CN110644957A

CN110644957A - Novel method for improving development effect of super heavy oil edge water reservoir

Info

Publication number: CN110644957A
Application number: CN201910966028.3A
Authority: CN
Inventors: 王学忠
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-10-10
Filing date: 2019-10-10
Publication date: 2020-01-03

Abstract

The invention provides a novel method for improving the development effect of an ultra-heavy oil edge water reservoir, which comprises the following steps: performing oil reservoir flooding type diagnosis, and selecting a proper oil reservoir; drilling a ciphered well on the first-line oil well row closest to the side water, and implementing a high-dose nitrogen foam water pressing cone on the first-line old oil well and the new well; drilling a new well in the preferable residual oil enrichment area in the oil reservoir, forming a steam-driven well pattern together with the old well, and converting into steam drive; normal steam huff and puff production is carried out on two wings of the oil reservoir, and the main part of the oil reservoir is shielded for normal production by shunting the invaded edge water; drilling a new well in the water body, and simultaneously reducing the formation pressure of the water body and the water supply amount of side water by using an old well through water recovery to slow down the adverse effect of the side water on the main body part of the oil reservoir; according to production needs, a new round of high-dose nitrogen foam water pressing cone is developed for the first-line well. The method can recover the reserve and the yield lost due to flooding, bring huge economic benefits, and is very beneficial to improving the utilization rate of petroleum resources and ensuring the national energy safety.

Description

Novel method for improving development effect of super heavy oil edge water reservoir

Technical Field

The invention relates to the technical field of oilfield development, in particular to a novel method for improving the development effect of an ultra-heavy oil edge water reservoir.

Background

The data shows that in the global conventional crude oil reserves, the reserves of the heavy oil, the super heavy oil and the asphalt account for about 70 percent; in our country, the thick oil reserves account for over 50%. Therefore, heavy oil will be an important place for future oil and gas development. China's heavy oil reserves are in the seventh place in the world, resources are widely distributed, and more than 70 heavy oil fields are found in 12 basins.At present, the development and utilization rate of thickened oil in China is only 8 percent, and the main reason is that the technical process and the like are not in place. How to innovate and form a characteristic thickened oil exploitation technology, effectively improve the national thickened oil exploitation capability, and have important significance for guaranteeing the national energy safety. The typical edge water super heavy oil reservoirs such as a Liaohe eosin oil field eosin 175 big Ling river oil layer, a Liaohe jin 45 oil field, a Shengli single temple oil field single 2 Shahe street oil layers, a Shengli spring wind oil field row 601-20 Shawan oil layers, a Shengli grass bridge oil field and a Jilin sleeve oil field face a common problem that large-area water logging, storage capacity and yield loss are serious due to edge water invasion in a steam throughput depressurization exploitation process. For example, in the last 90 s of the century, crude oil in the Shengli bridge oil field has viscosity of 20000mPa & s, shallow burial, high sandstone permeability, active side water and geological reserve of 7000 multiplied by 10⁴t. In the multi-cycle throughput depressurization exploitation process, the side water invasion is intensified year by year, and the calculated annual water flooding reserve reaches more than million tons. After several years, the whole oil extraction mine is shut in. The thick oil is most afraid of water in thermal recovery. The harm of the side water to the development of the thickened oil mainly comes from the fact that a large amount of heat is absorbed by the water, the viscosity reduction of the crude oil is influenced, and the thermal recovery effect is reduced. Therefore, active measures are required to prevent the invasion of boundary water into the oil reservoir, and the steam utilization rate is improved by inhibiting the water invasion.

The field of domestic and foreign oil exploitation is more abundant in water plugging technology of single side water heavy oil wells, such as nitrogen foam, temperature-sensitive gel, jelly, polymer, steam drive and the like, but the whole oil deposit after being taken in and out for multiple times is incapable of being pushed by side water due to depressurization exploitation, and after the first-line oil well is quickly flooded by water, the front edge of a water body is more easily pushed along the bottom of an oil layer and gradually invades a second-line well due to the large density and small viscosity of the water, so that the high water content of a large oil well is caused to be shut in, and the waste reserves are very much. The traditional water plugging method has the limitations that firstly, the cost is high, and the requirement of large-scale application is difficult to meet; secondly, the water is mostly blocked once or permanently, and the second and third water blocking is difficult to be carried out in the well; thirdly, the radius of water plugging action is very limited, and the water plugging device has no substantial effect on a large-range area between wells, and a new channel can be opened up by edge water to continue water logging. Therefore, a new method for improving the development effect of the ultra-heavy oil edge water reservoir is invented, and the technical problems are solved.

Disclosure of Invention

The invention aims to provide a revolutionary novel method for improving the development effect of the ultra-heavy oil edge water reservoir by drilling the encryption well in a low-position and strong-water-flooded area.

The object of the invention can be achieved by the following technical measures: the novel method for improving the development effect of the super heavy oil edge water reservoir comprises the following steps: step 1, diagnosing the flooding type of an oil reservoir, and selecting a proper oil reservoir; step 2, drilling a ciphered well on the first-line oil well row closest to the edge water, and implementing a high-dose nitrogen foam water pressing cone on the first-line old oil well and the new well; step 3, drilling a new well in the preferable residual oil enrichment area in the oil reservoir, forming a steam-driven well pattern together with the old well, and converting into steam drive; step 4, normal steam huff and puff production is carried out on two wings of the oil reservoir, and the main part of the oil reservoir is shielded for normal production by shunting the invaded edge water; step 5, drilling a new well in the water body, and reducing the formation pressure of the water body and the water supply amount of side water by using an old well through water recovery to slow down the adverse effect of the side water on the main part of the oil reservoir; and 6, developing a new round of high-dose nitrogen foam water pressing cone for the first-line well according to production requirements.

