RU2550632C1 - Method of oil field development by horizontal and vertical well system using thermal impact - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: method of oil field development by a horizontal and vertical well system using thermal impact involves horizontal and vertical well drilling and equipment, so that vertical well bottom is located below horizontal well bottom at a design vertical distance of 3 to 7 m, formation of heating area by injection of combustible oxidising mixture (COM) and combustion initiator (CI) to ignite and warm-up the inter-well zone up to 100-200°C, depending on COM and CI type, and to establish hydrodynamic connection between wells; horizontal well is switched to liquid production by a pump, with continued supply of COM and CI to the vertical well to maintain burning and warming-up of the field to 250-350°C which is the temperature of independent burning of COM; afterwards, CI supply is stopped, and COM injection continues to maintain and promote burning along the horizontal wellbore. During construction, horizontal well is equipped with a filter with several zones along the horizontal section length. Before pump landing in the horizontal well, a liner with thermocouples installed inside it for temperature monitoring inside the well opposite to filter zones, that allows for serial opening of only one zone during turning and for shutting filter zones from bottomhole to wellhead. Zone adjoining the bottomhole is opened initially. After combustion initiation, if temperature in this zone falls down from the maximum achievable by combustion in the field conditions to 85-95°C, product pumping is stopped, the liner is turned from wellhead to a definite angle ensuring bottomhole zone shutoff and opening of the next zone used for further product extraction by pumping. After temperature in this zone changes from the maximum achievable by combustion in the field conditions to 85-95°C, this zone is closed by a turn of the liner opening the next zone from the bottomhole, and similarly zones are opened and shut in sequence till the last filter zone from the bottomhole.EFFECT: optimised operation of horizontal well, reduced power cost of its operation, expanded effective coverage of horizontal producer effect, reduced content of gas in the product extracted, enhanced depletion of oil field stock.1 ex, 3 tbl, 8 dwg

Description

The invention relates to the oil industry, in particular to thermal methods of oil and / or bitumen production by a system of vertical and horizontal wells.

A known method of developing a reservoir of high viscosity oil by in-situ combustion (RF patent No. 2087690, IPC E21B 43/243, publ. 08/20/1997, bull. No. 23), including creating a channel of communication between injection and producing wells in the reservoir, filling it with a permeable refractory material creating a stationary combustion zone in the channel.

The disadvantage of this method is the difficulty of determining the boundary of the influence of the combustion zone. Carrying out temperature control at the bottom of the producing well and analyzing the composition of the produced products in order to determine the combustion gases in the latter shows only the fact that the boundary of the producing well has been reached. In this case, it is impossible to change the propagation of the combustion front by pumping combustion gases through the production well. In addition, with horizontal movement of the combustion front, part of the heated oil due to gravitational forces moves to the bottom of the formation, burns and does not reach the producing well.

A known method of thermal oil production (RF patent No. 2054531, IPC E21B 43/24, publ. 02/20/1996, bull. No. 5), including the drilling of vertical and vertical-horizontal wells, hydraulic fracturing, ignition of the oil reservoir, control countercurrent movement of the focus combustion along the horizontal drilling channel with the control of its movement by changing the hydraulic resistance of the channel.

The disadvantage of this method is that during hydraulic fracturing, the spatial propagation of cracks can lead to a breakthrough of bottom water into the productive part of the formation and the decay of the combustion zone or an advance breakthrough of the combustion front along the crack into the producing well.

The closest in technical essence to the proposed method is a method of developing an oil reservoir using thermal stimulation (RF patent No. 2399755, E21B 43/243, publ. 09/20/2010, bull. No. 26), including drilling and arrangement of vertical and horizontal wells so that the bottomhole of a vertical well is positioned above the bottom of a horizontal well at a calculated vertical distance of 3 to 7 m. A heating region is created and it is promoted along the formation parallel to the horizontal wellbore due to swirling the displacing agent into a vertical well. Organize fluid sampling through a horizontal well. According to the invention, a combustible oxidizing mixture, GOS, is used as an agent, for example, a mixture of urea, nitric acid, acetic acid, water and ammonium nitrate, burning under the influence of temperature or a combustion initiator - IG, for example, a composition containing aluminum and chromium oxide, before GOS and IG are fed with production before mixing into the formation through vertical and horizontal wells for ignition and heating of the interwell zone to a temperature of 100-200 ° C, depending on the type of GOS and IG, and establishing a hydrodynamic connection between wells, after which the horizontal well is transferred for fluid production, and the GOS and IS are continued to be fed into the vertical well to maintain combustion and heating of the deposit to the GOS self-combustion temperature - up to 250-300 ° C, after which the IG supply is stopped and the GOS is continued to be pumped to maintain combustion progress parallel to the horizontal wellbore.

