Shale oil reservoir treatment well selection method

Abstract

The application discloses a shale oil reservoir measure well selection method, which comprises the following steps: step 1: according to the logging parameters, the geological factor is obtained; according to the liquid injection amount of each well, the engineering factor is obtained; wherein the porosity after logging interpretation, the permeability after logging interpretation, the saturation after logging interpretation, the interpreted thickness of the horizontal section, the length of the horizontal section, the sum of the thicknesses of the I and II types drilled by the horizontal section and the single layer thickness after logging interpretation; the liquid injection amount of each well refers to the liquid injection amount of the fracturing operation of each well; step 2: according to the geological factor and the engineering factor, the geological engineering factor is calculated; according to the production condition of the well, the production cycle is averagely divided into blocks, and the block decline rate in each cycle is calculated; according to the block decline rate in different cycles, the block annual decline rate is obtained; step 3: according to the initial production of the well, the block annual decline rate and the production time, the current theoretical production is calculated; step 4: according to the current theoretical production, the initial production, the block annual decline rate and the current actual production, the production factor is calculated; step 5: according to the production factor and the geological engineering factor, the two-dimensional image representation is carried out; and combined with the yield change rule before and after the measure, the two-dimensional image representation is distinguished to determine whether the measure is taken.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil exploration and development, in particular to a shale oil reservoir treatment well selection method. BACKGROUND

[0002] With the increasing exploration of conventional oil resources, the exploration difficulty is increasing, the quality of newly added reserves is poor, the recovery rate is low, and the developed oilfields have entered the production decline period one after another, making it difficult to maintain and increase production. Therefore, the petroleum industry is striving to find major replacement resources, from conventional oil and gas to unconventional oil and gas. Unconventional oil and gas mainly includes shale oil (gas) and tight oil (gas). As one of the unconventional oil and gas resources, tight oil is widely distributed and has great resource potential, with a global technically recoverable reserve of about 639.3×10 8 t, becoming a new hotspot in the global exploration and development of unconventional oil and gas, known as the "black gold" in the oil industry.

[0003] Due to the late start of unconventional oil and gas exploration, but the resources are abundant and the distribution range is wide. In recent years, exploration discoveries and breakthroughs have been made in many basins, and a number of large-scale production areas have been initially built. By 2022, the proven unconventional oil and gas geological reserves have reached 7.37×10 8 t, and the production capacity of more than 400×10 4 t / a has been built.

[0004] Due to the poor physical properties of unconventional reservoirs, it is difficult to exploit them by natural energy, and it is necessary to supplement energy through volume fracturing to realize exploitation. Therefore, the production well type commonly used for developing such reservoirs is horizontal well. However, there is no distinction in the selection of well treatment, and for waxy reservoirs, wax will be deposited on the inner wall of the casing and the inner wall of the tubing after the horizontal well has been produced for a period of time. The so-called wax deposition phenomenon refers to the fact that for crude oil containing a certain amount of paraffin, during the production process, as the temperature and pressure decrease and gas is precipitated, the dissolved paraffin is precipitated, aggregated and deposited on the surface of the solid phase, such as the pipe wall. For reservoirs with high formation water salinity, during the production process, water scale will be formed on the pipe wall as the reservoir is continuously exploited, thereby affecting normal production; for unconventional reservoirs, due to the fine reservoir lithology, sand production often occurs during production, which also causes abnormal production conditions. Whether it is wax, scale or sand, most of them will cause the load to increase, reducing the service life of the oil rod and the oil pipe; at the same time, it will also make the oil pipe section smaller to cause blockage, increase the oil rod diameter, increase the oil flow resistance, easily lead to oil well blockage, pump sticking and pump leakage, affect the normal production of oil wells, reduce the production of pumping wells, and even cause the oil well to stop production, affecting the treatment effect of the well.

[0005] Therefore, based on the above problems, how to determine whether a well should be treated or not is a problem we need to face and solve. SUMMARY

[0006] In view of the problem in the prior art that no distinction is made in the selection of measures for a well, resulting in unsatisfactory measure effects and waste of production resources, the present application provides a shale oil reservoir measure well selection method, which can quickly determine the quality of the geological conditions of an oil well and the quality of the engineering factors added by a fracturing project, and effectively improves the accuracy of measure well selection and determination.