The object of the invention can also be achieved by the following technical measures:

in the step 1, the selected oil reservoir is mainly flooded by the ultra-heavy oil with water, the residual oil is enriched, the development potential is large, and the side water is in the low-structure part.

The step 1 comprises the following steps:

1a, testing the viscosity of crude oil and the rheological property of the crude oil by sampling and testing to realize the type of the crude oil, wherein the crude oil belongs to super heavy oil;

2a, performing comparative analysis on original oil saturation, logging data, actual drilling data and seismic data to implement oil-water relationship and ensure that the high part is oil and the low part is water;

3a, carrying out reservoir sensitivity analysis to ensure that the method is suitable for steam thermal recovery;

4a, belonging to loose sandstone reservoirs by implementing reservoir burial depth, reservoir lithology, porosity, permeability, reservoir thickness and collecting sand sample implemented reservoir types;

5a, fully knowing the enrichment condition of the residual oil through various means such as numerical simulation, physical simulation, dynamic monitoring and dynamic analysis, and finding out a residual oil enrichment area;

6a, knowing whether flooding occurs or not through indexes of single well yield, water content and oil-gas ratio;

7a, knowing the flooding degree through the indexes of single-well yield, water content and oil-gas ratio;

8a, judging whether the flooding is rapid flooding or not according to the oil extraction speed, the extraction degree and the water content;

9a, mastering the change trend of flooding development through numerical simulation, physical simulation, oil reservoir parameters, water content change and oil reservoir pressure field change;

10a, implementing the geometric form of flooding by seismic data interpretation, well logging data interpretation, actual drilling condition and dynamic change development;

and 11a, calculating the volume of the water body through seismic data interpretation, well logging data interpretation, actual drilling conditions and development dynamic change.

In step 2, drilling a ciphered well on the first-line oil well row closest to the edge water, implementing a high-dose nitrogen foam water pressing cone on the first-line old oil well and the new well, closing all the second-line oil wells, relieving water logging and recovering the formation pressure; the first defense line of the three-dimensional water plugging well pattern is constructed by the first line well and the second line well together.

The step 2 comprises the following steps:

1b, analyzing and judging whether the original well spacing is reasonable or not through development data;

2b, judging whether the original well spacing is reasonable or not through regional development effect evaluation;

3b, analyzing and judging whether the original well spacing is reasonable or not through the effect of a production increasing measure;

4b, drilling an encryption well on the first-line oil well row closest to the edge water;

5b, judging whether the heavy oil thermal recovery well spacing is reasonable;

6b, demonstrating by an oil reservoir engineering method and an empirical formula, and determining the number of drilled wells and the specific well spacing;

7b, implementing a high-dose nitrogen foam water pressing cone on the first-line old oil well and the new well, and pressing side water invasion in the processes of treating steam overburden, selectively plugging, deeply adjusting profile and supplementing formation energy;

8b, ensuring that the high-dose nitrogen foam water pressing cone is effectively developed;

9b, carrying out effective well selection;

10b, determining the using amount of the plugging agent through an empirical formula and the oil layer fracture pressure;

11b, monitoring and ensuring the quality of the plugging agent through processes of metering and sampling and testing the plugging agent;

12b, closing all the second-line oil wells, relieving flooding and recovering the formation pressure.

The step 3 comprises the following steps:

1c, demonstrating the well pattern and the well spacing of the encrypted wells through an oil reservoir engineering method, an empirical formula and numerical simulation;

2c, adopting intermittent steam drive to reduce the steam consumption;

3c, ensuring the steam injection quality through the analysis and the test of the steam injection ratio, the steam injection dryness at the well head, the steam injection dryness at the well bottom, the single well liquid amount of the oil well and the sand-containing sampling;

4c, injecting nitrogen in the steam flooding process, which is not only beneficial to the heat insulation of the oil layer, but also can reduce the steam consumption and is beneficial to expanding the steam sweep range.

The step 5 comprises the following steps:

1e, carefully depicting the geometric form of the water body through three-dimensional seismic data interpretation and actual drilling data, calculating the volume of the water body by referring to a volumetric method for calculating the crude oil reserves, and replacing the values of the relevant parameters of the oil with the relevant parameters of the water;

2e, well selection is conducted through hydrodynamic system analysis, reservoir comparison and reservoir physical property explanation;

3e, ensuring that the formation water can meet the clean water condition of the steam injection boiler through technical improvement;

and 4e, realizing water resource recycling through technical matching.

In step 6, a new round of high-dose nitrogen foam water pressing cone is developed for the first-line well according to production needs, and the operation is repeated once and again as long as the effect is good.

The step 6 comprises the following steps:

1f, carrying out correct evaluation on the implementation effect of the previous round through oil well yield, water content change, a three-line four-zone method and input-output ratio analysis;

2f, judging whether a new round of high-dose nitrogen foam water pressing cone is carried out or not according to the evaluation result;

3f, repeating the steps repeatedly as long as the effect is good;

4f, increasing the oil production speed by arranging a large pump and increasing production parameters in the oil reservoir, and seizing oil and producing oil as early as possible within the effective period of water plugging of the first-line well and the second-line well;

and 5f, making comprehensive judgment through evaluation of flooding hazard and evaluation of treatment effect.

