Technical-economic development indicators

Economic Part

In justifying the feasibility of placing wells in the outlying parts of the oil-water deposits, the marginal net pay thickness is determined by the formula:

Where h_o^min - net pay thickness, at least where stocks are not selected for economic reasons, m;

h_ef^owz - average effective net pay thickness of the oil-water zone;

μ₀- coefficient taking into account the difference in the physical properties of oil and water in the reservoir conditions;

A2 - limit water production wells.

In turn, limit the water cut production wells is determined by the formula:

Where A - the estimated marginal share of water.

The estimated marginal share of water is determined by taking into account the maximum allowable cost of mining a ton of oil (C_np), regulations, current economic costs of running a well (3_T *), one of the current flow rate of fluid (3_T**) and the peak flow rate per well (q₀):

For all objects of development designed to accommodate a minimum thickness of oil-water wells in the area of 4 m.

In all variants of the development is provided back-up wells. Reserve wells are provided in order to engage in the development of oil reserves in some areas, areas of thinning and dead zones that are not involved in the development of wells within the main fund of the contour their placement. Given the high heterogeneity of zonal and layered pay zones, the development of the selected items are covered by the same mesh density on the placement of wells so that the mesh of the two objects form a uniform square grid in the two higher density. The number of backup wells should be10% of the basic design of wells.

Limiting water cut off for wells for field Karakuduk substantiated by calculations of technological and economic indicators at the level of 97%.

Given the technical specifications for the design, depths, plan location, geological and physical characteristics and capabilities of extracting producing formations adopted the minimum thickness for placement of wells, etc. informed in the previous sections, all variants of calculation defined technological development indicators.

The calculations of technological parameters are made using the software package "Project", developed in the laboratory optimization and design of oil field development institute "NIPIneftegas"

The basis of hydrodynamic calculations put the actual data on the production rates of wells, reservoir productivity their heterogeneity, obtained during the test. Production rates of new wells justified given the number of wells tested on objects of the zonal index of heterogeneity in productivity and the reliability coefficient ξ formula:

x₁ -factor that ensures the reliability of at least 90%, confirming the design flow rates for a limited number of wells tested;

Where: n₀- number of project wells;

n_u-number of such wells;

V²_η-indicator of heterogeneity on the productivity of wells;

-coefficient taking into account reduction of the effective permeability due to the discontinuity and zonal heterogeneity;

Where: SI- area per one well;

V23- rate of zonal heterogeneity;

W2- share ofuncollektor;

d2- scale of variation of reservoir properties;

ξ3- coefficient of operation of wells showing the proportion of working days per year;

With the projected development of oil-saturated reservoir system allocated major maintenance facilities design I, II, III and IV Karakuduk field calculation of the coefficient of oil extraction was performed according to zones and categories of reserves coefficient method as follows:

Where: K₁ - net enrollment ratio in wells, showing the proportion of drained of oil deposits in the system location of wells;

K₂ - Coefficient of oil displacement in a micro-volume of the reservoir;

Net enrollment ratio in wells is determined by the following relation:

Where: K₁^’ - coefficient of involvement in the commercial development of geological oil reserves dedicated to the oil-water areas K₁^’’ - enrollment in the process of repression. In the calculation K₁^’- for the pure oil zone is assumed to be 1, and the op-water zones is calculated the following formula:

Where: h_ef^woz - the average effective thickness of the oil-water zone, m;

h_o^min - Net pay thickness, at least where production wells are not placed.

Enrollment ratio in the process of displacement field for the selected objects is determined by the formula:

Where: W-index discontinuity (the proportion of uncollektor area of productive layers); d-step random changes in reservoir properties of oil reservoir, km;

S’- the area of ​​oil accumulation per well, km2;

m_p - Number of rows of wells located in a strip between two rows, when the marketplace and the electoral system, flooding, if the ratio of production and injection wells m=‹3 then m_p=1, if m=6-8 then m_p=2.

Parameters to determine the scope of the displacement of Jurassic productive horizons in average W = 0.07, d = 0.250 m

K₃ - Coefficient of flooding, showing the fraction of mobile oil extraction.

Where V² - the resulting estimated heterogeneity:

V₁² and V₃²- accordingly lamellar and zonal heterogeneity of productive formations;

2/(1+ m) – fraction of the area strata, within which is a contraction of the front displacing substance;

Where μ* - the ratio of the mobilities of the displacing agent and the oil at reservoir conditions;

μ _o - Viscosity of the oil;

μ_ws - The viscosity of the displacing substance;

m- The ratio of production and injection wells;

ΔL- The mean deviation of the borehole from the design point;

For a basic version of the design using conventional water-flood recovery factor approved by the quantity is not achieved (less than the approved 2.5%).

Comparison of the ORF shows that the highest oil recovery is achieved in the case of two variants of the development. In this case, the final recovery factor than approved in the whole of the deposit by 0.3%.

None of the four other payment options for development, including the recommended option 4 does not provide an approved oil recovery factor on performance targets. However, the ultimate oil recovery in the case of four less than the approved version of the 0.6%, in the case of realization of the final version of the three recovery factor approved by less than 0.4%.

Increase the recovery factor of 3 option (relative to 1 base case) is associated with improved method of water flooding through the use of nonionic surfactant injection.

The increase in recovery factor of 4 variant is associated with improved method of water flooding through the use of the field enhancement of oil recovery method - rotary-cyclic water-flooding.