Оценка применимости полимерного заводнения с использованием теории нечетких множеств

Еремин, Н.А.; Сурина, В.В.; Приказчикова, М.С.

Авторы: Еремин Н.А., Сурина В.В., Приказчикова М.С.
Журнал: Нефтяное хозяйство
Номер: 4
Год издания: 1994
Издательство: Нефтяное хоз-во
Местоположение издательства: М.
Первая страница: 54
Последняя страница: 57
Аннотация: N. A. Eremin, V. V. Surina, M. S. Prikazchikova (OGRI RAN) Estimation of polymer flooding using a fuzzy set theory, Oil Industry, April 1994, pp.56-57. Successful use of any reservoir stimulation method depends on process and economic efficiency. Appropriate selection of methods and implementation sites strongly relies on specific geological a physical conditions in the area. An expert estimate method is one of the choices that take into account the impacts of geological and physical parameters on stimulation efficiency. The approach is centered on the principle of agreement between geological and physical parameters of the field (object) and applicability criteria for the analyzed method. A currently used stimulation selection method relies on comparisons with averaged geological and physical parameters and thus cannot account for their variability within a bed. Yet, heterogeneity of lithological and non - traditional rock features, along with physical and chemical properties of reservoir liquids, is known to be considerable. For these reasons, selection of a stimulation method based on comparisons with averaged bed parameters alone often cannot be justified appropriately. An approach based on the fuzzy set theory is free from the disadvantages mentioned above. This theory primarily operates the notions of accessory function and extent and an applicability factor (A. B. Zolotukhin, N. A. Yeremin, L. N. Nazarova, and E. N. Ponomarenko, «Fuzzy set theory applied to selection of oil bed stimulation methods», Neftyanoye Khozyaistvo, No. 3, 1991, pp. 21 – 26). Applicable to any geological and physical parameter it is possible, in any point within a bed, to estimate accessory factors for various impact methods, to establish related applicability zones and to access the zones impacted by various methods. The approach has been used to estimate the opportunities for polymer treatment in Minibayevskaya area of Romashkinskoye and Fedotovskaya area of Novo-Yelokhovskoye field in Tataria. The study areas have been selected purposefully to estimate polymer treatment implementation opportunities. Early comparison of averaged geological and physical parameters for the objects with the applicability criteria helped to recommend its use for enhanced oil recovery. High bed heterogeneity is typical for Minibayevskaya area, while high viscosity of reservoir oil is a feature of the Fedorovskaya area. For this reason it is extremely important to consider the applicability of polymer flooding for the objects, using the above mentioned method to select the bed zones which are most favorable for polymer injection. At the first stage of polymer treatment justification, porosity, permeability and oil - saturated thickness maps were created for major development objects. In the Minibayevskaya section, the primary oil reserves have been attributed to Pashian deposits on Low-Frans sub —layer, and are selected as a D1— horizon development area. The D0 bed in Kynov horizon was tapped as separated lenses, through a number of wells. In terms of both porosity and permeability, the D0 bed has been found to be heterogeneous, and a number of zones with worsened (compared to average) properties was found. Maximum permeability and porosity for the object were 1,114 sq km and 21% accordingly. Effective oil- saturated thickness was between 1 and 4 m for aleurolites and 1.6 — 6 m for sandstones. The polymer flooding applicability map, for porosity and permeability, is shown in Fig. 1. It can be seen that the distribution of polymer flooding zone applicability for the D0 bed is extremely non-uniform. Vast zones featuring maximum applicability factors (Cj = 1) are present only in the southern and south-eastern portions on the Minibayevskaya area. For the rest part, allocation of high applicability zones (Cj = 1), medium (0) and poor conditions (Cj = 0) are extremely non —uniform. The coverage of zones featuring applicability equal unity is much broader for permeability than for porosity. And the most contrasting distribution of zones, applied to polymer flooding success rate, is more typical for permeability rather than porosity. The polymer flooding applicability map for the total DO bed is shown in Fig. 2, a. The D1 bed includes eight interbeds: А, В1,B2, B3, V, G, G2 + 3, and D. For each interbed. porosity applicability maps have been created. The best opportunities for polymer flooding, in terms of porosity, exist for G1 and G2 + 3 interbeds featuring vast zones with maximum applicability factors (Cij = 1). Distribution of zones with various applicability conditions is nextremely non —uniform for a number of interbeds. To build the applicability maps for the total D1 bed, the thickness-average porosities and permeabilities have been used. Fig. 2, b highlights the polymer flooding applicability map for the D1 bed that is known to have vast zones with maximum applicability factors. In the total Minibayevskaya area, the maximum applicability factor (Cj = 1) was obtained in 981 well, intermediary values (0) were found for 116 wells and the minimum (Cj = 0) shown for 352 wells. According to the estimates provided, the polymer flooding coverage of reserves can be as high as 21% of the initial balance figures. Similar calculations have been provided for Novo —Yelokhovskoye field in the Fedotovskaya area. In the terrigeneous thickness of the lower carbon in the Novo —Yelokhovskoye field, two collectors can be selected, T2 and Vv1; they are attributed to Tulski and Bobrikovski horizons. The pay—out bed in the Tulski horizon has 3 m thickness, or 1.3 m on an average, 0.194 porosity and 0.055 sq mkm permeability, according to hydrodynamic study data. Initial comparison of the abovementioned parameters for the Tulski horizon with the polymer flooding applicability criteria excludes this treatment in the object due to technological problems possible while injecting water — dissolved polymers and their move in the bed. At the object analyzed. VV1 bed thickness varies within 1 — 17.4 m, or 4.3 m on an average for oil zones, with 0.64 — 1.78 sq mkm permeability and 0.2 — 0.216 porosity. It can be seen in Fig. 2. с that in general for the area, the applicability factor of polymer flooding is at maximum — to— middle levels while the zones of poor applicability are occasional by character. The maximum applicability factor (Cj = 1) was noted for 112 wells, the minimum (Cj = 0) was in 48 wells, and middle values (0) were found in 11 wells. The polymer flooding coverage is 67.8% of the balance reserves in Novo —Yelokhovskoye field.
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Оценка применимости полимерного заводнения с использованием теории нечетких множествстатья

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