[0007] The present application is achieved by the following technical solutions:

[0008] A shale oil reservoir measure well selection method, the selection method comprising the following steps:

[0009] Step 1: According to the logging parameters, the geological factors are calculated; according to the liquid addition amount of each well, the engineering factors are calculated; wherein the porosity after logging interpretation, the permeability after logging interpretation, the saturation after logging interpretation, the interpreted thickness of the horizontal section, the length of the horizontal section, the sum of the thicknesses of types I and II encountered by the horizontal section, and the single-layer thickness after logging interpretation; the liquid addition amount of each well refers to the liquid addition amount of the fracturing operation of each well;

[0010] Step 2: According to the geological factors and the engineering factors, the geological engineering factors are calculated; according to the production conditions of the well, the production cycle is averaged to divide the blocks, and the block decline rate in each cycle is calculated; according to the block decline rate in different cycles, the block annual decline rate is obtained;

[0011] Step 3: According to the initial production of the well, the block annual decline rate and the production time, the current theoretical production is calculated;

[0012] Step 4: According to the current theoretical production, the initial production, the block annual decline rate and the current actual production, the production factor is calculated;

[0013] Step 5: According to the production factor and the geological engineering factor, a two-dimensional image is represented; and combining the production change rule before and after the measures, whether to take measures is determined by distinguishing the two-dimensional image representation.

[0014] Further, the geological factors are calculated according to the following formula:

[0015] .

[0016] Further, the engineering factors are calculated according to the following formula:

[0017] .

[0018] Further, the address engineering factors are calculated according to the following formula:

[0019] .

[0020] Further, the block decline rate is calculated separately for the time period in which the decline rate is greater than 50% during the calculation process.

[0021] Further, according to the block annual decline rate, and in the case of using years as the unit of production time, the formula of the current theoretical production is as follows:

[0022] ;

[0023] According to the block annual decline rate, and in the case of using months as the unit of production time, the formula of the current theoretical production is as follows:

[0024] .

[0025] Further, in the case of obtaining the block annual decline rate and using years as the unit of production time, the formula is as follows:

[0026] ;

[0027] In the case of obtaining the block annual decline rate and using months as the unit of production time, the formula is as follows:

[0028] .

[0029] Further, according to the two-dimensional image representation of the geological engineering factor and the production factor, the geological engineering conditions are divided: the well with the production factor greater than or equal to 2.0±0.5 is selected for measures.

[0030] Compared with the prior art, the present application has the following beneficial technical effects:

[0031] In order to more clearly judge whether the production well needs to be taken measures, the present application provides a shale oil reservoir measure well selection method, through the calculation of the geological factor and the engineering factor by the logging parameter, the good and bad of the geological conditions of the oil well and the pros and cons of the additional engineering factors of the fracturing engineering can be quickly judged, at the same time, according to the geological engineering factor and the production cycle, the increase of the oil reservoir decline rate, the production time and the theoretical production are judged and considered, the accuracy of the measure well optimization judgment is effectively improved, a strong and effective guarantee is provided for the stable production and production of unconventional oil reservoirs, and technical support is provided for solving the actual problems of similar oil reservoir development and production.

[0032] Further, the application provides a shale oil reservoir treatment well selection method, which combines multiple reservoir parameters such as porosity, permeability, saturation and thickness of geology itself; considers the fracturing fluid volume of the formation added in fracturing treatment and other engineering parameters to obtain a geological engineering factor; considers the unconventional reservoir decline factor to obtain a current theoretical yield, a difference between the theoretical yield and an actual yield, a production factor, and an identification chart of the geological engineering factor and the production factor. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0034] Figure 1 The unconventional reservoir treatment well selection chart of the shale oil reservoir treatment well selection method provided by the embodiments of the present application. DETAILED DESCRIPTION

[0035] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0036] The embodiments of the present application will be described in detail below with reference to the drawings.

[0037] When the unconventional reservoir resource amount of an oilfield is large, horizontal wells are mainly used for exploitation. However, due to the high wax content, high scale content and high sand content of the regional crude oil, the normal production capacity will be affected in the production process. The embodiments of the present application provide a preferred shale oil reservoir treatment well selection method, which is suitable for judging whether the unconventional reservoir production well needs to be treated after a period of production.

[0038] The selection method includes the following steps:

[0039] Step one, obtaining a geological factor.