The disadvantage of this method is mixing in the composition of products produced using a horizontal well, oil, oil deposits and combustion gases generated behind the combustion front, which are not valuable products. This leads to the fact that the efficiency of the operation of the producing well decreases, and the energy costs of organizing the operation of the producing well increase.

The technical objectives of the invention are:

- achieving higher oil production rates already at the initial stage of development;

- achievement of higher indicators of cumulative oil production;

- increase in depletion of reserves.

The tasks are solved by the method of developing an oil deposit using a horizontal and vertical well system using thermal stress, including drilling and arranging horizontal and vertical wells in such a way that the bottom of the vertical well is placed above the bottom of the horizontal well at a calculated vertical distance of 3 to 7 m, creating an area heating due to injection into wells of GOS and IG for ignition and heating of the inter-well zone to 100-200 ° C, depending on the type of GOS and IG, and the establishment of hydrodynamics connection between wells, transferring a horizontal well for pumping fluid with continued supply of GOS and IG to a vertical well to maintain combustion and heating the reservoir to a temperature of 250-350 ° C - independent GOS combustion, after which IG supply is stopped and the GOS is pumped to continue and advancing combustion along the horizontal wellbore.

What is new is that a horizontal well during construction is equipped with a filter with several zones along the length of the horizontal section, before the pump is lowered into the horizontal well, a liner is inserted that is equipped with thermocouples inside to control the temperature inside the well opposite the filter zones and is capable of only one of zones and closing the filter zones from the bottom to the mouth, and the zone adjacent to the bottom is initially open, after the initiation of combustion with a decrease in the pace in this zone with the maximum achievable during combustion in the conditions of the deposit, up to 85-95 ° C, the production of the pump is stopped by the pump, the liner is turned from the mouth by a predetermined angle, which ensures closure of the bottomhole zone and the opening of the next pump used for further selection of the product after changing it temperatures from the maximum achieved during combustion in the fallow conditions to 85-95 ° C by turning the shank to open this zone, opening the zone next to the bottom, and similarly sequentially opening and closing the zones to the last zone from the bottom of the filter.

Figure 1 schematically shows the wells in their design and for the implementation of the method and the location of the horizontal wellbore moving along the wellbore in the direction from the bottom to the mouth of the combustion front, the vapor zone, the condensation zone of oil and steam and the formation of the rim of hot water and light hydrocarbons, the shaft zone oil with a temperature equal to the initial reservoir, the zone of undeveloped oil, the scorched zone, which are formed in the reservoir when initiating in-situ combustion.

Figure 2 shows a graph of the dependence of the minimum velocity of the combustion front on the thickness of the reservoir, obtained as a result of laboratory studies at a maximum temperature at the combustion front of 260 ° C. (Baibakov N.K., Garushev A.R. Thermal methods for developing oil fields. M: Nedra, 1977. P.168). The graph shows the curves of the change in the minimum velocity of the combustion front at the values of the fuel concentration (kg / m ³ ) in the GOS injected into the oil reservoir: I - 32; II - 24; III - 20; IV - 19.2; V - 18.4.

Figure 3 shows a graph of the temperature inside the horizontal well by zones (see figure 1) for time t ₁ <t ₂ <t ₃ <t ₄ .

Figure 4 shows a section aa of a horizontal well (see figure 1).

Figure 5 shows a section bB horizontal well (see figure 1).

Figure 6 shows a cross-section bb horizontal well (see figure 1).

Figure 7 shows a graph of changes in annual oil production in the case of development of deposits according to the prototype and the claimed method.

On Fig shows a graph of changes in cumulative oil production in the case of the development of deposits according to the prototype and the claimed method.

The proposed method is implemented as follows.

