A method for calculating shale oil reservoir reserves and oil phase volume of each occurrence state

Abstract

The application relates to the technical field of shale oil reservoir exploration and development, and discloses a shale oil reservoir reserve and a calculation method of the volume of each occurrence state oil phase, which measures and calculates basic physical parameters of shale through experiments, establishes a theoretical calculation model of total oil content and the volume of each occurrence state oil phase of the shale oil reservoir, and can accurately calculate the volume of inorganic free state oil phase in inorganic pores, the volume of organic free state oil phase in organic pores, the volume of dissolved state oil phase in organic matter and the total oil content in the shale oil reservoir based on the model. The application can accurately calculate the total oil content and the volume of each occurrence state oil phase of the shale oil reservoir, realizes fine evaluation of the shale oil reservoir reserve, and provides key basic data for shale oil reservoir reserve evaluation and efficient development.

Description

Technical Field

[0001] This invention belongs to the field of shale oil reservoir exploration and development technology, specifically a method for calculating the reserves of shale oil reservoirs and the volume of each oil phase in its occurrence state. Background Technology

[0002] Shale oil refers to petroleum stored in organic-rich black shale formations, and is an unconventional petroleum resource. Compared with conventional petroleum resources, shale oil reservoirs are characterized by diverse mineral composition, low porosity and permeability, complex pore-throat structure, multiple pore types, strong heterogeneity, and diverse fluid occurrence forms. Conventional reserve evaluation methods cannot accurately characterize the oil content of shale oil reservoirs. The porosity of shale reservoirs is mainly divided into two categories: one is the pores distributed between or within inorganic mineral particles, called inorganic pores; the other is the pores developed within organic matter, mainly kerogen, called organic pores. Oil in shale oil reservoirs exists primarily in two states: free and dissolved. The free oil phase is further stored in inorganic and organic pores, referred to as inorganic free oil phase and organic free oil phase, respectively. The oil phase existing in the dissolved state within organic polymer condensates is called dissolved oil phase. Therefore, oil phases in shale reservoirs exist in three ways: inorganic free oil phase in inorganic pores, organic free oil phase in organic pores, and dissolved oil phase within organic matter. Accurate measurement of the total oil content and the volume of the three types of oil phases in shale oil reservoirs will affect the evaluation of shale oil resources and production capacity analysis. Accurate partitioning of the volumes of the three types of oil phases will provide key basic data for the efficient development of shale oil reservoirs.

[0003] Currently, the main experimental methods for evaluating the oil content of shale oil reservoirs are pore volume analysis, oil phase saturation experiments, and the chloroform-asphalt "A" method. However, these methods can only measure the total oil content and cannot simultaneously measure the oil content in inorganic pores, organic pores, and dissolved oil. Pore volume analysis methods mainly include high-pressure mercury intrusion porosimetry, gas analysis, and nuclear magnetic resonance (NMR) measurements. However, these methods primarily measure the pore size distribution of shale. By providing pore size values ​​that distinguish between inorganic and organic pores, the volumes of organic and inorganic pores are divided. However, due to the heterogeneity of shale pore distribution, there are small pores in inorganic pores and large pores in organic pores. Therefore, the division results cannot accurately characterize the oil content in inorganic and organic pores, and cannot measure the dissolved oil content. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, this invention provides a method for calculating the reserves of shale oil reservoirs and the volume of each oil phase in its occurrence state, which effectively solves the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for calculating the reserves of shale oil reservoirs and the volume of each oil phase in its occurrence state, comprising the following steps;

[0006] Step 1: Determine the total porosity φ of shale, the porosity φ1 of inorganic pores in shale, and the porosity φ2 of organic pores in shale;

[0007] Step 2: Determine the total organic carbon (TOC) content and apparent density (ρ) of the shale. f ;

[0008] Step 3: Determine the density ρ of the inorganic framework of shale. s1 and organic matter skeleton density ρ s2 ;

[0009] Step 4: Calculate the apparent volume V of inorganic matter in shale. f1 and apparent volume of organic matter V f2 ;

[0010] Step 5: Calculate the apparent density ρ of shale inorganic matter. f1 and apparent density of organic matter ρ f2 ;

[0011] Step Six: Calculate the inorganic porosity φ of shale. f1 and organic matter porosity φ f2 ;

[0012] Step 7: Calculate the total oil content and the volume of each oil phase in the shale oil reservoir.

