RU2822258C1 - Method for development of layer-by-layer-zonal non-uniformv deposit of superviscous oil or bitumen - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: method for development of layer-by-layer-zonal non-uniform deposit of superviscous oil or bitumen includes drilling in productive formation of horizontal injection well and production well located below and parallel to injection well, injection of steam into injection well for heating of productive formation and creation of steam chamber, extraction of product from production well. When the water cut of product reaches 97% and more, the oil flow rate decreases to less than 3 t/day, the geophysical studies are re-interpreted and the core is analysed, presence and depth of strike of low-permeability interlayer is determined with determination of its permeability. When permeability is less than 2 mcm², steam injection is stopped, fluid extraction is continued until temperature of the produced fluid is below 40°C, on both sides relative to horizontal wells vertical wells are drilled in pairs at distance of 15–30 m from shafts of horizontal wells. At that bottomholes of vertical wells are located at distance of 2 m from the bottom of the productive formation. Further, the volume of filled material is calculated and the calculated volume of material is filled in vertical wells from the bottom to level 1 m below the formation roof. After filling of vertical wells, cementing of the remaining interval to the wellhead is performed, after which an injection well is started for steam injection, and a production well – for liquid extraction.

EFFECT: increasing the efficiency of development of layer-by-layer-zonal non-uniform deposit of superviscous oil or bitumen.

1 cl, 2 dwg

Description

The invention relates to the oil production industry and can be used in the development of layer-by-layer-zonal-heterogeneous deposits of high-viscosity and bituminous oil with the presence of a low-permeable interlayer.

There is a known method for developing a layered-zonal-heterogeneous deposit of super-viscous oil or bitumen with the presence of an impermeable interlayer (patent RU No. 2769641, IPC E21B 43/24, publ. 04.04.2022, Bulletin No. 10), including drilling horizontal wells, the horizontal sections of which are carried out in the form of a sinusoid with the intersection of all layers in a multi-layer layered heterogeneous reservoir, and fluid selection from a multilayer layered heterogeneous reservoir, and the viscosity of super-viscous oil or bitumen in reservoir conditions is preliminarily determined, horizontal wells are performed in the form of ascending subhorizontal steam cyclic wells, and the drilling direction is selected in such a way that horizontal sections of wells in the form of a sinusoid in an ascending direction intersect the impermeable interlayer with the formation of sinusoidal steps, while the average level of each subsequent sinusoidal step in absolute elevation is higher than the average level of the previous sinusoidal step by at least 1 m, and the distance between the average levels of two adjacent stages are kept at 150-250 m, depending on the viscosity of super-viscous oil or bitumen, the method of exploitation of the deposit is chosen, with a viscosity of more than 500 mPa*s in reservoir conditions, steam is injected, warming up the super-viscous oil or bitumen, after warming up, liquid is withdrawn, with a viscosity of less 500 mPa*s in reservoir conditions produces fluid selection using a mechanized method.

The disadvantage of this method is the low efficiency of the steam-cyclic method of developing EHV deposits, due to the high steam-oil ratio.

There is also a known method for developing a layer-by-zonal heterogeneous deposit of super-viscous oil or interlayer bitumen (RU patent No. 2761799, IPC E21B 43/24, 7/04, 47/06, publ. 12/13/2021, Bulletin No. 35), including determination in deposits of productive formations separated by low-permeable interlayers, drilling in the lower formation above the oil-water contact of a horizontal well with additional ascending trunks opening the upper formations, the distance between which is determined taking into account the technological capabilities of the drilling equipment for their installation, as well as with the possibility of placing filters with controlled transmission, lowered into a horizontal well before pumping coolant on a pipe string and located opposite additional ascending trunks, as well as packers isolating the annulus of a horizontal well between additional ascending trunks and above filters, determining physical and chemical properties, pumping coolant and sampling products, and after crossing and the exit of additional ascending trunks into the upper productive layer, they are carried out 10-40 m long along the low-productive layer, additional ascending trunks and the main horizontal wellbore are cased, pumping and compressor pipes are lowered into the well with couplings for injection pre-installed opposite the intervals for kicking off the lateral ascending trunks coolant, in which case the coolant is first pumped at an intensity of 90-120 t/day, after which the injection is stopped, the well is left for thermocapillary impregnation for 35-40 days, after thermocapillary impregnation the well is transferred to liquid withdrawal, changes in temperature and water cut of the produced product are monitored, with a decrease temperature of the extracted product to the limit temperature of 30-40°C or an increase in the water cut of the product to 96-99%, the coolant injection is resumed, the coolant is pumped in the volume of the selected liquid, the injection and withdrawal cycles are repeated.