Depending on the geological and physical conditions of reservoir 1 (Fig. 1) and the physicochemical properties of oil in reservoir 1, the injection rate of GOS and IG by calculating technological development indicators, for example, on a digital filtration model, for different values of the length of the horizontal section of the well 2 and the lengths of zones 3, 4, 5 and 6 of the filter 7 of the horizontal section of the well 2 determine the optimal length of the horizontal sections of the well 2 and the optimal length of the zones 3, 4, 5 and 6 of the filter 7 of the horizontal section of the well 2. The optimal length of the zones 3, 4, 5 and 6 filter 7 have inversely related to the thickness of the reservoir 1 and reservoir inversely related to the concentration of fuel in injected in the reservoir 1 CRP (see FIG. 2). With the increase in oil saturation of reservoir 1 (Fig. 1) from minimum values to certain limits, which depend on other parameters of reservoir 1 (the ratio of saturations of oil, gas, water, porosity, permeability) and the rate of injection into reservoir 1 GOS and IG, the optimal length of zones 3, 4, 5 and 6 of filter 7 increases, after reaching this limit with a further increase in oil saturation of reservoir 1, the optimal length of zones 3, 4, 5 and 6 of filter 7 tends to decrease (Sheinman A.B., Malofeev G.E., Sergeev, A.I., Impact on a formation by heat during oil production, Moscow: Nedra, 1969. P.100-102) . The results of laboratory studies to determine the effect on the rate of advance of the combustion front of porosity, initial oil saturation, and initial water saturation of reservoir 1 are given in Table 1 (Bourget J., Surio P., Combarnu M. Thermal methods for increasing oil recovery. / Edited by V.Yu. Filanovsky, E.E. Shpilreina.M .: Nedra, 1988.P.270).

Table 1 Porosity,% Initial oil saturation,% Initial water saturation,% The rate of advancement of the combustion front, cm / h 43.5 47.7 15.9 3.62 40,4 63.5 0 3.81 42.1 25.3 0 3.85 41,4 39.1 0 3.68

Consider, for example, the case of the separation of the horizontal section of the well 2 into four zones 3, 4, 5 and 6 of the perforation of the filter 7.

In the bottom part of the oil reservoir 1, a horizontal well 2 is drilled and equiped. The horizontal well of the horizontal well 2 is divided into zones 3, 4, 5, 6 in the direction from the bottom to the mouth using the filter 7. The angular distance between the openings of the filter 7 in different perforation zones 3 -6 horizontal section of well 2 is a multiple of the whole circle (360 °) divided by the number of zones 3-6. For the case of four perforation zones, the angular distance is 90 °. Inside the filter 7, a shank 8 with holes is installed, which is lowered into a horizontal well 2 at the end of the process pipe string 9, the shank 8 being rigidly connected to the process pipe string 9 using stiffeners 10 and equipped with thermocouples 11, by which temperature is monitored inside the zones 3, 4, 5, 6. The separation of the filter 7 of the horizontal well 2 into zones 3, 4, 5, 6 is ensured by the fact that the angular distance between the holes of the filter 7, corresponding to its perforation zone, is a multiple of a whole circle the number of perforation zones, and the shank 8 has holes in only one row, in all zones 3 (Fig. 5), 4 (Fig. 6), 5, 6 (not shown).

Also in the oil reservoir 1 (Fig. 1), a vertical well 12 is drilled so that its bottom is located above the bottom of the horizontal well 2 at a calculated vertical distance of 3 to 7 m.

In reservoir 1, a heating region is created by injecting GOS (for example, a mixture of urea, nitric acid, acetic acid, water and ammonium nitrate) into wells 2 and 12, the combustion of which begins under the influence of temperature or IG (for example, a composition containing aluminum and oxide chromium). Before the start of production, GOS and IG are mixed with mixing before injection into reservoir 1 along horizontal 2 and vertical 12 wells to ignite and warm the inter-well zone to a temperature of 100-200 ° C (depending on the type of GOS and IG) and establish a hydrodynamic connection between the wells 2 and 12. After that, the horizontal well 2 is transferred to produce well fluid, and the vertical well 12 is continued to be supplied with GOS and IG to maintain combustion and heat the reservoir to the temperature of independent GOS combustion (up to 250-350 ° C). Then, the IG supply to the vertical well 12 is stopped and the GOS injection is continued to maintain and advance the combustion front along the horizontal well 2 well.