[0013] Preferably, step one further includes: experimentally determining the total porosity φ (decimal) of the shale oil reservoir core under study.

[0014] Preferably, step two further includes: experimentally determining the total organic carbon content (TOC, wt%, mass percentage) and apparent density (ρ) of the shale. f (g / cm^3);

[0015] The total organic carbon (TOC) content of shale is defined as the mass of organic matter in shale (m). f2 (g) and shale mass m f The ratio of (g), that is

[0016] Shale apparent density ρ f Shale mass m f With shale apparent volume V f The ratio, that is

[0017] To simplify the calculation notation, let a = ρ f (1-TOC), b=ρ fTOC, where a and b represent the mass of inorganic matter and organic matter in 1 cm³ of shale, respectively, in grams.

[0018] Preferably, step three further includes: experimentally determining the composition of inorganic minerals in the shale, assuming there are n kinds of inorganic minerals, and determining the mass percentage c of each inorganic mineral. i (i = 1, 2, ..., n) and the skeletal density ρ of each inorganic mineral i (g / cm^3), the skeletal density of inorganic minerals is a standard constant value. The inorganic mineral mass percentage is used as a weighting factor, and the density ρ of the shale inorganic skeletal density is obtained by density-weighted averaging. s1 (g / cm^3), its calculation formula is:

[0019]

[0020] Based on the apparent density ρ of shale f Calculate the shale skeleton density ρ based on the total porosity φ of the shale. s (g / cm^3), its calculation formula is:

[0021]

[0022] Based on the shale skeleton density ρ s And the inorganic skeleton density ρ of shale s1 The organic matter skeleton density ρ of shale was calculated. s2 (g / cm^3), its calculation formula is:

[0023]

[0024] Preferably, step four further includes: for the apparent volume V f For shale with a density of 1 cm³, the apparent volume of inorganic matter V of the shale is... f1 (cm^3) can be calculated using the following formula:

[0025]

[0026] apparent volume V of shale organic matter f2 (cm^3) can be calculated using the following formula:

[0027]

[0028] Preferably, step five further includes: the apparent density ρ of shale inorganic matter. f1 (g / cm^3) is defined as the mass of inorganic matter in shale m f 1 and the apparent volume V of inorganic matter f1 The ratio, that is apparent density of organic matter in shale ρ f2(g / cm^3) is defined as the mass of organic matter in shale m f2 With the apparent volume V of organic matter f2 The ratio, that is

[0029] apparent density of inorganic matter in shale, ρ f1 The calculation formula is:

[0030]

[0031] apparent density of organic matter in shale ρ f2 The calculation formula is:

[0032]

[0033] Preferably, step five further includes: shale inorganic porosity φ f1 Defined as the inorganic pore volume V of shale p1 (cm^3) and apparent volume of inorganic matter V f1 The ratio of (cm^3), that is The calculation formula is as follows:

[0034]

[0035] Shale organic matter porosity φ f2 Defined as organic pore volume V p2 (cm^3) and apparent volume of organic matter V f2 The ratio of (cm^3), that is The calculation formula is as follows:

[0036]

[0037] Preferably, step seven further includes: for an apparent volume of V f The volume V of inorganic free oil phase in inorganic pores of a shale reservoir with a density of (cm^3) o1 (cm^3) can be expressed by the following formula:

[0038]

[0039] Volume V of organic free oil phase in organic pores o2 (cm^3) can be expressed by the following formula:

[0040]

