RU2283426C2 - Method for oil and gas field development - Google Patents

Abstract

FIELD: multizone oil and gas field development, particularly to control hydrocarbon field development at later operation stage.

SUBSTANCE: method involves increasing productive reservoir sweep efficiency under the action of processing agent to be injected into formation through injection well; producing hydrocarbon product through producing wells. Regime of processing agent supplying into injection well and/or hydrocarbon product extraction from producing well is shifted into unsteady regime by pressure change during processing agent supplying into injection well and by product flow rate change, which is in anti-phase with above processing agent supply, through equal time intervals. Then cross-correlation pressure and flow rate functions in injection and production wells are determined. Frequency properties of production reservoir, namely reservoir pressure, filtering and capacitance coefficients, for instance permeability, porosity, water permeability and productivity, are determined from above function parameters. During field development rate of hydrocarbon product extraction from producing well and time of hydrocarbon product extraction are maintained to provide maximal ratio of hydrocarbon product displacement coefficient after the action to that before above action.

EFFECT: increased final gas and oil recovery from reservoirs due to hydrocarbon product displacement control.

5 cl, 4 dwg

Description

The invention relates to the field of development and operation of hydrocarbon deposits on land and in the water area, in particular to methods for increasing oil and gas recovery of productive reservoirs with a complex geological structure.

It can be most effectively used in the development and operation of hydrocarbon deposits at a late stage of operation, characterized by a multi-tiered geological structure, in which the hydrocarbon deposits are separated, located at great depths and are associated with non-structural type hydrocarbon traps, as well as with low-amplitude hydrocarbon traps. local uplifts.

The invention can be used to control the development and further development of hydrocarbon deposits in the tertiary operation of complex multi-layer deposits, when it is extremely necessary to involve weakly drained, deadlock and stagnant zones into operation.

A known method of developing hydrocarbon fields (US patent 4408664, MKI E 21 B 43/20, E 21 B 43/27, NKI 166/263, 1983), according to which a method for increasing oil recovery and oil recovery from productive formations at a late stages of operation by injection into the reservoir through injection wells of injected water with special additives and subsequent displacement of the rim of the injected water to production (production) wells during the selection of oil in the specified volume.

Significant disadvantages of this method are the low technological and economic efficiency of the proposed technology, because There are no objective criteria for the optimal values of injection regimes and volumes of injected water, including and rims in layers with a complex geological structure; in addition, the determination of the amount of oil taken from the reservoir depending on the reservoir properties determined by core, has a high error due to the study of only the borehole zone, requires laborious research in laboratory conditions, drilling of special wells for coring and additional downhole geophysical studies, which significantly reduces technological and economic efficiency of the method.

There is also a known method of developing hydrocarbon fields (RU, patent 2122630, MKI E 21 B 43/20, 43/22, 1997), when also during tertiary development at a late stage of operation of the hydrocarbon field, oil is displaced from the reservoir by selecting the optimal composition of injected process fluids for the formation of modified polymer dispersed systems.

The disadvantages of this method are its low efficiency when used in flooded heterogeneous productive formations with a complex geological structure, in addition, the lack of regulation of the flow of pumped process fluid and oil selection significantly reduces its economic efficiency.

The closest in technical essence to the invention is a method of developing hydrocarbon deposits (RU, patent 2188315, MKI E 21 B 43/22, 2002), which includes increasing the coverage of the reservoir by the influence of the injected technological agent at a late stage of development of oil deposits by adjusting the filtration the resistance of the flooded volume of the reservoir for water based on the use of special water-insulating compositions containing polymer-containing clay suspensions and modifying chemicals.

The disadvantage of this method, along with its low economic and technological efficiency due to the subjective decision-making on the impact on the flooded reservoir at a qualitative level, is the complete lack of information on the parameters of the flooded reservoir, including information on the phase permeability and water saturation of the reservoir; in addition, the lack of information on the exact boundaries of the roof and the bottom of the formation and on the spatial position of the gas-liquid contacts in the space between the injection and production wells does not allow controlling the front of oil displacement from the formation and accurately regulating the development of the oil reservoir. Moreover, the local impact only on the watered reservoir, and not on the multi-layer multi-layer hydrocarbon field as a whole, significantly reduces the technological and economic efficiency of the known method.