According to the results of measuring the reservoir temperature in the vicinity of the horizontal well 2 using thermocouples 11, graphs are plotted (Fig. 3) for the distribution of the reservoir temperature along the horizontal well bore 2 (Fig. 1). An example of such a graph for time instants t ₁ <t ₂ <t ₃ <t _{4 is} shown in Fig. 3, where T ₀ is the initial temperature of the reservoir, T _mountains is the maximum temperature achieved during combustion in reservoir 1 (under the conditions of Mordovo-Karmalsky deposits of the Republic of Tatarstan, the maximum combustion temperature reaches 400-600 ° C).

According to the temperature measurement results of reservoir 1 (Fig. 1) in the vicinity of a horizontal well 2 in zone 3 using thermocouples 11, when the temperature decreases from the value corresponding to the temperature of the formation combustion in the conditions of reservoir 1 to 85-95 ° C, the horizontal well 2 is stopped, turned the process pipe string 9 from the wellhead 2 at an angle sufficient to tightly cover the shank 8 of the holes of the filter 7 in zone 3 (Fig. 5) and open the holes of the filter 7 (Fig. 1) in zone 4 (see Fig. 6), after whereby well 2 (FIG. 1) is launched for product selection tion.

Similarly, during the operation of a horizontal well 2, which selects products from zone 4, using thermocouples 11, the temperature in reservoir 1 in zone 4 is monitored. When the temperature in zone 4 decreases from the value corresponding to the formation combustion temperature to 85-95 ° C horizontal well 2, turn the pipe string 9 from the wellhead 2 by an angle sufficient to tightly cover the shank 8 of the holes of the filter 7 in zone 4 and open the holes of the filter 4 in zone 5 (not shown), after which it is similarly horizontal Azhinov 2 launch for the selection of products. Similarly make the transition to the selection of products from zone 6 (not shown). If there are more zones, they also proceed to the selection of products from subsequent zones.

The nature of the advancement of the combustion front (on the example of the Mordovo-Karmal deposit of the Republic of Tatarstan) along the horizontal wellbore 2 is shown in Fig. 1. When developing a reservoir of high-viscosity oil 1 using thermal action, organized using a vertical well 8, and using a horizontal well 2 as a producing well, a combustion front 13 is formed, which moves along the trunk of a horizontal well 2 in the direction from the mouth to the bottom, and the temperature at the combustion front 13 can reach 400 ° C or more. In front of the combustion front 13, a vapor region 14 is formed, within which a decrease in temperature to 90-204 ° C is observed. In front of the vapor region 14, condensation of oil and steam occurs and a rim of hot water and light hydrocarbons is formed in the region 15. In the region 16, an oil shaft is formed with a temperature equal to the initial formation. In front of the oil shaft of region 16, there is a region of undeveloped oil 17. After passing through the combustion front 13, behind it remains a scorched region 18, in which there are practically no hydrocarbons, but there are combustion gases that are not of industrial value. Combustion gas production together with hydrocarbons leads to a decrease in the total total production of the latter and ultimately reduces the oil recovery coefficient of the deposit. To exclude the production of combustion gases by means of a horizontal well 2, the proposed method provides for closing the perforation intervals of a horizontal well 2 in zones 3, 4, etc., remaining behind the combustion front 13.

The proposed method is implemented as follows:

1. Taking into account the geological and physical conditions of reservoir 1 and the physicochemical properties of oil in reservoir 1, the optimal length of the horizontal section of the well 2 and the optimal length of the perforation zones of the horizontal section of the well 2 are determined by calculating technological indicators of development on a digital filtration model 2. Given the ratio of the optimal length the horizontal section of the well 2 and the optimal length of the perforation zones of the horizontal section of the well 2 determine the number of zones of perforation of the horizontal section of the well 2.