[0041] The solubility R of organic matter per unit volume in the oil phase was measured experimentally. s (cm^3 / cm^3), the volume V of the dissolved oil phase inside the organic matter. o3 (cm^3) can be expressed by the following formula:

[0042]

[0043] Total oil content V o Expressed as follows:

[0044]

[0045] Alternatively, it can be expressed as the total porosity φ of shale:

[0046]

[0047] Preferably, the determination of the total porosity φ of shale cores further includes:

[0048] Because the wettability of organic pores is oil-phase wettability, and the pore size of organic pores is relatively small, the aqueous phase has difficulty entering the organic pores due to the influence of wettability and capillary forces. Therefore, by conducting experiments on shale cores after vacuuming and saturating them with water, the porosity φ1 (decimal) of the inorganic pores in shale can be measured. φ1 is defined as the inorganic pore volume V. p1 (cm^3) and apparent volume V of shale f The ratio of (cm^3), that is

[0049] The methods for measuring the total porosity φ and inorganic porosity φ1 of shale are well known to those skilled in the art;

[0050] The porosity φ2 (decimal) of organic pores in shale is defined as the organic pore volume V. p2 (cm^3) and apparent volume V of shale f The ratio of (cm^3), that is

[0051] Since the total porosity φ of shale is equal to the sum of the porosity φ1 of inorganic pores and the porosity φ2 of organic pores in shale, i.e. φ=φ1+φ2, the porosity φ2 of organic pores in shale can be obtained from the total porosity φ and the porosity φ1 of inorganic pores. The calculation formula is: φ2=φ-φ1.

[0052] Compared with the prior art, the beneficial effects of the present invention are:

[0053] 1. This paper proposes a method for calculating the reserves and volumes of various oil phases in shale oil reservoirs. This method can measure the volume of inorganic free oil phase, organic free oil phase in organic pores, dissolved oil phase inside organic matter, and total oil content in shale oil reservoirs, thereby enabling detailed subdivision and accurate measurement of oil content in shale oil reservoirs.

[0054] 2. This paper proposes a method for calculating the reserves and volumes of oil phases in various occurrence states of shale oil reservoirs. This method can simultaneously calculate unconventional physical property parameters such as the mass, apparent density, framework density, porosity, and apparent volume of inorganic and organic matter in shale, providing richer basic data for the evaluation of shale reservoir properties.

[0055] 3. This paper proposes a method for calculating the reserves of shale oil reservoirs and the volume of oil phases in various occurrence states. It is highly operable, has a clear principle, and has high measurement accuracy. Attached Figure Description

[0056] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0057] In the attached diagram:

[0058] Figure 1 A flowchart illustrating a method for calculating shale oil reservoir reserves and the volume of oil phases in various occurrence states, provided by this invention. Detailed Implementation

[0059] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0060] A method for calculating the reserves of shale oil reservoirs and the volume of oil phases in various occurrence states, comprising the following steps;

[0061] Step 1: Determine the total porosity φ of shale, the porosity φ1 of inorganic pores in shale, and the porosity φ2 of organic pores in shale.

[0062] For the shale oil reservoir cores studied, the total porosity φ (decimal) of the shale cores was experimentally determined. Since the wettability of organic pores is oil-phase wettability, and the pore size of organic pores is small, the aqueous phase has difficulty entering the organic pores due to wettability and capillary forces. Therefore, by conducting an experiment on the shale cores after vacuuming and saturating them with water, the porosity φ1 (decimal) of the inorganic pores in the shale can be measured. φ1 is defined as the inorganic pore volume V. p1 (cm^3) and apparent volume V of shale f The ratio of (cm^3), that is The methods for measuring the total porosity φ and inorganic porosity φ1 of shale are well known to those skilled in the art and will not be elaborated here.

