Finite-Element Modeling of Spontaneous Potential in an Axisymmetric Reservoir Model with Account of Its Shale Content

(1) This article is devoted to the development of a theoretical and algorithmic basis for numerical modeling of the spontaneous potential method (SP) as applied to the study of sandy-argillaceous reservoirs. (2) In terms of coupled flows, we consider a physical–mathematical model of SP signals from an electrochemical source, with regards to the case of fluid-saturated shaly sandstone. (3) An algorithm for 2D finite-element modeling of SP signals was developed and implemented in software, along with its internal and external testing with analytical solutions. The numerical SP modeling was carried out, determining the dependences on the reservoir thickness and porosity, the amount of argillaceous material and the type of minerals. We performed a comparative analysis of the simulated and field SP data, using the results of laboratory core examinations taken from wells in a number of fields in the Latitudinal Ob Region of Western Siberia. (4) The results of the study may be used either for the development of the existing SP techniques, by providing them with a consistent computational model, or for the design of new experimental approaches.

Finite-Element Modeling of Spontaneous Potential in an Axisymmetric Reservoir Model with Account of Its Shale Content

(1) The article is devoted to the development of a theoretical and algorithmic basis for numerical modeling of the spontaneous potential method (SP) as applied to the study of sandy-argillaceous reservoirs. (2) In terms of coupled flows, we consider a physical-mathematical model of SP signals from an electrochemical source, with regard to the case of fluid-saturated shaly sandstone. (3) An algorithm for 2D finite-element modeling of SP signals was developed and implemented in software, along with its internal and external testing with analytical solutions. The numerical SP modeling was carried out, with determining the dependences on the reservoir thickness and porosity, the amount of argillaceous material and the type of minerals. We performed a comparative analysis of the simulated and field SP data, using the results of laboratory core examinations taken from wells in a number of fields in the Latitudinal Ob Region of Western Siberia. (4) The results of the study may be used either for the development of the existing SP techniques, by providing them with a consistent computational model, or for the design of new experimental approaches.

Improvement of Sorption Parameters of Nickel Ions on Bentonite in the Result of its Irradiation by Microwaves

The adsorption isotherms of nickel ions from aqueous solutions on bentonite, a natural argillaceous material, previously prepared using ultrahigh-frequency electromagnetic waves ("microwaves") were researched in the article. The phase composition of the sorbent was studied by applying the X-ray powder method. Bentonite sample being pre-wetted and irradiated by microwaves shows 2.7 times better sorption properties than the untreated (native) sample, which was shown on the example of the adsorption process of nickel ions from model solutions in static conditions. The sorption parameters prepared by using the "microwaved" and the native samples of bentonite were calculated according to the Langmuir adsorption equations. The barrier density of nickel in the irradiated sorbent is 16.4 mg/g (0.28 mmol/g), whereas for native bentonite the value of the analogous parameter is 6.0 mg/g (0.10 mmol/g). The reason for such an increase in sorption properties may be the change in the crystalline structure and distribution of micropores on the surface of the sorbent under the action of "microwaves" in the aqueous medium. The determinants in the pre-preparation of sorbent by "microwaves" are the ultimate power and time of irradiation.

Occurrence of palygorskite in Tertiary sediments of western Egypt

The presence of palygorskite in soils and sediments of the Middle East countries has been widely reported: in Syria (Muir, 1951), Israel (Yaalon, 1955; Barshad et al., 1956; Ravikovitch et al., 1960; Singer, 1971; Singer & Amiel, 1974; Yaalon & Wieder, 1976), Iraq (Al-Rawi et al., 1967; Eswaran & Barzanji, 1974), Lebanon (Lamouroux et al., 1973), Jordan (Wiersma, 1970; Shadfan, 1983; Shadfan & Dixon, 1984; Shadfan et al., 1985) and Saudi Arabia (Aba Husayn & Sayegh, 1977; Elprince et al., 1979; Mashhady et al., 1980; Viani et al., 1983; Lee et al., 1983; Mackenzie et al., 1984; Shadfan & Mashhady, 1985). In Egypt, Elgabaly (1962) indicated the predominance of palygorskite in some of the soils in the western desert and proposed that the mineral had formed from calcareous argillaceous material in a saline lagoon. Hassouba & Shaw (1980) found palygorskite to be a major component of the clay fraction in caliche crusts in the coastal plain of north-western Egypt and considered that the palygorskite had formed authigenically in that environment.