Permeability from formation solids

Flow-through methods. In these methods, only one sample is used and is successively brought into equilibrium with solutions of increasing concentration. Most frequently, the sample is initially equilibrated with the pure solvent. Each increase in concentration produces an adsorption of solute by displacement of solvent from the solid surface. The changes in concentration produced by adsorption are usually monitored by the same techniques as those used in the immersion methods, except that they are now located on-line. A general requirement of these methods is that the sample can form a permeable bed and does not block the filter this usually requires a grain size over, say, 2 pm and prevents any tendency to gel formation. 

Permeable intervals can be identified from a number of logging tool measurements, the most basic of which is the caliper tool. The caliper tool is used to measure the borehole diameter which, in a gauge hole, is a function of the bit size and the mudcake thickness. Mudcake will only build up across permeable sections of the borehole where mud filtrate has invaded the formation and mud solids (which are too big to enter the formation pore system) plate out on the borehole wall. Therefore the presence of mudcake implies permeability. 

An injectivity test is performed using clean, solids-free water or brine. If a low fluid loss completion fluid is in the hole, it must be displaced from the perforations before starting the injecting. This test will give an idea of the permeability of the formation to the cement filtrate. 

Reduced injectivity due to formation damage can be a significant problem in injection wells. Precipitate formation due to ions present in the injection water contacting counterions in formation fluids, solids initially present in the injection fluid (scaling), bacterial corrosion products, and corrosion products from metal surfaces in the injection system can all reduce permeability near the wellbore (153). The consequent reduced injection rate can result in a lower rate of oil production at offset wells. Dealing with corrosion and bacterial problems, compatibility of ions in the injection water and formation fluids, and filtration can all alleviate formation damage. 

This paper reports an investigation of the effects of porous solid structures on their electrical behaviour at different frequencies (from 100 Hz to 100 kHz). For that, we study different parameters such as formation resistivity factor, cementation factor, chargeability, resistivity index and saturation exponent. Different porous solid structures are quantified from the petrographic image analysis and Hg-injection technique. Then, by using different models we obtain the permeability prediction from the electrical behaviour and structure parameters. 

Fig. 5 Chargeability factor A/can be predicted by a Fig. 6 Permeability prediction from electrical multi-linear model composed by different behaviour and structures parameters of porous parameters formation factor F, water porosity O, solids, k Katz and Thompson model Hg-specific surface Asp and water permeability k for kjsc Johnson, Schwartz and co-workers different textures. model.

Oil producers will typically set standards for oil-in-water content ranging from less than 10 ppm in very light crude oils to several hundred parts per million in very heavy crude oils. These specifications are usually site-specific and are dependent on equipment available and crude-oil type. Oil producers in Canada usually have the advantage of disposal wells or water-flood schemes in which produced water is disposed. Failure to meet self-imposed oil-in-water limits usually results in loss of hydrocarbon product back to the formation. For an oil production facility that disposes of 1000 m of water per day with an oil content of 1000 ppm, 365 m of oil is lost per year. At 25 (Canadian) per barrel, this amount of oil translates to a product loss worth approximately 57,000 per year, plus any maintenance costs and well stimulation costs to restore injectivity lost as a result of formation plugging from oil-wet solids. Oil-wet solids in water-flood systems may damage formation permeability and reduce recovery. 

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