The invention discloses a novel method for improving the development effect of an ultra-heavy oil side-water reservoir, which aims at the problems of large-area water logging and serious reserve and yield loss caused by side water invasion in the steam huff-puff depressurization exploitation process of the ultra-heavy oil side-water reservoir. The method is characterized in that a row of new wells are drilled in a direction perpendicular to a water flooding direction, the new wells and old wells form a water blocking dam together, and then nitrogen foam is injected into the water blocking dam in a large amount to press a water cone. Drilling and extracting wells in water bodies is also quite promising. Compared with the traditional well point water plugging method, the invention provides a method for drilling and encrypting a new well in a strong water flooded area, and water plugging can be performed for multiple times as required. The reason why the water plugging is not performed on the basis of the original well network is mainly that the original well distance is large and the edge water is difficult to block to advance. The invention jumps from the traditional thinking fixed mode of drilling the encryption well at the high part of the structure and the residual oil enrichment area, but actively drills the encryption well at the low part of the structure and the strong water flooding area, which is not easy to think and is not easy to do. Petroleum is non-renewable fossil energy, and the petroleum resource occupied by all people in China is very deficient, 4 hundred million tons of crude oil needs to be imported every year, and the external dependence degree exceeds 70 percent. The invention can recover the reserve and yield lost by flooding, bring huge economic benefit and is very beneficial to improving the utilization rate of petroleum resources and ensuring the national energy safety.

Drawings

FIG. 1 is a flow chart of an embodiment of the novel method of improving the development of an ultra heavy oil side water reservoir of the present invention;

FIG. 2 is a graph illustrating a plurality of reservoir parameter distributions at a time node after a plurality of steam huffs and puffs in a block, in accordance with an embodiment of the present invention;

FIG. 3 is a schematic illustration of water development, well distribution, and water propulsion after multiple steam stimulation rounds for a block in accordance with an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating the method of removing 601-20 blocks to improve the development effect of the shallow extra-heavy oil edge water reservoir in an embodiment of the present invention;

FIG. 5 is a schematic illustration of rows 601-20 of sand bodies in accordance with an embodiment of the present invention;

FIG. 6 is a schematic top view of a row 601-20 sand bodies in accordance with an embodiment of the present invention;

FIG. 7 is a diagram of rows 601-20 of flooded panels in accordance with an embodiment of the present invention;

FIG. 8 is a diagram of a development curve for blocks 601-20 according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of an embodiment of the present invention with 601-20 steam flood patterns;

FIG. 10 is a schematic diagram of relationship curves and index predictions for water content and recovery for 601-20 steam flooding in accordance with an embodiment of the present invention.

Detailed Description

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

As shown in fig. 1, fig. 1 is a flow chart of the novel method for improving the development effect of the ultra heavy oil side water reservoir of the present invention.

And step 101, performing reservoir water flooding type diagnosis, wherein the selected reservoir mainly comprises super heavy oil side water flooding, residual oil is enriched, the development potential is large, and side water is in a low-structure part. The method comprises the following specific steps:

firstly, the crude oil type is determined by sampling and testing the viscosity of the crude oil and testing the rheological property of the crude oil, and the crude oil is required to belong to super heavy oil. The method meets the requirements that the crude oil viscosity of an oil layer is more than 20000mPa & s under the original condition, the crude oil basically has no flow capacity under the original stratum condition, and steam huff-puff thermal recovery is required.

And secondly, the oil-water relationship is implemented through the contrastive analysis of the original oil saturation, logging data, actual drilling data and seismic data, and the oil-water relationship is ensured to be oil at the high part and water at the low part. In the process of storing the super-thick oil, because the density of the crude oil is less than that of water, the crude oil is gathered at a higher part of a structure to form an oil layer under the action of gravity differentiation, and a lower part of the crude oil is an oil-water transition zone and even completely becomes a water layer (water body).

Thirdly, reservoir sensitivity analysis is carried out, and steam thermal recovery is guaranteed to be suitable. If the water sensitivity is strong, the clay expands when meeting water (steam), so that the permeability of a reservoir is greatly reduced, and the oil reservoir is not suitable for application of the method.

Fourthly, the method is to collect the sand sample to realize the type of the oil reservoir through the implementation of the oil reservoir burial depth, the reservoir lithology, the porosity, the permeability and the oil reservoir thickness, and belongs to the loose sandstone oil reservoir. The oil reservoir burial depth is required to be less than 700m, the reservoir porosity is more than 30%, the permeability is more than 1000mD, and the oil reservoir thickness is more than 4 m. The reason for this is that the reservoir physical property is better, the well has better connectivity, and can provide a flow channel for water, nitrogen and steam. And the heat loss of the shaft is small, so that the steam can keep high dryness and enough heat in the oil layer, and the thermal recovery effect is realized.

And fifthly, the enrichment condition of the residual oil is fully known through various means such as numerical simulation, physical simulation, dynamic monitoring, dynamic analysis and the like. The method is important to find a residual oil enrichment area, ensure the relative enrichment of residual oil and provide a resource foundation for the potential excavation of the residual oil, and ensure that oil can be extracted.

Sixthly, whether flooding occurs or not is known through indexes such as single well yield, water content, oil-gas ratio and the like. Steam huff and puff belongs to depressurization exploitation, and as the formation pressure continuously decreases, edge water invasion is inevitably caused, so that water flooding is caused. The phenomenon of flooding is different from the common general knowledge of life that people walk from high to low by keeping water and stopping water, and the flooding is a seepage process from the low part to the high part, and the process is generally considered to be irreversible.