[0063] The porosity φ2 (decimal) of organic pores in shale is defined as the organic pore volume V.p2 (cm^3) and apparent volume V of shale f The ratio of (cm^3), that is Since the total porosity φ of shale is equal to the sum of the porosity φ1 of inorganic pores and the porosity φ2 of organic pores in shale, i.e. φ=φ1+φ2, the porosity φ2 of organic pores in shale can be obtained from the total porosity φ and the porosity φ1 of inorganic pores. The calculation formula is: φ2=φ-φ1.

[0064] Step 2: Determine the total organic carbon (TOC) content and apparent density (ρ) of the shale. f .

[0065] The total organic carbon content (TOC, wt%, mass percentage) and apparent density (ρ) of shale were determined experimentally. f (g / cm^3). The total organic carbon (TOC) content of shale is defined as the mass of organic matter in shale (m). f2 (g) and shale mass m f The ratio of (g), that is Shale apparent density ρ f Shale mass m f With shale apparent volume V f The ratio, that is

[0066] To simplify the calculation notation, let a = ρ f (1-TOC), b=ρ f TOC, where a and b represent the mass of inorganic matter and organic matter in 1 cm³ of shale, respectively, in grams.

[0067] Step 3: Determine the density ρ of the inorganic framework of shale. s1 and organic matter skeleton density ρ s2 .

[0068] The composition of inorganic minerals in shale was experimentally determined. Assuming there are n types of inorganic minerals, the mass percentage c of each inorganic mineral was calculated. i (i = 1, 2, ..., n) and the skeletal density ρ of each inorganic mineral i (g / cm^3), the skeletal density of inorganic minerals is a standard constant value. The inorganic mineral mass percentage is used as a weighting factor, and the density ρ of the shale inorganic skeletal density is obtained by density-weighted averaging. s1 (g / cm^3), its calculation formula is:

[0069]

[0070] Based on the apparent density ρ of shale f Calculate the shale skeleton density ρ based on the total porosity φ of the shale. s (g / cm^3), its calculation formula is:

[0071]

[0072] Based on the shale skeleton density ρ s And the inorganic skeleton density ρ of shale s1 The organic matter skeleton density ρ of shale was calculated. s2 (g / cm^3), its calculation formula is:

[0073]

[0074] Step 4: Calculate the apparent volume V of inorganic matter in shale. f1 and apparent volume of organic matter V f2 .

[0075] For apparent volume V f For shale with a density of 1 cm³, the apparent volume of inorganic matter V of the shale is... f1 (cm^3) can be calculated using the following formula:

[0076]

[0077] apparent volume V of shale organic matter f2 (cm^3) can be calculated using the following formula:

[0078]

[0079] Step 5: Calculate the apparent density ρ of shale inorganic matter. f1 and apparent density of organic matter ρ f2 .

[0080] apparent density of inorganic matter in shale, ρ f1 (g / cm^3) is defined as the mass of inorganic matter in shale m f1 With the apparent volume V of inorganic matter f1 The ratio, that is apparent density of organic matter in shale ρ f2 (g / cm^3) is defined as the mass of organic matter in shale m f2 With the apparent volume V of organic matter f2 The ratio, that is

[0081] apparent density of inorganic matter in shale, ρ f1 The calculation formula is:

[0082]

[0083] apparent density of organic matter in shale ρ f2 The calculation formula is:

[0084]

[0085] Step Six: Calculate the inorganic porosity φ of shale. f1 and organic matter porosity φ f2 .

[0086] Shale inorganic porosity φ f1 Defined as the inorganic pore volume V of shale p1 (cm^3) and apparent volume of inorganic matter V f1 The ratio of (cm^3), that is The calculation formula is as follows:

[0087]

[0088] Shale organic matter porosity φ f2 Defined as organic pore volume V p2 (cm3^) and apparent volume of organic matter V f2 The ratio of (cm^3), that is The calculation formula is as follows:

[0089]

[0090] Step 7: Calculate the total oil content of the shale oil reservoir and the volume of each oil phase in its occurrence state.