2. In the bottom of the reservoir 1, a horizontal well 2 is drilled and equiped, and its horizontal trunk is divided into perforation zones 3, 4, 5, 6 in the direction from the bottom to the mouth using filter 7, which is ensured by the fact that the angular distance between the holes of the filter 7 in different perforation zones 3-6 of the horizontal section of the well 2 are a multiple of the whole circle (360 °) divided by the number of perforation zones 3-6. For the case of four perforation zones, the angular distance is 90 °. Inside the filter 7, opposite the product sampling zones 3-6, a shank 8 is installed, which is lowered into the well 2 at the end of the pipe string 9 connected to the shank 8 using stiffeners 10. The shank 8 is equipped with thermocouples 11, by which temperature changes are monitored reservoir 1 in the vicinity of horizontal well 2.

3. Also in reservoir 1, a vertical well 12 is drilled, and the bottom of the vertical well 12 is drilled at a calculated distance (from 3 to 7 m vertically) from the bottom of the horizontal well 2.

4. By turning the shank 8 from the wellhead 2, an open filter 7 is installed in the selection zone 3.

5. In the bottom-hole zone of the vertical 12 and horizontal 2 wells along the annular space and the technological column of pipes 9 pump GOS and IG. Due to the reaction, the interwell zone is heated, saturating rocks fluids become more mobile, hydrodynamic connection is established between vertical 12 and horizontal 2 wells. When heating the borehole space to a temperature of 200 ° C and above, the injection of the composition into the horizontal well 2 is stopped. Horizontal well 2 is transferred under the selection of fluid.

6. After warming the near-wellbore zone with a vertical well 12 to a temperature of 250-350 ° C, the injection of IG into the vertical well 12 is stopped, since at this temperature the GOS reaction occurs without the presence of IG.

7. The GOS is continued to be pumped into the vertical well 12, the fluid is taken from the horizontal well 2. Due to the pressure drop and the action of gravitational forces, the advancement of the heating front occurs along horizontal well 2, with the heated oil and reservoir fluid flowing into it and delivered to the surface.

8. In the process of thermal impact on the formation, temperature changes in reservoir 1 in the vicinity of well 2 in zone 3 are controlled by thermocouples 11. Based on the results of the measurements, it is concluded that the temperature in reservoir 1 is distributed along the horizontal wellbore 2. When the temperature decreases in reservoir 1 in the vicinity of the horizontal well 2 in zone 3 from the in-situ combustion temperature to 85-95 ° C, the horizontal well 2 is stopped, the liner 8 is rotated through an angle that provides a tight seal The term filter 7 in the zone of the opening 3 and the filter 7 in Zone 4, and then run on a horizontal borehole 2 product selection.

9. Using thermocouples 11, the temperature is continued to be measured in reservoir 1 in the vicinity of the horizontal well 2 in zone 4. If the temperature in reservoir 1 in the vicinity of the horizontal well 2 in zone 4 decreases from the in-situ combustion temperature to 85-95 ° C, the horizontal well 2 is stopped similarly , the shank 8 is rotated by an angle, which provides a tight seal of the filter 7 in zone 4 and the opening of the filter 7 in zone 5, then a horizontal well 2 is further launched for product selection.

10. Similarly, they proceed to the selection of products from zone 6, and in the case of a larger number of zones for dividing the horizontal wellbore 2, filter 7 selects products from the subsequent zones.

An example of a specific implementation.

To carry out the development of an oil deposit (on the example of the Mordovo-Karmal deposit of the Republic of Tatarstan), according to the claimed method, a site of deposit 1 with the studied geological and physical characteristics, which are given in table 2, was selected.

table 2 Parameter Numerical value Average depth, m 88.5 Type of deposit massive Collector type pore The total area of oil content, thousand m ² 43,750 Average total thickness, m 26.5 Average oil saturated thickness, m 9.5 Porosity, fractions of units 0.24 Oil saturation, fractions of units 0.66 Initial balance reserves of oil, thousand tons 101,3508 Core permeability, μm ² 1,04 Sandiness coefficient, fractions of units 0.97 The coefficient of dissection, the share of units 1.49 Initial formation temperature, ° C 8.0 Initial reservoir pressure, MPa 0.45 Oil viscosity in reservoir conditions, MPa · s 6825.0 The density of oil in reservoir conditions, kg / m ³ 961.0 Volumetric coefficient of oil, fractions of units 1,0 The sulfur content in oil,% 4.7 The paraffin content in oil,% 1,6 The viscosity of water in reservoir conditions, MPa · s 1,53 The density of water in reservoir conditions, kg / m ³ 1006.1 Oil recovery ratio, fractions of units 0.272

Based on the studied geological and physical characteristics, a stationary geological model of reservoir 1 was built in the Irap RMS geological modeling software package. To calculate the technological parameters of development, it was exported to the STARS thermohydrodynamic simulator of the CMG software package. [URL: http: //www.petec.rii/we-suggest/software/cmg.html (accessed 11/27/2013)].

