RU2652245C1 - Method for developing the bituminous oil deposit - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry. Method for developing bituminous oil deposit comprises construction of pairs of horizontal upper and lower wells, horizontal sections of which are placed one above the other in the vertical plane of the reservoir, equipped with a flow string, which allow simultaneous injection of the coolant and selection of products, heating of the reservoir with creation of a steam chamber, selection of products through the lower horizontal well along the flow string. Before the development begins, one or several vertical wells are drilled in any known grid in the area of the proposed development of the oil deposit. Geophysical investigations or coring studies in them determine the viscosity along the vertical section of the formation, determine the average viscosity of the formation, identify two zones, first of which is located above the horizontal boundary, below which the viscosity exceeds the average by no more than 2 times, in the second zone the viscosity exceeds the average by more than 3 times. For construction of wells a site is chosen, said site is a site where the distance between the zones does not exceed 15 m, in the first zone, but not closer than 8 m from the roof of the formation and not more than 1 m from the water-oil contact or the bottom of the formation, pairs of upper and lower horizontal wells are constructed. If the lower well is drilled at a level of 4 m or higher than the water-oil contact level, in the second zone between the pairs of horizontal upper and lower wells, not less than 1 m above the water-oil contact or the outsole of the formation, a sealing horizontal well is drilled as low as possible, but not below than 15 m from the level of the corresponding horizontal lower wells. Sealing horizontal well is operated in steam cycle mode until the hydrodynamic coupling is established with the pairs of horizontal wells, after which it is transferred to permanent oil production.

EFFECT: reduced thermal energy costs, increased selection of recoverable reserves, increased oil production in the initial period of development, reduced risk of the horizontal production well entering the formations with a high viscosity of oil, increased coverage factor.

1 cl, 2 dwg, 1 ex

Description

The invention relates to the oil industry and may find application in the development of tar deposits.

There is a method of developing a reservoir of high viscosity oil during thermal exposure (patent RU No. 2425969, IPC ЕВВ 43/24, published in Bull. No. 22 of 08/10/2011), including the construction of a producing well with a horizontal exposed section in the reservoir, the construction of an injection well with a horizontal uncovered section located above a similar section of a production well in the same formation, pumping coolant into an injection well and taking production of a formation from a production well in which horizontal wells are drilled in parallel in opposite directions with the placement of the face opposite the entrance of a horizontal nearby well into the reservoir.

The disadvantages of the method are the technological complexity of its implementation, in particular, the difficulty of navigation when drilling the second wellbore (the risk of crossing horizontal wellbores), as well as the cost of construction due to the need to build two drilling sites. In addition, the lack of research on oil viscosity increases the likelihood of increasing the oil-steam ratio and reducing the efficiency of the wells due to the location of the horizontal wellbore in the zone with an increased viscosity of the reservoir oil.

There is also known a method of developing deposits of high viscosity oil (patent RU No. 2379494, IPC EV 43/24, publ. 01/20/2010, bull. No. 2), including the use of a pair of horizontal injection and production wells. The horizontal sections of these wells are placed parallel to one another in the vertical plane of the reservoir. The wells are equipped with a tubing string (tubing), which allows simultaneous injection of heat transfer fluid and production selection, injection of heat transfer fluid, heating of the productive formation with the creation of a steam chamber, production selection through the production well and control of the technological parameters of the formation and well. According to the invention, the ends of the tubing strings are located at the opposite ends of the conventionally horizontal section of the wells. Warming up the productive formation begins with steam injection into both wells, heats the inter-well zone of the formation, and lowers the viscosity of high-viscosity oil. By pumping a heat carrier propagating to the upper part of the reservoir, a steam chamber is created. The size of the steam chamber is increased, in the process of product selection periodically, 2-3 times a week, the mineralization of the water taken along the way is determined. The effect of changes in the mineralization of the water taken along the way on the uniformity of heating the steam chamber is analyzed. Taking into account the changes in the mineralization of the water taken along the way, the steam chamber is uniformly heated by adjusting the coolant injection mode or selecting production wells to achieve a stable mineralization value of the water taken along the way.

The disadvantage of this method is the lack of research on the viscosity of oil, which increases the likelihood of increasing the steam-oil ratio and reducing the efficiency of the wells due to the location of the horizontal well of the producing well in the zone with an increased viscosity of the reservoir oil.