[0040] According to the porosity after well logging interpretation, the permeability after well logging interpretation, the saturation after well logging interpretation, the single layer thickness after well logging interpretation, the interpreted thickness of the horizontal section or the length of the horizontal section or the sum of the thicknesses of the I and II types drilled by the horizontal section, the geological factor per meter is obtained.

[0041] The specific formula is as follows:

[0042] ;

[0043] After a horizontal well is completed, the geological condition is fixed, and the geological condition is positively correlated with porosity, permeability, and saturation, that is, the higher the porosity, the better the geological condition, the higher the permeability, the better the geological condition, and the higher the saturation, the better the geological condition. The porosity after well logging interpretation, the permeability after well logging interpretation, the saturation after well logging interpretation, the single layer thickness after well logging interpretation, the length of the horizontal section or the interpreted thickness of the horizontal section or the sum of the thicknesses of the first and second types drilled by the horizontal section can clearly reflect the geological factors of the well.

[0044] Step two, obtain the engineering factor.

[0045] For unconventional reservoirs, horizontal wells need to be fractured after completion; the quality of fracturing is directly related to the amount of sand and liquid added. Sand addition mainly plays a supporting role in fracturing the formation.

[0046] The amount of liquid added is the main engineering parameter. Generally, the larger the amount of liquid added in fracturing operations, the better the fracturing effect, the higher the formation energy, and the better the development effect. Therefore, the engineering factor per meter is obtained according to the amount of liquid added in the fracturing operation of each well.

[0047] The specific formula is as follows:

[0048] ;

[0049] Step three, obtain the geological engineering factor, referred to as GEF.

[0050] After a well is completed and fractured, the geological engineering factor is fixed, and the geological engineering factor is positively correlated with the geological factor and the engineering factor.

[0051] The specific formula is as follows:

[0052] ;

[0053] Step four, obtain the decline rate of the block.

[0054] According to the production situation of old wells, the production cycle is divided into blocks:

[0055] The first way: when the production cycle is longer, greater than or equal to two years, according to the production situation of old wells, the annual decline rate is obtained, and the decline rates of all wells are averaged to obtain the block annual decline rate.

[0056] For the case where the first year decline rate is greater than or equal to 50%, the decline rate of the new well in the first year is separately obtained, or the decline rates of the second year, the third year, …, the nth year are obtained. After averaging the blocks, the decline rate of the averaged block is calculated, and the production law of the block is clearly expressed in turn.

[0057] The second method: When the production cycle is long, greater than or equal to two months, the monthly decline rate is calculated based on the production of old wells, and the decline rates of all wells are averaged to obtain the monthly decline rate of the block.

[0058] If the decline rate in the first month is greater than or equal to 50%, the decline rate of the new well in the first month of production is calculated separately, or the decline rate in the second month, the third month, ... the nth month, etc. is calculated.

[0059] In the actual calculation process, it is necessary to average the blocks and then calculate the decrease rate of the average blocks to clearly express the production law of the blocks.

[0060] Step 5: Calculate the current theoretical production of a single well.

[0061] The current theoretical yield is related to the initial yield, production time and annual decline rate of the block.

[0062] When the annual decline rate of blocks is obtained and the production time is measured in years, the current theoretical output formula is as follows:

[0063]

[0064] When the annual decline rate of blocks is calculated and the production time is in months, the current theoretical output formula is as follows:

[0065] .

[0066] Step 6. Calculate the production factor, which can be abbreviated as △P.

[0067] The current theoretical output is related to the initial output, production time and the annual decline rate of the block. When the annual decline rate of the block is obtained and the production time is in years, the current theoretical output formula is as follows:

[0068]

[0069] To find the annual block decline rate and the production time is in months, the formula is as follows:

[0070] .

[0071] Step 7: Create production factor and geological engineering factor charts.

[0072] The horizontal axis is the geological engineering factor, and the vertical axis is the production factor. An intersection diagram is drawn up and a production factor and geological engineering factor chart is established.

[0073] Step eight, the actual measures data, including the daily oil increment data before and after the measures, the initial production of measures, the production after measures, the production time, the length of the horizontal section, the interpreted length of the horizontal section, the sum of the thickness of the I and II classes drilled by the horizontal section, the porosity after well logging interpretation, the permeability after well logging interpretation, the saturation after well logging interpretation, the thickness parameter, are calculated to obtain the geological engineering factor and the production factor, and a production factor and geological engineering factor chart is established.