The main parameters of the geological and physical characteristics of reservoir 1 are embedded in a digital filtration model built in the STARS thermohydrodynamic simulator of the CMG software package.

In reservoir 1, horizontal 2 and vertical 12 wells were drilled, and the horizontal well of horizontal well 2, 100 m long, is located in the bottom of reservoir 1, and the bottom of the vertical well is above the bottom of the horizontal well at a calculated vertical distance of 6.5 m.

The following modes of operation of horizontal and vertical wells were established: according to the method, in the injection mode, the wells operate with a bottomhole pressure of 0.8 MPa and the injection volume of the GOS and IG mixture equal to 50 m ³ / day; in the selection mode, the horizontal well operates with a bottomhole pressure of 0.2 MPa

Conducted calculations of technological indicators of the development of reservoir 1 horizontal and vertical wells in the case of the development of reservoir 1 according to the prototype and the claimed method. By calculating the technological indicators of development according to the claimed method, it was determined that the optimal length of the perforation zones into which it is advisable to divide the horizontal wellbore is 25 m. Accordingly, with a horizontal horizontal wellbore length of 100 m, it is divided into four production zones using a filter. The calculations showed that it is optimal to make the transition from one zone of production of a horizontal well to another in the time after the start of development, which are given in Table 3.

Table 3 Transition zones The moment of transition after the start of development 3 → 4 577 days 4 → 5 768 days 5 → 6 855 days

A comparison of the values of the annual and cumulative oil production according to the graphs given in Figs. 7, 8, respectively, shows that when developing the reservoir according to the claimed method, higher rates of maximum annual oil production at the initial stage of development are provided, which ultimately leads to higher values cumulative oil production. As can be seen from the graphs shown in Figs. 7, 8, in the case of developing a deposit according to the claimed method, the maximum annual oil production exceeds the maximum annual oil production corresponding to the development of the prototype by 95.76%, and the cumulative oil production by the end of the 16th the year of development exceeds the value of cumulative oil production in the case of development of a prototype deposit by 31.94%.

The proposed development method allows to increase the maximum annual oil production at the initial stage by about 2 times and increase the depletion of oil reserves for the entire period of operation by 20-25% compared with similar development methods.

Claims (1)

A method of developing an oil deposit using a horizontal and vertical well system using thermal stress, including drilling and arranging horizontal and vertical wells in such a way that the bottom of the vertical well is positioned above the bottom of the horizontal well at a calculated vertical distance of 3 to 7 m, creating a heating area due to injection into the wells of a gas-oxidative mixture of GOS and IG initiator for ignition and heating of the inter-well zone to 100-200 ° С depending on the type of GOS and IG and is set creating a hydrodynamic connection between the wells, transferring the horizontal well to pump fluid with continued supply of GOS and IG to a vertical well to maintain combustion and heating the reservoir to a temperature of 250-350 ° C - independent GOS combustion, after which the IG supply is stopped and the GOS is pumped for maintaining and promoting combustion along the horizontal wellbore, characterized in that the horizontal well during construction is equipped with a filter with several zones along the length of the horizontal section, before by launching the pump into a horizontal well, a shank, equipped with thermocouples inside to control the temperature inside the well opposite the filter zones and configured to rotate the sequential opening of only one of the zones and close the filter zones from the bottom to the mouth, the zone adjacent to the bottom, is initially open, after the initiation of combustion, when the temperature in this zone decreases from the maximum achieved during combustion under the conditions of the reservoir to 85-95 ° C, the selection of products by the pump is stopped, the liner is turned from the mouth at a predetermined angle, ensuring the closure of the bottomhole zone and the opening of the next pump used for further product selection, after changing the temperature in it from the maximum achieved during combustion in the conditions of the deposit, to 85-95 ° C, this zone is closed by turning the shank, opening the next the bottom of the zone, and so similarly sequentially opening and closing the zone to the last zone from the bottom of the filter.

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