And seventhly, knowing the flooding degree through indexes such as single well yield, water content, oil-gas ratio and the like. If the degree of flooding is not serious, people do not need to hurt money to treat the flooding. In severe flooding, the water content of the flooded oil field rises rapidly, the oil yield decreases rapidly, even drops to 0, and the oil field is forced to shut down. Flooding is an inherent phenomenon in oil field development, particularly great harm is caused to the steam throughput of the super heavy oil, and mainly shows that the development effect is obviously poor after the super heavy oil side water reservoir is flooded, the yield of a single well is very low (for example, the daily oil production of the single well is lower than 2t/d), the oil-gas ratio is very low (for example, the cycle oil-gas ratio is lower than 0.2, that is, only 2t of oil can be produced by injecting 10t of steam, the development benefit is very poor), the water content is very high (generally higher than 95%), on the other hand, the oil resource production degree is very low, and the underground residual oil is still very enriched.

And eighthly, judging whether the flooding is rapid flooding or not according to the oil extraction speed, the extraction degree and the water content. If the method is slow gradual and uniform flooding and the production degree exceeds 20 percent, the water content is generally high, and the method is not suitable for the invention. The invention is more suitable for a rapid water flooding type to ensure that the residual oil is still enriched, and has greater development potential.

And ninthly, mastering the change trend of the flooding development through numerical simulation, physical simulation, oil reservoir parameters, water content change and oil reservoir pressure field change. In order to clear the point, the original geological modeling and numerical simulation work is carried out, the original oil deposit geological model, numerical model and physical model need to be updated and perfected, a new round of numerical simulation and physical simulation is carried out, the water flooding development trend is predicted, and the water flooding condition can be known by means of oil deposit parameters, water content change and oil layer pressure field change without carrying out the geological modeling and numerical simulation work (fig. 2 and fig. 3).

And tenthly, the water logging geometrical form is realized through seismic data interpretation, well logging data interpretation, actual drilling condition and dynamic change development. Ensuring that the oil reservoir is controlled by the structure, is in a geometric shape of the oil reservoir at a microstructure high part and edge water at a microstructure low part, and has a certain structure inclination angle; under the action of oil-water gravity differentiation, a relatively clear oil-water interface is formed; the side water flooding is the main flooding type of the block, and the side water invasion direction is accurately judged.

Eleven, calculating the volume of the water body through seismic data interpretation, well logging data interpretation, actual drilling conditions and dynamic change development. Ensure that the water volume is larger, but is not suitable to exceed 6 times of the oil reservoir volume (in a range that can be treated, otherwise the treatment cost is too high and is not cost-effective).

And 102, drilling an encryption well on the well row of the first-line oil well closest to the edge water, implementing a high-dose nitrogen foam water pressing cone on the first-line old oil well and the new well, closing all the second-line oil wells, relieving flooding and recovering the formation pressure. The first defense line of the three-dimensional water plugging well pattern is constructed by the first line well and the second line well together.

The method comprises the following specific steps:

firstly, whether the original well spacing is reasonable is judged through development data analysis. Due to concerns about low single well reserves and cross-well steam channeling, super heavy steam stimulation intervals are typically large (over 120m) to ensure that the steam stimulation period is economically uncompromised. After 601-20 oil wells are arranged and steam is steamed for multiple times (15 steaming periods), the water content is 93.9%, the oil extraction speed is 0.45%, the average oil-steam ratio is 0.26, and 40% of the oil wells stop production due to water logging, so that the danger of complete shut-down of the oil wells after further water logging is faced. Compared with the peak yield, the yield is reduced by 90%, the geological reserve extraction degree is only 16%, 84% of reserve is reserved underground and cannot be developed, the steam throughput heating radius is only 30m, and the unreasonable original well spacing is verified.

And secondly, judging whether the original well spacing is reasonable or not through regional development effect evaluation. According to the distance from the edge water to the edge water, 601-20 oil wells are divided into a first-line well (about 200m away from the edge water), a second-line well (about 500m away from the edge water) and an oil well inside the oil deposit, the development effect difference is obvious (table 1 and figure 4), the water content of the first-line well, the second-line well and the oil well inside the oil deposit is reduced in sequence, the accumulated oil of a single well is increased in sequence, and the difference is obvious. Wherein, the oil-water transition zone near the low part of the structure is firstly flooded by water, and the edge water is vertical to the structure line and gradually pushes towards the high part of the structure. The first-line well is close to the side water, so that the development effect is poor, and the situation that the original well distance is unreasonable and the flooding risk possibly brought by the side water when a well pattern is deployed and developed is not enough is shown.

TABLE 1 Classification statistical table for 601-20 development effects in spring wind oil field

Thirdly, whether the original well spacing is reasonable is judged through the effect analysis of the production increasing measures. For example, after the first-line well of 601-20 rows is flooded, the plugging and adjusting measures are difficult to take effect (Table 2). The reason why the water plugging is not carried out on the basis of the original well network is mainly that the original well distance is large, the edge water propulsion is difficult to block, many oil fields have tragic training in the aspect, the water plugging workload and the cost investment are large, and the effect is poor.

TABLE 2 statistics of nitrogen foam profile control effect of 601-20 first-line wells in spring wind oilfield

Fourthly, drilling a ciphered well on the first-line oil well row closest to the edge water. Therefore, the method is a reference for a previous vehicle with poor side water plugging effect caused by overlarge distance between the original wells.

Fifthly, the invention provides a new method for judging whether the well spacing for thermal recovery of the heavy oil is reasonable, and if the new well spacing can exceed 35% in the steam huff-puff and steam flooding stages, the new well spacing is a scientific and reasonable well spacing. This aspect is well-trained, and therefore, it is necessary to drill a tight well on the first-line well row closest to the edge water on the basis of the original well network, with the well spacing of about 30 m.

And sixthly, the number of drilled wells and the specific well spacing are determined by demonstrating an oil reservoir engineering method and an empirical formula.

