Pressure porous-fracturing

Acid fracturing is an oil well stimulation process in which acid (HCl or HF, depending on the rock structure) is injected into an oil well at sufficiently high pressure to fracture the porous media or to widen existing natural fractures. Various principles of surface chemistry are employed in this process in order to avoid excessive and costly fluid loss, and to decrease the rate of acid spent. 

Mercury porosimetry (or intrusion) Measurement of the specific porous volume and of the pore size distribution function by applying a continuous increasing pressure oti liquid mercury such that an immersed or submerged porous solid is penetrated by mercury. If the porous body can withstand the pressure without fracture the Washburn equation, relating capillary pressure to capiUaiy diameter allows converting the pressure penetration curves into a size distribution curve. If a sample is contracted without mercury intrusion, a specific mechanical model based on the buckling theory must be used... 

Figure 2 shows a set of results for a catalyst powder (Super-D), manufactured by Crosfields Chemicals, Warrington, made from pellets by grinding with a pestle and mortar. Figure 2 portrays the extent of penetration of the pore volume as the pressure of mercury is increased. Also shown in the same figure are the results for pellets fractured into halfsize and quarter-size fragments. These results for powder, fractured pellets and whole pellets are to be used as a measurement framework for distinguishing the basic pore structure/pore size distribution of the interior porosity of the micro-porous particles and the intra-pellet pore spaces of the full pellet. 

In theory, a liquid can be pumped into any porous formation, provided no pressure or time constraints exist. In practice, chemical grouts must be placed at pressures consistent with good engineering practice and at rates that make the use of chemical grouts economically feasible. In the discussions that follow, it is assumed that those practical considerations are met for all conditions. It is also assumed, unless otherwise stated, that grout penetration into a formation is by permeation, not fracturing. 

Foamed Matrix Acidizing. Matrix addizing is a stimulation treatment used to remove damage near the wellbore without deating a fracture. The process involves the injection of a reactive fluid into the porous medium at a pressure below the fracturing pressure. The fluid dissolves some of the porous medium and consequently increases its permeability. 

A rock sample is considered with an initial permeability assumed to be lO m, both in the porous medium and in the element that will contain the fracture. Capillary pressure to start desaturation (air entry value) in the porous medium is assumed to be 0.3 MPa. 

Abstract This contribution deals with the modeling of coupled thermal (T), hydraulic (H) and mechanical (M) processes in subsurface structures or barrier systems. We assume a system of three phases a deformable fractured porous medium fully or partially saturated with liquid and a gas which remains at atmospheric pressure. Consideration of the thermal flow problem leads to an extensively coupled problem consisting of an elliptic and parabolic-hyperbolic set of partial differential equations. The resulting initial boundary value problems are outlined. Their finite element representation and the required solving algorithms and control options for the coupled processes are implemented using object-oriented programming in the finite element code RockFlow/RockMech. 

Coal is a kind of uneven double porous media made up of macro-cracks and micro-pores. Gas in coal seam remains in the macro-cracks and micropores in free state and adsorbed state. Once getting pressure relief, gas in coal seam begins to flow along the pores and fractures, while the absorbed gas is desorbed. Gas flow in Coal seam is actually a very complex process affected by many factors. In order to simplify the process, the coal seam gas flow model has the following assumptions—(Wang Xiaoliang, et. al, 2003). 

Adhesive penetration into wood can be categorized (i) on micrometer level as a result of the hydrodynamic flow and capillary action of the liquid resin from the outer surface into the porous and capillary structure of wood, mostly filling cell lumens, as well as fractures and surface debris caused by processing [5], and (ii) on sub-micrometer level as diffusion penetration into cell walls and micro- fissures. Hydrodynamic flow is initiated by the external compression force as a result of pressure applied to the wood surface to be bonded. The flow then continues into the interconnected network of lumens and pits, with flow moving primarily in the direction of lowest resistance [6]. The extent of utilization of an adhesive may be limited due to excessive penetration into the substrate, since this portion of the applied adhesive is lost within porous substrate structures for the adhesion effect. 

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