The aim of the invention is to increase the final gas and oil recovery of productive reservoirs of a multilayer oil and gas field by controlling the process of displacement of hydrocarbons.

This goal is achieved by the fact that in the known method of developing hydrocarbon deposits, based on increasing the coverage factor of the reservoir by the action of an injected technological agent using an injection well and selecting a product using an producing well, the mode of supplying the technological agent to the injection well and / or the selection of hydrocarbon raw materials from the producing well into the unsteady one at the same set time intervals, for the same time intervals the functions determine the cross-correlation functions of flow and pressure at the mouth of the injection and the mouth of the producing well, according to the parameters of the cross-correlation functions, the transfer and transition functions of the reservoirs, they select, evaluate the parameters of the reservoir, the coefficient and the front of the displacement of hydrocarbons and establish optimal values and time intervals for selection hydrocarbon feedstock in the producing well, depending on the reservoir properties of the reservoir and the displacement coefficient.

To increase the displacement coefficient, the mode of supplying the technological agent and the selection of hydrocarbon feedstock is switched to non-stationary by means of stepwise changes in the pressure inside the injection well and stepwise, out-of-phase flow, changes in the production rate of the production well at the same time intervals not exceeding the duration of the transitional characteristic of the formation.

The optimal values of the flow rate, pressure, volume and time of the supply of the technological agent are determined by the maximum values of the displacement coefficient, determined by the ratio of the volumetric values of the oil and gas saturation coefficient to the water saturation coefficient, proportional to the ratio of the transmission characteristics of the oil and gas saturated and water saturated parts of the reservoir and the duration of the transitional characteristics.

To increase the reliability of isolation of the water-saturated part of the reservoir and to maintain the constancy of reservoir pressure, an alternating cyclic injection of a water-insulating composition and a technological agent (solvent of oil, steam, gas, etc.) is carried out with injection time intervals that do not exceed the duration of the transition characteristic and equal speeds .

To increase the coverage of the formation by volumetric displacement of hydrocarbon feedstock in the productive part of the formation, horizontal horizontal shafts are cut from the main well of the injection well, in each of which the displacing technological agent (solvent) and displacing gas (or steam) are alternately pumped with equal speeds of both components and time impacts not exceeding the duration of the transitional characteristics of the reservoir.

Figure 1 presents a functional diagram for implementing the method.

Functional diagram includes production well 1 (or a number of wells), injection well 2 (or a number of wells), 3; 3 ¹ - pressure sensors at the mouth of the injection and mouth of the producing wells, respectively; four; 4 ¹ - flow sensors at the mouth of the injection and the mouth of the producing wells, respectively; 5 - productive part of the reservoir; 6 - water-saturated part of the reservoir.

Figure 2 shows an example of lateral determination of reservoir properties, oil and gas saturation and the displacement coefficient for a multilayer oil and gas condensate field.

Figure 3 as an example of the implementation of the claimed method shows a structural map of the hydrocarbon field in the frequency representation before exposure (Fig.3A) and after exposure (Fig.3b) using a number of horizontal wells after three years of operation of the field. The injection and production wells are cased with a string, have an open (perforated) part of the wellbore at predetermined intervals of the geological section, are sealed mouths and are equipped with blowout control equipment.

The method is implemented according to the following sequence of operations.

After establishing the exact boundary of the water-oil (or gas-liquid) contact of the oil-and-gas complex at the late stage of hydrocarbon field development using injection well 2 (or a number of injection wells), a special water-insulating composition is injected into the water-saturated part of reservoir 6. To increase the contact surface from the main trunk of the injection well below the OWC, a number of lateral horizontal shafts are cut (or additional perforations are created). After creating a reliable water-insulating screen in the upper water-saturated part of reservoir 6, they switch to an unsteady stepwise supply 2 of a technological displacing agent (oil, gas, steam, polymer compositions that reduce the viscosity of oil, etc.) to the productive part of reservoir 5 at equal time intervals with the help of a system of multilateral horizontal trunks above the VNK or with the help of additional perforations. To increase the contact surface and increase the volumetric coefficient of coverage of the productive part of reservoir 5 from the main trunk of production well 1 (or a number of production wells), horizontal sidetracks located in the productive part of reservoir 5 above the system of horizontal injection shafts are also formed with the formation of a spatial “grating” above VNK.