And seventhly, implementing a high-dose nitrogen foam water pressing cone on the first-line old oil well and the new well, and pressing side water invasion in the processes of treating steam overburden, selectively plugging, deeply adjusting profile and supplementing stratum energy.

Eighthly, the large-dose nitrogen foam water pressing cone is ensured to be effectively developed through equipment introduction and personnel training. Nitrogen gas is not affectedThe material has the characteristics of source limitation, no toxicity and harm, low dissolved gas-oil ratio, large elastic expansion coefficient, low heat conductivity coefficient and the like. The nitrogen foam water pressing cone belongs to mature technology at present, for example, before the grass 13-flat 9-well measure (the 4 th week of steam stimulation): production is carried out for 144 days, oil 1033t, daily liquid 29.3t, daily oil 1.9t and water content 93.9%. Measure construction: foaming agent 5t + Nitrogen 67200Nm³And gas injection quantity 1501 t. After the measures are carried out, the peak value daily oil production is 12t/d, the water content is 57%, the formation pressure is improved by 2MPa, the effect is taken for 634 days, and the oil production is 5660 t. In the early stage of development of spring breeze oil field, nitrogen foam measure is implemented 30 well times, and has 24 well times of effect, and the cumulative oil increment is 2.1X 10⁴t。

Ninthly, a new effective well selection method is invented. The nitrogen foam water pressing cone well selection consensus in the industry is that the steam huff-puff cycle does not exceed the 6 th cycle, the distance from an oil-water boundary is more than 200m, the viscosity of underground crude oil is less than 40000mPa & s, and an oil reservoir with edge water is not developed basically. The nitrogen foam water pressing cone is adopted in the invention, the oil increasing effect of the well is not pursued, but the effect of constructing the water blocking dam is achieved, the well selection condition is broken through, and the constraints of the well selection conditions such as the number of times of huffing and puff, the distance from an oil-water boundary, the viscosity of underground crude oil and the like are avoided. The well can be enclosed as long as the well is favorable for improving the whole water plugging effect.

And tenthly, determining the dosage of the plugging agent by an empirical formula and the fracture pressure of the oil layer. According to the calculation formula (1), the dosage of the plugging agent is designed by comprehensively considering the production condition, the thickness of an oil layer and production measures after plugging. The nitrogen dosage can be referred to the nitrogen injection pressure, and the nitrogen injection pressure is not suitable to exceed the reservoir fracture pressure, or the nitrogen dosage can be referred to the nitrogen injection pressure until the nitrogen injection in the current round can not be performed. And recommending that 8 ten thousand standard squares of nitrogen is injected into a single well for one time and 5t of foaming agent is injected into the well.

P＝3.14r²hφc (1)

In the formula, the amount of P-blocking agent, m³；

r-radius at the outer edge of the formation, m;

h-oil layer thickness, m;

phi-oil layer porosity,%;

c-dosage coefficient, decimal.

And eleventh, the quality of the plugging agent is ensured by monitoring the processes of meter metering, plugging agent sampling assay and the like. The nitrogen with low cost and high purity is produced by a nitrogen making vehicle, the purity is more than 96 percent, and 600 standard prescriptions of nitrogen are produced per hour. The foaming agent is resistant to high temperature of 300 ℃ and has surface tension lower than 32 mN/m. The dosage strictly executes the scheme design, and ensures sufficient and good injection.

And twelfth, closing all the second-line oil wells to relieve flooding and restore the formation pressure. The unheated super-thick oil is in the shape of natural asphalt and is a good water shutoff agent. And under the condition of small formation pressure drop, the power of side water invasion is weakened.

Through the work, the first defense line of the three-dimensional water plugging well pattern is constructed by the first line well and the second line well together.

103, drilling a new well in the preferable residual oil enrichment area in the oil reservoir, and converting the new well into steam flooding together with the old well.

The method comprises the following specific steps:

firstly, the well pattern and the well distance of the encrypted well are demonstrated through an oil reservoir engineering method, an empirical formula and numerical simulation. Drilling of the encrypted well is a prerequisite for the development of steam flooding, which is a scientific judgment based on the poor effect of the past steam flooding.

The traditional concept considers that steam flooding is a technology for replacing steam huff-puff, so that consideration is reasonable, after all, steam huff-puff depressurization is more favorable for large-scale steam injection into a formation, however, contrary to expectations, depressurization after multiple rounds of steam huff-puff induces severe flooding, and the steam huff-puff scheme is inexhaustible. The oil-steam ratio of steam flooding is low, and the development of steam flooding in a large-range water flooding area is completely in the dream of people. To avoid this, it is necessary to perform steam flooding early in the well that has not yet suffered severe flooding. In fact, the steam flooding technology appears earlier than steam huff and puff, the oil recovery mechanisms of the two technologies are different, the requirements on the well pattern well spacing are different, and the steam flooding carried out by the well pattern well spacing of the steam huff and puff is obviously not suitable, which is an important principle ignored by many people in the industry.

And secondly, intermittent steam drive is adopted to reduce the steam consumption. The shut-in time should not exceed 50 days in general to ensure that the subsurface temperature field is maintained at a higher temperature to effectively reduce the viscosity of the crude oil. The intermittent steam drive is demonstrated and optimized through an oil reservoir engineering method, an empirical formula and numerical simulation, and thought constraints and extensive practice caused by the traditional concept need to be overcome, so that the practice is true.

Thirdly, the steam injection quality is ensured by analyzing and testing the extraction-injection ratio, the steam injection dryness at the well mouth, the steam injection dryness at the well bottom, the liquid amount of a single well of the oil well and the sand content. We have achieved accurate monitoring of bottom hole temperature, pressure, steam quality, crude oil saturation. The extraction-injection ratio is required to be more than 1.2, the steam injection dryness at the well mouth is more than 90 percent, and the steam injection dryness at the well bottom is more than 60 percent. The single well liquid amount of the oil well is not lower than 20t/d, and the single well liquid amount is not higher than 50t/d in order to avoid exciting the stratum to produce sand.