The closest in technical essence and the achieved result is a method of developing a field of highly viscous oils or bitumen (patent RU No. 2531963, IPC ЕВВ 43/24, published in Bull. No. 30 dated 10.27.2014), including the construction of pairs of horizontal mining and injection wells, as well as vertical observation wells, pumping coolant through injection wells with heating the reservoir and creating a steam chamber, product selection due to steam gravity drainage through production wells importance and control over the state of the steam chamber, while the development of a super-viscous oil field is carried out with the current size of the steam chamber being controlled by changing the volume of coolant pumped into injection wells and taking fluid from production wells with control of the volume of the steam chamber, while observation wells are opened below the lower horizontal production wells at least 0.5 m, but above the level of water-oil contact (VNK) by 0.5-1 m, build an additional well between adjacent pairs of horizontal wells, and if the area of the steam chamber in the reservoir is less than the distance between the pairs of production and injection wells, then an additional horizontal well is built, if it is larger, then a vertical one, and additional wells are opened at least 0.5 m below the lower horizontal production well, but not lower than the level of KNK by more than 0.5 m, they heat up additional wells with a coolant until a thermohydrodynamic connection with nearby pairs of horizontal wells is created, followed by by transferring to the selection of products to ensure a symmetrical and uniform distribution of the steam chamber around pairs of horizontal wells, superheated steam or steam with a hydrocarbon solvent, or steam with an inert gas, is used as a heat carrier.

The disadvantages of the method are the lack of studies on the viscosity of oil, which increases the likelihood of increasing the steam-oil ratio and reducing the efficiency of the wells due to the location of the horizontal well of the producing well in the zone with an increased viscosity of the reservoir oil, as well as the lack of determination of reserves below horizontal producing wells.

The technical objectives of the method of developing a tar oil deposit are to reduce the cost of thermal energy, increase the rate of extraction of recoverable reserves, as well as save money on initial heating, increase oil production in the initial period of development and reduce the risk of a horizontal production well getting into reservoirs with high oil viscosity due to research in viscosity and well placement in the required interval of the reservoir, also in viscosity, increase in coverage coefficient due to the involvement of previously unused running out of stocks.

Technical problems are solved by the method of developing a bituminous oil deposit, including the construction of pairs of horizontal upper and lower wells, the horizontal sections of which are placed parallel to each other in the vertical plane of the reservoir and are equipped with tubing strings that allow the coolant to be pumped and the product to be taken, and the inter-well zone of the reservoir the creation of a steam chamber, the selection of products through the lower well through the tubing.

What’s new is that before the start of development, one or several vertical wells are drilled using any well-known grid in the area of the proposed development of the oil reservoir, geophysical or core studies in them determine the viscosity along the vertical section of the formation, the average viscosity of the formation, there are two zones, the first of which is located above the horizontal boundary, below which the viscosity exceeds the average by no more than 2 times, in the second zone, the viscosity exceeds the average by more than 3 times, knock out For the construction of wells, a section is constructed where the distance between the zones does not exceed 15 m, is higher than the first zone, but not closer than 8 m from the top of the formation and not closer than 1 m from the oil well or the bottom of the formation; pairs of upper and lower horizontal wells are constructed if the lower well was drilled at a level of 4 m or higher than the level of the oil well, then in the second zone between pairs of horizontal upper and lower wells no lower than 1 m above the level of the oil well or bottom of the formation, a horizontal horizontal well is drilled as low as possible, but not lower than 15 m from the level of the corresponding horizontal lower wells zhin, wherein the horizontal sealing hole operated in cyclic steam mode to establish flow connection with pairs of horizontal wells, after which it is transferred under a constant oil.

In FIG. 1 shows a diagram of the implementation of the method.

In FIG. 2 is a graph of the viscosity of tar oil in a formation versus the distance from the formation roof.

