Intra-contour water-flooding

INTRA-CONTOUR WATER-FLOODING (EN: contour flooding; DE: Intrakonturwasserfluten, Randwasserfluten; FR: injection d'eau centrale; ES: inyeccion de agua con circulacion interna; RU: внутриконтурное заводнение) is the method for the development of the petroleum fields, in case of which the maintenance or the restoration of the balance of the layer energy is performed using the injection of the water immediately into the petroleum-saturated part of the petroleum (productive) layer.

The intra-contour water-flooding is the most intensive and economically effective method for the impact onto the petroleum layer. With the usage of the intra-contour water-flooding, within the USSR, there is extracted approximately 3/4 of all the petroleum (1980). According to the character of the mutual positioning for the petroleum-extracting and water-injecting boreholes, they distinguish several varieties of the intra-contour water-flooding. One of these varieties is the water-flooding with the "cutting" of the reservoir using the rows of the water-injecting boreholes into the individual places (areas), which are being developed independently one from another as the independent reservoirs (for example, the development of the Romashkinskoe field within the Tatar ASSR, and of the Samotlor field within the Tumen province of the Russian Federation). They position the chains of the injecting boreholes along with or transverse to the longitudinal axis of the structure. There has obtained the broad distribution (for example, at the Mukhanovskoe, and Arlanskoe fields within the Volga region, and at the Uzenskoe field on the Mangyshlak peninsula) the scheme with the transverse "cutting" of the petroleum reservoir with the elongated shape into the individual places, namely, blocks (the so-called blocked water-flooding). Between the rows of the injecting boreholes, they usually place 3 or 5 rows of the extracting boreholes (the three-row and five-row systems for the intra-contour water-flooding).

For the increasing of the final petroleum yield, and also of the tempos for the extraction, there are included into the schemes for the intra-contour water-flooding the additional water-injecting boreholes, namely, in the majority of the cases, the part of the petroleum-extracting boreholes, prevalently of the water-flooded boreholes. There are created of these boreholes the new chains or individual locations for the water-flooding (the local water-flooding). At the petroleum layers with the sharply expressed zonal non-homogenity of the productive collector, they use sometimes the selective intra-contour water-flooding. In this case, the reservoir is drilled initially according to the uniform network, and later the part of the boreholes (usually 1/5-1/3), which are comparatively uniformly distributed throughout the entire area of the reservoir, and which are having the best productivity, are mastered for the injection of the water, that is, there is created the system (network) of the individual locations for the water-flooding. The most intensive type of the intra-contour water-flooding is the area water-flooding, in case of which the extracting and injecting boreholes are alternated one with another according to the determined sequence, thus being uniformly placed throughout the area of the reservoir. The major advantage of the intra-contour water-flooding is the possibility of the substantial increasing of the tempos of the extraction of the petroleum from the reservoir, not only on the account of the increasing of the quantity of the boreholes, but also on the account of the ratio of the injecting and extracting boreholes, of the increasing of the pressure within the injecting boreholes, and so on.