The disadvantage of this method is the small thermal coverage of the formation located above the impermeable interlayer and, as a consequence, low coverage and oil recovery coefficients of high-viscosity and heavy oil deposits; all this does not allow the development of layer-by-zonal heterogeneous deposits of high-viscosity oil or bitumen with sufficient efficiency.

The closest is the method of developing super-viscous oil deposits in a multi-layered heterogeneous reservoir (patent RU No. 2468193, MPK E21B 43/24, publ. November 27, 2012, Bulletin No. 33), including drilling horizontal and vertical injection and production wells, steam injection into the formation, heating of super-viscous oil and its selection from a multi-layered heterogeneous reservoir, while steam injection and product selection are carried out simultaneously, and horizontal wells are performed in the form of a pair of injection and production wells, the horizontal sections of which are placed parallel one above the other in the vertical plane and performed in the form of a sinusoid with the intersection of all layers in a multilayered layered heterogeneous reservoir, then additionally, on different sides relative to the vertical plane of horizontal wells, vertical wells are drilled in pairs in the zones of maximum proximity of the horizontal sections of horizontal wells to the roof and bottom of the multilayered layered heterogeneous reservoir, and the opening areas in vertical injection wells, they are carried out in the lower part of a multilayered layer-by-layer heterogeneous reservoir, and opening sections in vertical production wells are carried out in the upper part of a multilayered layered-inhomogeneous reservoir, while the opening areas of vertical injection wells must be performed at a distance of at least 5 m to the lower horizontal section, and in vertical production wells, the opening areas must be at least half the thickness of the multilayer layered inhomogeneous reservoir, the multilayer layered inhomogeneous reservoir is heated by pumping steam into both wells to form a steam chamber, the interwell zone of the multilayered inhomogeneous reservoir is heated with a decrease viscosity of super-viscous oil, steam is injected into the upper horizontal injection well and production is taken from the lower production horizontal well, then steam is injected simultaneously into the horizontal injection well and into vertical injection wells in the zones of maximum proximity of sections of horizontal wells to the base of a multi-layered layer-by-layer heterogeneous reservoir, and product selection is carried out simultaneously from a horizontal production well and from vertical production wells located in zones of maximum approximation of horizontal sections to the roof of a multi-layered layer-by-layer heterogeneous reservoir, while monitoring the technological parameters of the multi-layer layer-by-layer heterogeneous reservoir and wells in the process of product selection, periodically determining salinity of the produced water, analyze the effect of changes in the salinity of the produced water on the uniform heating of the steam chamber and, taking into account the change in the mineralization of the produced water, carry out uniform heating of the steam chamber by adjusting the steam injection mode or withdrawing well production until a stable value of salinity of the produced water is achieved with simultaneous injection steam and product selection.

The disadvantages of this method are the insufficient efficiency of the method associated with the small coverage of the thermal effect of the formation and low coverage coefficients of the super-viscous oil deposit, as well as the high costs of construction (lowering and casing of pipe strings) and arrangement of vertical wells for steam injection, the risk of leakage in vertical wells and, as a consequence, steam breakthrough through the behind-the-casing flows.

The technical objectives are to increase the efficiency of development of layer-by-zonal heterogeneous deposits of super-viscous oil or bitumen with the presence of a low-permeable interlayer by increasing thermal coverage and improving hydrodynamic communication, as well as increasing the oil recovery factor.

Technical problems are solved by a method for developing a layer-by-zonal heterogeneous deposit of super-viscous oil or bitumen, including drilling a horizontal injection well in the productive formation and a production well located below and parallel to the injection well, pumping steam into the injection well to warm up the productive formation and create a steam chamber, extraction products from a production well.