Fourthly, injecting nitrogen in the steam flooding process. The heat insulation and preservation of the stratum are facilitated, the energy of the stratum is supplemented, the pressure of the stratum is recovered in time, and nitrogen is distributed at the middle upper part of the oil layer to reduce the steam heat loss; nitrogen, which acts as an "insulating blanket", collects at the top of the reservoir, preventing heat loss to the upper rock.

Thus, a second line of defense against water flooding is constructed by recovering formation pressure through steam flooding.

And step 104, normal steam throughput production of two wings of the oil reservoir is carried out, and the main part of the oil reservoir is shielded to carry out normal production by shunting the invaded edge water. Due to the streaming phenomenon of the edge water, the effect of the two-line water flooding is affected even if the water body is too large (particularly more than 10), which is a supplementary measure for the first three steps.

And 105, drilling a new well in the water body, and simultaneously utilizing the old well to reduce the formation pressure of the water body and the water supply amount of the edge water through water production so as to slow down the adverse effect of the edge water on the main part of the oil reservoir (if flooding is regarded as flood, the method is equivalent to opening up a flood discharge area). And the produced water can be used as a clear water source of a steam boiler (although the produced water has the defect of high mineralization degree, the resource utilization treatment station of the produced water of the first oil field in China is built in the spring wind oil field by introducing Israel equipment for purifying seawater, which is completely realized).

The method comprises the following specific steps:

firstly, the geometric form of the water body is seriously depicted through three-dimensional seismic data interpretation and actual drilling data, the volume of the water body is calculated by referring to a volumetric method for calculating the crude oil reserves, and the values of the relevant parameters of the oil are replaced by the relevant parameters of the water. The water volume of the heavy oil reservoir is limited under the control of the reservoir environment. Different from precision disciplines such as mathematics, physics, chemistry and the like, some indexes of oil field development do not need to be particularly precise. For example, the volume of a body of water is a variable and an estimate may be made within a reasonable range, and may not be particularly accurate, but may be helpful in making a correct determination.

And secondly, well selection is explained through hydrodynamic system analysis, reservoir comparison and reservoir physical property. The water recovery well has several conditions, and the water layer and the oil reservoir belong to the same reservoir layer and the same oil-water system and have good connectivity with each other. The water layer has large thickness, high porosity and permeability, abundant water production capacity, and daily water production capacity of more than 100m per well³。

Thirdly, the formation water can meet the clean water condition of the steam injection boiler through technical improvement. The high-density suspension clarifier is developed aiming at the high silicon content in the produced water and the corrosion and scaling of fluorine, sulfur and iron ions, and the formation water is used as the clean water of the steam injection boiler.

Fourthly, the water resource recycling is realized through technical matching. The problems of high temperature (70 ℃), high mineralization degree (18126mg/L) and high silicon dioxide content (180mg/L) of hot produced water are solved through low-temperature multi-effect mechanical compression evaporation, the cyclic utilization of water resources is realized, the economic benefit is improved, the environmental protection requirement is met, and the assisted oilfield becomes a green enterprise.

And step 106, developing a new round of high-dose nitrogen foam water pressing cone for the first-line well according to production needs, and repeating the steps as long as the effect is good. Thereby maximally recovering the reserve and yield loss caused by flooding and greatly improving the utilization rate of the heavy oil resources.

The method comprises the following specific steps:

firstly, the correct evaluation is made on the implementation effect of the previous round through the analysis of the oil well yield, the water content change, a three-line four-zone method of the victory oil field and the input-output ratio. In order to actively and effectively deal with the continuously low international oil price, a three-wire four-area economic operation model of an oil field enterprise is innovatively established by applying the marginal analysis theory of micro-economics; dividing 3 cost lines of running cost, operation cost and complete cost according to the sensitivity of the cost to the yield; the evaluation objects of the oil-water well single well, the development unit, the development block, the oil extraction management area, the oil production plant, the oil field and the like are divided into 4 benefit areas with high profit efficiency, effective margin, low increment efficiency and invalid operation. And developing benefit grading, implementing classification strategy, guiding low-cost development of oil field enterprises, and promoting benefit production and loss reduction profit of the oil field enterprises.

And secondly, judging whether a new round of high-dose nitrogen foam water pressing cone is carried out or not according to the evaluation result.

Thirdly, the method is repeated repeatedly as long as the effect is good. Thereby maximally recovering the reserve and yield loss caused by flooding and greatly improving the utilization rate of the heavy oil resources.

And fourthly, increasing the oil production speed by arranging a large pump and increasing production parameters inside the oil reservoir, and seizing oil and producing oil as early as possible within the effective period of water plugging of the first-line well and the second-line well.

And fifthly, comprehensive judgment is made through evaluation of flooding hazard and evaluation of treatment effect, so that the application strength of the invention is improved. The invention can be used globally, and the problem is seen globally, which is the key point for the large-scale application and the substantial effect of the invention, and the invention is a Chinese patent medicine, not a headache doctor and a foot pain doctor. After all, flooding is an irreversible process, and can only be slowed down, but cannot be stopped or eradicated. Meanwhile, if no benefit is obtained, the technology cannot fall to the ground. Because petroleum is a non-renewable precious resource, the water flooding is treated inevitably and slowly, and the cost for treating the water flooding can be recovered as soon as possible only by intensive exploitation in the oil deposit (main body part), so that the maximum comprehensive benefit is ensured, and the invention is also the original purpose.