[0074] As shown in Figure 1 According to the production change rule before and after the measures, the chart is divided into four types, I, II, III and IV.

[0075] I represents good geological engineering conditions, large production gap, and large production increase space after measures.

[0076] II represents general geological engineering conditions, large production gap, and possible large production increase space after measures.

[0077] III represents good geological engineering conditions, small production gap, and no need for further measures.

[0078] IV represents general geological engineering conditions, small production gap, and no need for further measures.

[0079] The technical solution provided by the present application establishes a geological engineering factor by considering the geological conditions of the oil well itself and the engineering factors added by fracturing engineering.

[0080] At the same time, the technical solution of the present application considers factors such as reservoir decline rate, production time and theoretical production, establishes a production factor, and establishes the gap of theoretical production through the production factor, that is, the reference value of the measure theoretical increment, so that the selection of whether the unconventional reservoir production well needs to be measured is more targeted, while ensuring effectiveness and accuracy.

[0081] Therefore, the technical solution has important practical significance for ensuring the reasonable and normal production of unconventional reservoirs, and provides a reference for the production and exploitation of unconventional reservoirs.

[0082] The foregoing merely illustrates the principles of the application and application of its leading features. This application is not limited to the exact details shown above and described herein, and obvious modifications will occur to those skilled in the art upon reading the foregoing description. Therefore, the scope of the application is not to be determined by such exemplary teachings but only by the claims and equivalents thereof. Any reference to claim elements in the singular, for example, using the articles "a," "an," "the" or "said," is not construed as being limited to a single element but intended to include the plural, unless specifically qualified by terms to the contrary.

[0083] In addition, it should be understood that although the description herein is based on embodiments, not every embodiment contains only one independent technical solution, and the description herein is only for the sake of clarity, and those skilled in the art should consider the description as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand. The above is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made on the basis of the technical idea of the present application to the technical solution falls within the protection scope of the claims of the present application.

Claims

1. A method for selecting a shale oil reservoir treatment well, characterized in that: The selection method includes the following steps: Step 1: Calculate geological factors based on well logging parameters; calculate engineering factors based on the fluid injection volume for each well; the factors include porosity after well logging interpretation, permeability after well logging interpretation, saturation after well logging interpretation, interpreted thickness of the horizontal section, length of the horizontal section, the sum of the thickness of Class I and Class II encountered in the horizontal section, and the thickness of the single layer after well logging interpretation; the fluid injection volume for each well refers to the fluid injection volume for the fracturing operation of each well; Step 2: Calculate the geological and engineering factors based on the geological factors and engineering factors; divide the production cycle into blocks based on the production situation of the well, and calculate the block decline rate within each cycle; obtain the block annual decline rate based on the block decline rate in different cycles; Step 3: Calculate the current theoretical production based on the well's initial production, the block's annual decline rate, and production time; Step 4: Calculate the production factor based on the current theoretical output, initial output, annual decline rate of the block and current actual output; Step 5: Make a two-dimensional image representation based on production factors and geological engineering factors; and combine the production change rules before and after the measures to distinguish the two-dimensional image representation and determine whether to take measures.

2. The method for selecting a shale oil reservoir treatment well according to claim 1, characterized in that: The geological factor is calculated according to the following formula: 。 3. The method for selecting a shale oil reservoir treatment well according to claim 1, characterized in that: The engineering factor is calculated according to the following formula: 。 4. The method for selecting a shale oil reservoir treatment well according to claim 1, wherein: The address engineering factor is calculated according to the following formula: 。 5. The method for selecting a shale oil reservoir treatment well according to claim 1, characterized in that: During the calculation of the block decrease rate, the decrease rate is calculated separately for the time period when the decrease rate is greater than 50%.

6. The method for selecting a shale oil reservoir treatment well according to claim 1, characterized in that: Based on the annual block decline rate and the production time in years, the current theoretical output formula is as follows: ； Based on the annual block decline rate and the production time in months, the current theoretical output formula is as follows: 。 7. The method for selecting a shale oil reservoir treatment well according to claim 1, characterized in that: To find the annual block decline rate and the production time is in years, the formula is as follows: ； To find the annual block decline rate and the production time is in months, the formula is as follows: 。

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