What is new is that when the water cut of the product reaches 97% and above, the oil flow rate decreases to less than 3 tons/day, a reinterpretation of geophysical research and core analysis is carried out, the presence and strike depth of a low-permeable interlayer are determined, and its permeability is determined, when the permeability decreases to less than 2 μm ² steam injection is stopped, liquid extraction is continued until the temperature of the produced liquid drops below 40 °C, vertical wells are drilled in pairs on both sides of the horizontal wells at a distance of 15-30 m from the horizontal wells, while the bottoms of the vertical wells are located at a distance of 2 m from the bottom productive formation, then the volume of filled material is calculated using the formula:

V=π*R²*H,

where V is the volume of material poured to fill the well;

π is a constant value equal to 3.14;

R is the internal diameter of the vertical well;

H is the height from the bottom of the vertical well to a level 1 m below the roof of the vertical well;

the calculated volume of material is poured into vertical wells from the bottom to a level 1 m below the roof of the formation, after filling the vertical wells, the remaining interval is cemented to the wellhead, after which the injection well is launched for steam injection, and the production well for liquid extraction.

Also new is that a sand-gravel mixture or crushed stone or gravel is used as the backfill material.

In fig. Figure 1 shows a profile of a well layout for a method for developing a layer-by-layer-zonal-heterogeneous deposit of super-viscous oil or bitumen with the presence of a low-permeability interlayer.

In fig. Figure 2 shows a top view of a method for developing a layer-by-layer-zonal-heterogeneous deposit of super-viscous oil or bitumen with the presence of a low-permeability interlayer.

The method for developing a layer-by-zonal heterogeneous deposit of super-viscous oil or bitumen is carried out as follows.

A layered-zonal-heterogeneous deposit of super-viscous oil or bitumen in a multilayered layered-zonal-heterogeneous reservoir 1 (Fig. 1) is a productive formation consisting of several layers (layers), heterogeneous in their filtration-capacitive properties and permeability (in Fig. 1 is shown conditionally), there is a low-permeability interlayer 2 (Fig. 1).

A pair of horizontal injection 3 and production wells 4 is drilled, located below and parallel to the injection 3 well. Steam is pumped into the injection well 3 to heat the productive formation and create a steam chamber, and products are taken from the production well 4.

When the water cut of the product reaches 97% or higher, and the oil flow rate decreases to less than 3 tons/day, a reinterpretation of geophysical studies and analysis of the core of appraisal wells is carried out. The presence and depth of the low-permeable interlayer are determined and its permeability is determined. When the permeability of the low-permeable interlayer decreases to less than 2 μm ^2, steam injection into the injection well 3 is stopped, work is carried out to cool the pair of horizontal injection 3 and production wells 4, and fluid extraction is continued until the temperature of the produced fluid drops below 40 °C.

After this, on both sides of the relatively horizontal injection 3 and production 4 wells, vertical wells are drilled in pairs, for example, 5, 5', 5", 5"', 5"", 5""' (Fig. 2) at a distance of 15-30 m from the horizontal injection 3 and production 4 wells, while the bottoms of vertical wells 5, 5', 5", 5"', 5"", 5""' (Fig. 1) are located at a distance of 2 m from the bottom of the productive formation .

Next, the volume of filled material is calculated using the formula:

V=π*R²*H,

where V is the volume of material poured to fill the well,

π is a constant value equal to 3.14,

R is the internal diameter of the vertical well,

H - height from the bottom of a vertical well to a level 1 m below the roof of a vertical well, m

Fill vertical wells 5, 5', 5", 5"', 5"", 5""' with the calculated volume of backfilled material from the bottom to a level 1 m below the roof of the formation. A sand-gravel mixture of ASG or crushed stone or gravel is used as the backfill material.

Sand-gravel mixture ASG is a mixture containing gravel and sand with grain sizes from 1 mm to 70 mm according to GOST 23735-2014.

Crushed stone and gravel are inorganic granular bulk material with grains with a grain size of 5 mm or more, obtained by crushing rocks, gravel and boulders, incidentally mined overburden and host rocks or substandard waste from mining ore processing enterprises, according to GOST 8267-93.

The use of ASG or crushed stone or gravel leads to the same results.

After filling the vertical wells 5, 5', 5", 5"', 5"", 5""' with the calculated volume of backfilled material, the remaining interval is cemented to the wellhead, after which the injection well 3 is launched for steam injection, and the production well 4 - for fluid selection.