A method for developing a tar oil deposit includes preliminary study of reservoir 1 (Fig. 1) of a geophysical or core study aimed at measuring the viscosity parameter along the vertical wellbore (not shown in Fig. 1) previously drilled or drilled specifically for determining viscosity and properties of formation 1 according to any known grid in the area of the proposed development of the oil reservoir. When strata 1 with a vertically heterogeneous viscosity structure is identified, the arithmetic mean or average dynamic viscosity (average viscosity) weighted by thickness or volume is determined from the data obtained from geophysical or core studies. With an increase in the viscosity of bituminous oil, zones 3 and 4 are distinguished to the sole 2 of formation 1: the first of which (zone 3) is located above the conditional horizontal boundary 5, below which the viscosity exceeds the average by no more than 2 times, in the second zone (zone 4) the viscosity exceeds the average by more than 3 times (below border 6). A section is selected for the construction of wells where the distance between zones 3 and 4 does not exceed 15 m, is higher than the first zone 3, but not closer than 8 m from the top of the formation 7 and not closer than 1 m from the oil-water (water-bitumen) contact of the VNK (VBK) 8, which is distinguished in the presence of a water-saturated area at the sole 2 of the formation 1 or the sole of the formation 2. A pair of upper 9, 9 'and lower 10, 10' horizontal wells are built. The horizontal sections of the wells 9, 9 'and 10, 10' are placed one above the other in the vertical plane of the reservoir 1 above the VNK (VBK) 8. Steam injection through the tubing (not shown in Fig. 1) into the horizontal upper 9, 9 'and lower 10, 10 'wells achieve heating of the inter-well zone of the reservoir 1 and obtain a hydrodynamic connection between the wells 9, 9' and 10, 10 '. Then, wells 9, 9 'and 10, 10' are left for thermocapillary impregnation to lower the temperature in the bottomhole zone of the lower horizontal well 10, 10 'to a value that allows the operation of downhole equipment. After that, steam is pumped into the upper horizontal well 9, 9 ', transferring the lower horizontal well 10, 10' under production. If the lower 10, 10 'well was drilled at a level of 4 m or higher than the level of VNK (VBC) 8, then in the second zone 4 between pairs of horizontal upper 9, 9' and lower 10, 10 'wells not lower than 1 m above the level of VNK ( VBC) 8 or the soles of formation 2 are drilling a horizontal horizontal seal 11 as low as possible, but not lower than 15 m from the level of the corresponding horizontal lower wells. The horizontal sealing well 11 is operated in a cyclic mode until a hydrodynamic connection is established with the pairs of horizontal wells 9, 9 'and 10, 10', after which it is transferred under continuous oil production.

An example of a specific implementation.

The proposed method for the development of bituminous oil deposits was considered at the Nizhne-Karmal deposit with the following geological and physical characteristics:

- average total formation thickness of 37.1 m;

- oil saturated formation thickness of 35.5 m;

- the depth of the formation (to the roof) 190 m;

- the value of the initial reservoir pressure of 0.73 MPa;

- initial reservoir temperature of 8 ° C;

- the density of oil in reservoir conditions of 0.98 t / m ³ ;

- coefficient of average dynamic viscosity of oil in reservoir conditions 51270 mPa⋅s;

- coefficient of dynamic viscosity of water in reservoir conditions 1.6 MPa⋅s;

- the value of the average core permeability in the reservoir of 2.1 μm ² ;

- the value of the average core porosity in the reservoir 0.31 d.