In the time interval of the unsteady supply of the technological agent, a stepwise, out-of-phase supply is carried out, a decrease (increase) in the selection of hydrocarbons from the producing well 1 by stepwise adjusting the pressure or flow rate at the wellhead 1 (for example, using an adjustable nozzle or changing the diaphragm). As a result, there is an alternating stepwise change in the dynamic reservoir pressure in the injection well - reservoir - production well system with the regulation of their values to the maximum possible using sensors 3, 3 ', 4, 4'. In the case of a stepwise decrease in pressure on the productive part of the reservoir, there comes a time when the pressure in the producing well 1 will be less than the reservoir pressure, in this case, an intensive inflow of hydrocarbon feed from the productive part of the reservoir begins and well 1 is transferred to the maximum selection of hydrocarbons.

In the process of stepwise regulation of flow and pressure at the mouths of wells 1 and 2, the coefficients of mutual correlation of pressure and flow rates are measured using sensors 3, 3 ', 4, 4'. The results of the comparison are subjected to functional transformations when the cross-correlation coefficients are translated into the desired reservoir parameters, such as reservoir pressure, permeability, porosity, hydraulic conductivity, productivity coefficient, and displacement coefficient.

The calculation of the desired parameters is carried out according to the following algorithms. The basis for identifying the regulation of the system by the injection well - reservoir - production well is the solution of the integral equation

Where:

R _1,2 (τ) is the cross-correlation function of the flow and pressure signals at the wellhead 2 and the wellhead 1;

R _1,1 (τ) is the autocorrelation function of the flow and pressure signals at the wellhead 1;

τ is the time shift between the signals in the injection and production wells, s;

θ is the integration variable;

K (t) is the impulse response characteristic of the injection well-fall-production well system.

Where:

π is the number π (π = 3.14);

e is the natural logarithm (e = 2.718);

i is the imaginary number;

ω is the circular frequency, rad / s;

t is the time, s;

- комплексный коэффициент передачи системы.

- the integrated transmission coefficient of the system.

By the complex transmission coefficient of the system, the dynamic amplitude-frequency and phase-frequency characteristics of the system are estimated.

The duration of the impulse response is defined as:

The value of reservoir pressure is estimated as:

where K ₁ is the coefficient of cross-correlation between the costs at the wellhead 2 and the wellhead 1;

P ₂ , Q ₂ - pressure and flow rate of the technological agent at the wellhead 2, respectively.

Formation porosity is defined as:

where Q ₁ - the flow rate at the wellhead 1 for the time interval;

t _c is the duration of the exposure step.

The permeability of the formation is defined as:

where n is the number of time intervals.

The hydraulic conductivity of the formation is estimated as:

G _p = K ₂ / K ₁ ,

Where:

K ₂ - the coefficient of cross-correlation between pressures at the mouths of the injection and production wells.

The coefficient of productivity is defined as:

where T is the period of the selection of the hydrocarbons from the well 1.

In the above formulas, the coefficients K ₁ ; K ₂ is defined as:

;

;

;

- автокорреляционные функции расхода и давления на устье добывающей и устье нагнетальной скважин соответственно.Where

;

;

;

- autocorrelation functions of flow and pressure at the mouth of the producing and mouth of the injection wells, respectively.

The current coefficient of displacement of hydrocarbon by a technological agent is estimated as:

- коэффициент вытеснения до воздействия;Where

- coefficient of displacement before exposure;

- коэффициент вытеснения после воздействия;

- displacement coefficient after exposure;

,

соответственно.To _ng , To _vn - the coefficients of volumetric oil and gas saturation and volumetric water saturation, determined by the transfer characteristics

,

respectively.

For various types of collectors, the values of the coefficients K ₁ , K ₂ are in the range 0.27-0.65.

. При этом оптимальные величины дебита добывающей скважины и временные интервалы отбора УВС устанавливают, поддерживая в процессе разработки максимальные значения

. Для количественной оценки К_нг, К_вн залежи используют величины частотных свойств передаточных характеристик, например объемные спектрально-временные плотности.As an optimization criterion, the value of the maximum volume of the productive part of the deposit V _prod.pl → max, involved in operation during the exposure, corresponding to the maximum ratio

. At the same time, the optimal production rate of the producing well and the time intervals for the selection of hydrocarbons are established, supporting the maximum values during the development process

. For a quantitative assessment of K _ng , K _vn deposits use the values of the frequency properties of the transfer characteristics, for example volumetric spectral-temporal densities.