[0091] For an apparent volume of V f The volume V of inorganic free oil phase in inorganic pores of a shale reservoir with a density of (cm^3) o1 (cm^3) can be expressed by the following formula:

[0092]

[0093] Volume V of organic free oil phase in organic pores o2 (cm^3) can be expressed by the following formula:

[0094]

[0095] The solubility R of organic matter per unit volume in the oil phase was measured experimentally. s (cm^3 / cm^3), the volume V of the dissolved oil phase inside the organic matter. o3 (cm^3) can be expressed by the following formula:

[0096]

[0097] Total oil content V o Expressed as follows:

[0098]

[0099] Alternatively, it can be expressed as the total porosity φ of shale:

[0100]

[0101] Example

[0102] First, the physical properties of the shale were determined. For a specific shale sample, the total organic carbon (TOC) content was measured to be 4.87 wt%, the total porosity (φ) was 7.12%, and the solubility R of organic matter per unit volume in the oil phase was [not specified]. s =0.12cm^3 / cm^3, inorganic porosity φ1 = 5.35%, shale apparent density ρ f = 2.405 g / cm^3.

[0103] The composition and mass percentage of various inorganic minerals in shale were experimentally measured, and the results, along with the skeletal density of each inorganic mineral, are listed below:

[0104]

[0105]

[0106] Using the mass percentage of inorganic minerals as weighting coefficients, the density ρ of the shale inorganic framework is obtained through density-weighted averaging. s1 = 2.751 g / cm^3.

[0107] Then, the physical properties of the shale are calculated using the formulas in the implementation method.

[0108] The organic porosity of shale is φ2 = 1.8%.

[0109] The inorganic and organic matter masses in 1 cm³ of shale are a = 2.288 g and b = 0.117 g, respectively.

[0110] Shale skeleton density ρ s =2.589g / cm^3.

[0111] Organic matter skeleton density ρ s2 = 1.206 g / cm^3.

[0112] apparent volume V of inorganic matter f1 =0.89cm^3.

[0113] apparent volume V of organic matter f2 =0.11cm^3.

[0114] apparent density ρ of inorganic matter f1 =2.585g / cm^3.

[0115] apparent density of organic matter ρ f2 = 1.020 g / cm^3.

[0116] Inorganic porosity φf1 =6.04%.

[0117] Organic porosity φ f2 =15.41%.

[0118] Finally, the total volumetric oil content of each oil phase in the shale oil reservoir was calculated.

[0119] For an apparent volume of V f =1 cm^3 shale reservoir, inorganic free oil phase volume V o1 = 0.054cm^3.

[0120] Organic free oil phase volume V o2 =0.018cm^3.

[0121] Dissolved oil phase volume V o3 = 0.014cm^3.

[0122] Total oil content V o =0.085cm^3.

[0123] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0124] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for calculating the reserves of shale oil reservoirs and the volume of oil phases in various occurrence states, characterized in that: The steps include; Step 1: Determine the total porosity of shale. Porosity of inorganic pores in shale Porosity of organic pores in shale ; Step 2: Determine the total organic carbon (TOC) content and apparent density of shale. ; Step two also includes: experimentally determining the total organic carbon content (TOC), wt%, mass percentage, and apparent density of the shale. g / cm^3; The total organic carbon (TOC) content of shale is defined as the mass of organic matter in shale. g, and shale quality The ratio of g to g, i.e. ; Shale apparent density For shale quality With shale apparent volume The ratio, that is ; To simplify the calculation notation, let , a and b represent the mass of inorganic matter and organic matter in 1 cm³ of shale, respectively, in grams. Step 3: Determine the density of the inorganic framework of shale. and organic matter skeleton density ; Step 4: Calculate the apparent volume of inorganic matter in shale. and apparent volume of organic matter ; Step 5: Calculate the apparent density of inorganic matter in shale. and apparent density of organic matter ; Step Six: Calculate the porosity of inorganic matter in shale. and organic matter porosity ; Step 7: Calculate the total oil content and volume of each oil phase in the shale oil reservoir; Step seven also includes: for an apparent volume of The volume of inorganic free oil phase in the inorganic pores of shale reservoirs, cm^3. cm^3 is expressed by the following formula: ； Volume of organic free oil phase in organic pores cm^3 is expressed by the following formula: ； The solubility of organic matter per unit volume in the oil phase was measured experimentally. , cm^3 / cm^3, the volume of dissolved oil phase inside the organic matter cm^3 is expressed by the following formula: ； Total oil content Expressed as follows: ， Or use the total porosity of shale Represented as: 。 2. The method for calculating the reserves and oil phase volume of shale oil reservoirs in each occurrence state according to claim 1, characterized in that, Step one also includes: experimentally determining the total porosity of the shale oil reservoir core under study. .