In oil-saturated formation 1 (Fig. 1), core studies determined the change in oil viscosity depending on the vertical distance from the roof 7 of formation 1 (I (Fig. 2) - viscosity according to core studies, II - a graph of viscosity changes depending on distance over vertical from the top of the formation, III is the viscosity limit below which the viscosity is 1.5 times higher than the average, IV is the viscosity border, below which the viscosity is 4 times higher than the average). Then, the weighted average thickness viscosity over the reservoir was determined, it amounted to 51270 mPa⋅s. Boundaries 5 and 6 were determined (Fig. 1), below which the viscosity exceeds the average by 1.5 and 4 times, respectively (vertical distances 23.5 m and 29.5 m, respectively, from the roof 7 of formation 1). Thus, the first zone 3 in viscosity is located above 23.5 m, if we consider the distance to the roof of the formation 7, the second zone 4 in viscosity is located below 29.5 m, if we consider the distance to the roof of the formation 7. The upper boundary of the second zone 4 by viscosity is located at a distance of 6 m above the level of VNK (VBK) 8 (respectively, the level of VNK (VBK) 8 at a distance of 35.5 m from the roof 7 of formation 1). At a distance of 13 m from the level of VNK (VBK) 8 (22.5 m from the roof of layer 7 of formation 1), the lower horizontal wells 10 and 10 'with lengths of horizontal sections of 600 m were located. Above the lower horizontal wells 10 and 10' at a distance of 5 m upper horizontal wells 9 and 9 'also with lengths of horizontal sections of 600 m (17.5 m from the roof 7 of formation 1). Between pairs of horizontal wells 9, 9 'and 10, 10' parallel to the boreholes of these wells at a distance of 4 m (31.5 m from the roof 7 of formation 1) from VNK (VBK) 8, a horizontal sealing well was drilled 11. After arranging the upper and lower horizontal wells 9, 9 'and 10, 10' steam was injected into them with a temperature of 191 ° C and a dryness of 0.9 units. (discharge pressure - 1.2 MPa). After the calculated steam volume (20.6 thousand tons) was pumped, the 9, 9 'and 10, 10' wells were stopped and left for thermocapillary impregnation for 27 days. Simultaneously with wells 9, 9 'and 10, 10', 4.7 thousand tons of steam were pumped into well 11 and left for thermocapillary impregnation also for 27 days. Upon reaching a temperature of 110 ° C in the lower horizontal wells 10 and 10 ', the upper horizontal wells 9 and 9' were transferred for steam injection, and the lower horizontal wells 10 and 10 'were transferred for oil production. For the first 1.5 years, horizontal well 11 operated as a steam cycle (injection cycle according to the estimated steam volume of 4.7 thousand tons - production cycle until the water cut of production is equal to 98.5%). Then, when a hydrodynamic connection is reached between the horizontal well 11 and the pairs of wells 9, 9 'and 10, 10', the well 11 is transferred to a constant oil production.

The parameters of the presented method, as well as the prototype method at the facility with the same geological and physical characteristics for various operating conditions were considered. From the obtained calculations, the advantage of the method over the prototype was also revealed: a decrease in the time to reach the industrial influx of oil (above 15 tons / day) by 1.5 years (2 years according to the prototype, 0.5 years according to the presented method) (oil production increased accordingly initial period of time), an increase in the rate of production from current recoverable reserves by 23.5% for the entire development period (7.65% according to the prototype, 10% according to the proposed method), an increase in the economic efficiency of wells by 13%, a decrease in specific injection steam per 1 ton of oil produced (4.0 t / t - according to the prototype, 3.5 t / t - according to the proposed method), which allows to reduce the cost of thermal energy.

The proposed development method is simple to use and significantly reduces the cost of thermal energy, increases the rate of extraction of recoverable reserves, saves money on initial heating, increases oil production in the initial development period and reduces the risk of horizontal production wells getting into reservoirs with high oil viscosity, and also increases the coverage factor due to the involvement of previously unoccupied in the development of reserves by a sealing well.

Claims (1)

A method of developing a tar oil deposit, including the construction of pairs of horizontal upper and lower wells, the horizontal sections of which are placed one above the other in the vertical plane of the reservoir, equipped with a tubing tubing string that allows simultaneous injection of coolant and product selection, heating of the reservoir with the creation steam chamber, product selection through the lower horizontal well by tubing, characterized in that before the start of development one sludge is drilled several vertical wells on any known grid in the area of the proposed development of the oil reservoir, geophysical or core studies in them determine the viscosity of the vertical section of the formation, determine the average viscosity of the formation, distinguish two zones, the first of which is located above the horizontal border, below which the viscosity exceeds the average by no more than 2 times, in the second zone, the viscosity exceeds the average by more than 3 times, choose a section for well construction where the distance I’m waiting for zones not exceeding 15 m, in the first zone, but not closer than 8 m from the top of the formation and not closer than 1 m from the oil-water contact of the oil-water complex or the bottom of the formation, pairs of upper and lower horizontal wells are built if the lower well has been drilled at a level of 4 m or higher level of the oil well, then in the second zone between the pairs of horizontal upper and lower wells not less than 1 m above the level of the oil well or bottom of the formation, a horizontal horizontal well is drilled as low as possible, but not lower than 15 m from the level of the corresponding horizontal lower well, with a horizontal horizontal well zhinu operated in cyclic steam mode to establish flow connection with pairs of horizontal wells, after which it is transferred under a constant oil.

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