The following is a specific embodiment to which the present invention is applied.

601-20 sand bay group rows of the Xianguan basin west spring wind oil field belong to a thin shallow super heavy oil edge water sandstone oil reservoir (figure 5), and the oil-bearing area is 6.11km²Geological reserve 691 × 10⁴t. The structure is high in the north, high in the south and low in the north,the dip angle is 1-2 degrees, and the buried depth is 360-550 m (figure 6). The lithology of the reservoir is brown oil-rich sandstone, the median of the particle size is 0.23mm, the average porosity is 34%, the permeability is 900-2850 mD, the thickness of a single sand body is only 2-6 m, the reservoir has weak speed sensitivity, medium weak water sensitivity, weak acid sensitivity and no alkali sensitivity, and the medium salt sensitivity critical mineralization degree is 10690 mg/L. The reservoir rock wettability is hydrophilic. In a normal temperature and pressure system, the oil layer temperature is 26 ℃ under the original condition, and the oil layer pressure is 4 MPa. The viscosity of crude oil under the original condition of an oil layer is 24800-42000 mPa & s, and the salinity of formation water is 25000-45000 mg/L. Crude oil under the oil layer condition is pseudoplastic fluid, and the seepage capability is poor; the formation pressure is low, and the difficulty in establishing an effective production differential pressure is high; the oil layer is thin, the steam is easy to overflow and dissipate, and the heat utilization efficiency is low. Aiming at the problems of low formation pressure and small production pressure difference caused by shallow oil reservoir burial depth, the formation energy is supplemented by injecting high-elasticity expansion energy gas; aiming at the problems of low vertical well productivity and large stratum heat loss caused by thin sand body thickness, the horizontal well is applied to enlarge oil drainage area and inject inert gas to insulate heat and preserve heat; the problems of high viscosity and poor fluidity of the crude oil in the stratum are solved by adopting a mode of injecting steam and viscosity reducing agent for reducing viscosity in a synergic manner. Adopting the technology for pilot production in 2010 (the length of a horizontal well section is 200m, 7t of the soluble viscosity reducing agent is injected into a single well for the time, 6 ten thousands of standard of nitrogen and 1600t of steam), and at the end of the year, 6 wells are opened, 25t of daily oil is produced, and the water content is 82.1%; in the production capacity construction process of 2011-2012, a part of well zones are found to have high water content, so that the number of production wells put into production in 2012 is the largest, and only 70% of the number of wells designed by the original scheme, 95% of total wells in 7 months in 2012, 71% of open wells, 410t of daily produced oil and 75.5% of water are completed, and the peak value of the daily produced oil in the block appears in 6 months in 2013, 560t of daily produced oil and 65.1% of water. And then, the high water content shut-in wells caused by water logging are gradually increased (figure 7), and by 7 months in 2019, 65 wells are opened, the daily oil yield is 76t, the water content is 93.9%, the oil extraction speed is 0.45%, and the geological reserve extraction degree is 16% (figure 8). The high water cut-in 39 causes the reservoir which can not be effectively used to exceed 200 ten thousand tons, and the oil well is in danger of being shut down completely after further water logging (figure 4 and table 1). The first-line well row 601-22 only produces 396t of accumulated oil, the row 601-28 only produces 28t of accumulated oil, the second-line well row 601-20 only produces 9913t of accumulated oil and the row 601-23 only produces 9862t of accumulated oil, and the destructive property of boundary water to development can be seenIs very large. Analysis shows that the length of the oil-water transition zone reaches 2km, the volume of the water body is 5 times of the volume of the oil reservoir, and the energy of the edge water body is large. The fluid seepage capability is inversely proportional to the viscosity of the fluid, the viscosity of the degassed crude oil at 50 ℃ of the block is 1700-4000 mPa & s, the viscosity of water is only 0.4mPa & s, the seepage capability of the water is obviously higher than that of the crude oil, and water flooding is easily formed. After multiple rounds of steam huff and puff, the reservoir formation pressure is reduced to 2.5MPa, the water pressure is as high as 5.6MPa, and a pressure drop funnel from the water to the reservoir is very obvious and becomes a warrior in excessive water flooding. The block adopts hole-filling layer-changing 7 well times, blocking 1 well time, chemical water plugging 4 well times, microbial oil extraction 6 well times and 2 well group steam flooding in sequence, and the yield-increasing effect is not obvious. There seems to be no better solution other than shut-in of a row after a row. The invention is used for this purpose.

1. And (5) strengthening reservoir research. The method is expected to realize that the residual oil is more, fully knows the enrichment condition of the residual oil through various means, obtains the scientific conclusion of local enrichment of the residual oil, and provides a resource foundation for the potential excavation of the residual oil, which is the successful premise of the method; the reservoir has good physical properties, and the wells have good connectivity, and can provide flow channels for water, nitrogen and steam; the oil reservoir is controlled by the structure, is in a geometric form that the oil reservoir is at a high part of the microstructure and the edge water is at a low part of the microstructure, and has a certain structural inclination angle; and accurately judging the side water invasion direction.

2. On the basis of the original well pattern, 10 encrypted wells are drilled on the first line of oil well row closest to the side water, the well spacing is about 30m, and a first defense line of the three-dimensional water plugging well pattern is constructed. And (3) implementing a high-dose nitrogen foam water pressing cone on the first-line well (including old oil wells and newly drilled encryption wells) closest to the edge water, and pressing the edge water invasion while supplementing the formation energy. The nitrogen dosage can be referred to the nitrogen injection pressure, and the nitrogen injection pressure is not suitable to exceed the reservoir fracture pressure, or the nitrogen dosage can be referred to the nitrogen injection pressure until the nitrogen injection in the current round can not be performed. The nitrogen is injected into a single well for 8 ten thousand standard times, and the foaming agent is 5 t. And closing all the second-line oil wells to recover the formation pressure.