3. The method for calculating the reserves and oil phase volume of a shale oil reservoir according to claim 2, characterized in that, Step three also includes: experimentally determining the composition of inorganic minerals in the shale, assuming there are n kinds of inorganic minerals, and determining the mass percentage of each inorganic mineral. , i = 1, 2, …, n, and the skeletal density of each inorganic mineral. The inorganic mineral framework density (g / cm^3) is a standard constant value. The inorganic mineral mass percentage is used as a weighting factor, and the density of the shale inorganic framework is obtained through density-weighted averaging. , g / cm^3, its calculation formula is: ； Based on the apparent density of shale and total porosity of shale Calculate the density of the shale skeleton. , g / cm^3, its calculation formula is: ； Based on shale skeleton density and the density of shale inorganic framework The organic matter skeleton density of shale was calculated. , g / cm^3, its calculation formula is: 。 4. The method for calculating the reserves and oil phase volume of a shale oil reservoir according to claim 3, characterized in that, Step four also includes: for apparent volume Shale with a density of 1 cm³, the apparent volume of inorganic matter in shale. The value of cm^3 can be calculated using the following formula: ； apparent volume of shale organic matter The value of cm^3 can be calculated using the following formula: 。 5. The method for calculating the reserves and oil phase volume of a shale oil reservoir according to claim 4, characterized in that, Step five also includes: apparent density of shale inorganic matter. g / cm^3 is defined as the mass of inorganic matter in shale. With the apparent volume of inorganic matter The ratio, that is ; apparent density of shale organic matter g / cm^3 is defined as the mass of organic matter in shale. With the apparent volume of organic matter The ratio, that is ; apparent density of inorganic matter in shale The calculation formula is: ； apparent density of organic matter in shale The calculation formula is: 。 6. The method for calculating the reserves and oil phase volume of a shale oil reservoir according to claim 5, characterized in that, Step six also includes: shale inorganic porosity Defined as the inorganic pore volume of shale. cm^3, and the apparent volume of inorganic matter The ratio of cm^3, i.e. The calculation formula is as follows: ； Shale organic matter porosity Defined as organic pore volume cm^3, and the apparent volume of organic matter The ratio of cm^3, i.e. The calculation formula is as follows: 。 7. The method for calculating the reserves and oil phase volume of a shale oil reservoir according to claim 6, characterized in that, Determining the total porosity of shale cores Also includes: Because the wettability of organic pores is oil-phase wettability, and the pore size of organic pores is relatively small, the aqueous phase has difficulty entering the organic pores due to the influence of wettability and capillary forces. Therefore, by conducting experiments on shale cores after vacuum extraction and saturation with water, the porosity of inorganic pores in shale can be measured. , Defined as inorganic pore volume cm^3, and the apparent volume of shale The ratio of cm^3, i.e. ; Measuring the total porosity of shale and inorganic porosity ; Define the porosity of organic pores in shale. Organic pore volume cm^3, and the apparent volume of shale The ratio of cm^3, i.e. ; Due to the total porosity of shale Porosity equal to inorganic pores Porosity of organic pores in shale The sum of Based on the total porosity of shale Porosity of inorganic pores The porosity of organic pores in shale can be obtained. The calculation formula is as follows: .

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