with suitable surfactants and other stabilizers [345,659]. Foaming an acidizing fluid increases its effective viscosity, providing mobility control when it is injected [678]. 

Table II lists the micromodel experiments performed in this study. Only two micromodels, the Reservoir Sandstone (RS) and the "Patio Stone (PS), were used. In these experiments the performance of different injection schemes and the effects of surfactant on gas displacement of water were investigated.

Reservoir Sandstone (RS) Micromodel. The RS micromodel was used in a variety of experiments examining the effects of surfactant, foam quality, injection scheme and pressure level on foam displacement efficiency and flow patterns. Various gases and brines or surfactant solutions were used, primarily field injection gas and brine, and the surfactant AES (trade name Alipal CD-128) at a concentration of 0.5 wt.%. 

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