3. And (4) drilling a new well with 30 mouths in the oil deposit in the preferable residual oil enrichment area, and converting the new well into steam drive together with the old well. By adopting a reverse nine-point well pattern (figure 9), namely one steam injection well, corresponding to 8 oil production wells, the predicted recovery rate can reach 38 percent (figure 10). And (3) injecting nitrogen, fully supplementing the formation energy, recovering the formation pressure in time, and constructing a second defense line for suppressing water flooding at the edge.

4. Normal steam huff and puff production is carried out on two wings of the oil reservoir, and the main part of the oil reservoir is shielded to carry out normal production by shunting the invaded edge water.

5. 7 wells are drilled in the water body, 3 old wells are utilized, and the adverse effect of side water on the main part of the oil reservoir is relieved by water recovery.

6. According to production needs, a new round of large-dose nitrogen foam flooding is carried out on the first-line well, and the method is repeated once and again as long as the method is effective. After the comprehensive implementation of the invention, the reserve capacity of recovering the flooding loss is estimated to be 150 ten thousand tons, the oil is increased by 6 ten thousand tons every year, and the new output value is increased by 2 hundred million yuan. The method brings huge economic benefits by recovering the reserve volume and the yield of the flooding loss, and is very beneficial to improving the utilization rate of petroleum resources and ensuring the national energy safety.

The new method for improving the development effect of the super heavy oil edge water reservoir treats edge water invasion by drilling a new well, and simultaneously gives full play to the traditional technical advantages of the nitrogen foam water pressing cone, so that the success on points is converted into the three-dimensional water plugging advantage on the whole line, the whole surface and the whole volume, and the method is a revolution to the traditional water plugging mode. It requires a large investment of capital at a time to pursue strategic wins rather than a success or failure tied to a single well. The traditional thinking fixed mode of drilling the encryption well at the high-structure part and the residual oil enrichment area is skipped, and the encryption well is actively drilled at the low-structure part and the strong water flooding area, so that the encryption well is not easy to think and is not easy to realize. The application effect depends on three factors, oil can be recovered, the whole row of wells are linked, and the well production is not allowed during the water plugging period. Therefore, three-dimensional water plugging can be realized in space and can be repeated in time, nitrogen with low cost and high purity can be produced by the nitrogen making vehicle, the water plugging cost is low, multiple rounds of water plugging can be carried out as required, the nitrogen consumption is very flexible, and long-acting water plugging can be realized. Most people will not favor drilling infill wells in heavily flooded areas, which is just the point of the invention.

Claims

1. The novel method for improving the development effect of the super heavy oil edge water reservoir is characterized by comprising the following steps of:

step 1, diagnosing the flooding type of an oil reservoir, and selecting a proper oil reservoir;

step 2, drilling a ciphered well on the first-line oil well row closest to the edge water, and implementing a high-dose nitrogen foam water pressing cone on the first-line old oil well and the new well;

step 3, drilling a new well in the preferable residual oil enrichment area in the oil reservoir, forming a steam-driven well pattern together with the old well, and converting into steam drive;

step 4, normal steam huff and puff production is carried out on two wings of the oil reservoir, and the main part of the oil reservoir is shielded for normal production by shunting the invaded edge water;

step 5, drilling a new well in the water body, and reducing the formation pressure of the water body and the water supply amount of side water by using an old well through water recovery to slow down the adverse effect of the side water on the main part of the oil reservoir;

and 6, developing a new round of high-dose nitrogen foam water pressing cone for the first-line well according to production requirements.

2. The new method for improving the development effect of the ultra-heavy oil side-water reservoir as claimed in claim 1, wherein in step 1, the selected reservoir is mainly flooded with the ultra-heavy oil side-water, the remaining oil is enriched, the development potential is large, and the side water is in the low-structure part.

3. The new method for improving the development effect of the ultra heavy oil side water reservoir according to claim 2, wherein the step 1 comprises:

4. The new method for improving the development effect of the ultra-heavy oil edge water reservoir as claimed in claim 1, wherein in step 2, a infill well is drilled on the first line of oil well row closest to the edge water, a large-dose nitrogen foam water pressing cone is applied to the first line of old oil well and the new well, the second line of oil well is completely shut down, the water logging is relieved, and the formation pressure is recovered; the first defense line of the three-dimensional water plugging well pattern is constructed by the first line well and the second line well together.

5. The new method for improving the development effect of the ultra heavy oil side water reservoir according to claim 4, wherein the step 2 comprises:

5b, judging whether the heavy oil thermal recovery well spacing is reasonable;

9b, carrying out effective well selection;

6. The new method for improving the development effect of the ultra heavy oil side water reservoir according to claim 1, wherein the step 3 comprises:

2c, adopting intermittent steam drive to reduce the steam consumption;

and 4c, injecting nitrogen in the steam flooding process.

7. The new method for improving the development effect of the ultra heavy oil side water reservoir according to claim 1, wherein the step 5 comprises:

and 4e, realizing water resource recycling through technical matching.

8. The method of claim 1, wherein in step 6, a new cycle of high-volume nitrogen foam water pressing cone is developed for the first-line well according to production needs, and the cycle is repeated as long as the effect is good.

9. The new method for improving the development effect of the ultra heavy oil side water reservoir according to claim 8, wherein the step 6 comprises:

3f, repeating the steps repeatedly as long as the effect is good;