Drilling vertical wells on both sides of horizontal wells makes it possible to create highly permeable channels, improve hydrodynamic communication, and subsequently increase thermal coverage by expanding the coverage of the steam-gravity method. This increases the efficiency of developing a layered-zonally heterogeneous deposit of super-viscous oil or bitumen with the presence of a low-permeability interlayer, and increases the oil recovery factor.

Example of a specific application.

In the developed Arkhangelsk deposit of super-viscous oil with a productive reservoir located at a depth of 170 m, with an average effective oil-saturated thickness of 12 m, reservoir temperature 8°C, pressure 0.4 MPa, oil saturation 66%, porosity 30%, permeability 2.5 μm ² , with a density of super-viscous oil in reservoir conditions of 944 kg/m ³ , a viscosity of 11821 mPa s, they constructed a horizontal injection well with a length of 1309 m and a production well with a length of 1364 m in the productive formation.

Steam was injected to warm up the productive formation and create a steam chamber. At the initial stage of development (the first 3 months of development), a high water cut of the produced product (97%) and low oil flow rates (2.9 tons/day) were observed. Conducted reinterpretation of geophysical surveys and analysis of cores from appraisal wells. We determined the location of one low-permeability interlayer at a depth of 175 m, and revealed a decrease in permeability to 1.34 µm ² .

Steam injection was stopped, liquid was withdrawn until the produced liquid cooled to a temperature of 39 °C. We drilled 6 vertical wells 5, 5', 5", 5"', 5"", 5""' on both sides of the horizontal wells, with vertical well 5 located at a distance of 15 m from the horizontal, 5' - at a distance of 18 m , 5" - at a distance of 30 m, 5"' - at a distance of 23 m, 5"" - at a distance of 28 m, 5"" - at a distance of 21 m so that they are located opposite the "heel" zone, the middle and "toe" zone of horizontal wells. We calculated the volume filled with ASG for each well: 5 - 0.5 m ³ (at R - 0.151 m, H - 8 m), 5' - 0.71 m ³ (at R - 0.151 m, H - 10 m) , 5" - 0.85 m ³ (at R – 0.151 m, H - 12 m), 5"' - 0.93 m ³ (at R – 0.151 m, H - 13 m), 5"" - 0, 78 m ³ (at R - 0.151 m, H - 11 m), 5"" - 0.71 m ³ (at R - 0.151 m, H - 10 m). ASG was poured into vertical wells from the bottom to a level 1 m below the roof of the formation. After filling the estimated volume of ASG, Active II-160KM cement was pumped to the wellhead and the cement was lifted to the surface. Next, we launched an injection well for steam injection, and a production well for liquid extraction.

As a result of using this method, the oil flow rate increased to 10 tons/day, and the water cut of the product decreased to 94%.

Claims (8)

1. A method for developing a layered-zonal-heterogeneous deposit of super-viscous oil or bitumen, including drilling a horizontal injection well and a production well in a productive formation located below and parallel to the injection well, pumping steam into the injection well to warm up the productive formation and create a steam chamber, product selection from a production well, characterized in that when the water cut of the product reaches 97% or higher, the oil flow rate decreases to less than 3 tons/day, a reinterpretation of geophysical studies and core analysis is carried out, the presence and strike depth of a low-permeable interlayer are determined, and its permeability is determined; when the permeability decreases to less than 2 µm ² steam injection is stopped, liquid extraction is continued until the temperature of the produced liquid drops below 40°C, vertical wells are drilled in pairs on both sides of horizontal wells at a distance of 15-30 m from the horizontal wells, while the bottoms of vertical wells are located at a distance of 2 m from the base of the productive formation, then the volume of backfilled material is calculated using the formula: V=π*R ² *H, where V is the volume of material poured to fill the well, m ³ ; π is a constant value equal to 3.14; R is the internal diameter of the vertical well, m; H is the height from the bottom of the vertical well to a level 1 m below the roof of the vertical well, m; the calculated volume of material is poured into vertical wells from the bottom to a level 1 m below the roof of the formation, after filling the vertical wells, the remaining interval is cemented to the wellhead, after which the injection well is launched for steam injection, and the production well for liquid extraction. 2. A method for developing a layer-by-zonal heterogeneous deposit of super-viscous oil or bitumen according to claim 1, characterized in that a sand-gravel mixture, or crushed stone, or gravel is used as the backfill material.