In the case of the multilayer structure of the hydrocarbon field, the number of time intervals for the impact of n _{in is} chosen n _in > n _p +1, where n _p is the number of reservoirs in the multilayer field.

As an example of the implementation of the proposed method, Fig. 2 shows a depth section of the current oil and gas and water saturation, graphs of the porosity coefficient K _p and the displacement coefficient K _in lateral for productive reservoirs (yellow-green color) of a multilayer oil and gas condensate field, the upper part of which is at a late stage operation (indicated by a dotted line).

The duration of the impulse response characteristics for the oil and gas saturated part of the field with an effective power of H _eff = 10-50 meters is g _k = 1.3-3.6 · 10 ³ s; for the water-saturated part g _to = 7.2-24 · 10 ³ s.

Figure 3 shows an example of the implementation of the regulation of the volumetric coverage coefficient and the displacement coefficient of hydrocarbons using a system of multilateral horizontal wells drilled by cutting from the main well of the injection well into the productive part of the reservoir located in the period of falling production in one of the fields in the North of the Timan-Pechora oil and gas region . The structural map of the roof of the deposit is based on the results of the assessment of the areas of spectral densities of the transfer characteristics of the productive part of the reservoir (yellow-green color) and host rocks (orange color) in the frequency range 0.1-100 Hz.

After the impact, the productivity of the controlled production well increased by 8 times and was maintained at a stable level for the observed three years.

Compared with the known technical solutions, the proposed method allows with high efficiency almost in real time to control the volumetric coverage coefficient and the displacement coefficient of hydrocarbons from multilayer complex deposits, which ensures the maximum extraction of hydrocarbons at a late stage of operation due to the creation of the optimal technology and system for the extraction of hydrocarbons directly in productive horizons themselves.

The high economic efficiency of the proposed technical solution, in addition to increasing the volume of recoverable hydrocarbon raw materials, is complemented by the absence of the need to drill additional injection and production wells and a reduction in the costs of additional exploration of fields due to the use of the fund of low-profit and inactive wells available at the production enterprise.

Claims (5)

1. The method of developing oil and gas fields, based on increasing the coefficient of coverage of the reservoir by exposure to an injected technological agent using an injection well and the selection of hydrocarbon raw materials from the producing well, characterized in that the mode of supplying the technological agent to the injection well and / or the selection of hydrocarbon raw materials from the producing wells into unsteady by changing the pressure of the injection of the technological agent into the injection well and out of phase the first injection of changes in the flow rate of the selected hydrocarbon feedstock from the producing well in equal time intervals, the cross-correlation functions of pressure and flow in the injection and producing wells are determined, the parameters of the cross-correlation functions determine the properties of the reservoir in the frequency representation - the reservoir pressure and its filtration and capacitive properties, such as permeability, porosity, hydraulic conductivity and productivity, while in the process of development the flow rate of the selected hydrocarbon feed I from a producing well and the time intervals for the selection of hydrocarbon feedstocks from operation support from the condition of the maximum value of the ratio of the coefficient of displacement of hydrocarbon feedstock after exposure to this coefficient before exposure. 2. The method according to claim 1, characterized in that the pressure in the injection well and the flow rate in the producing well change stepwise and in the exposure time not exceeding (1.3 ÷ 24) · 10 ³ s. 3. The method according to claim 1, characterized in that the flow rate, pressure, volume and time interval for pumping the technological agent into the injection well are set according to the maximum value of the coefficient of displacement of hydrocarbons. 4. The method according to claim 1, characterized in that solvents of oil, steam, gas are alternately pumped into the injection well in an unsteady mode with a water-insulating composition, equal speeds and exposure time not exceeding (1.3 ÷ 24) · 10 ³ s . 5. The method according to claim 1, characterized in that from the injection well bore, horizontal sidetracks are drilled, into each of which solvent and gas or steam are pumped alternately with equal speeds and exposure time not exceeding (1.3 ÷ 24) 10 ³ s.

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