Systems and methods for characterizing hydrocarbon-containing fluids

Abstract

A system includes processing circuitry and a non-transitory computer readable medium including instructions to cause the processing circuitry to receive logging data regarding a fluid. The log data is indicative of a plurality of isotope ratios of a plurality of alkanes of the fluid. The instructions also cause the processing circuitry to determine a thermal maturity of the fluid based on at least a first isotope ratio of a plurality of isotope ratios corresponding to log data of a first alkane of the plurality of alkanes. Further, the instructions cause the processing circuitry to determine a gas-to-oil ratio (GOR) of the fluid based on at least a second isotope ratio of the plurality of isotope ratios corresponding to a second alkane of the plurality of alkanes. Further, the instructions cause the processing circuitry to display the thermal maturity of the fluid and the GOR of the fluid.

Description

Technical Field

[0001] The present disclosure generally relates to techniques for analyzing well log data (eg, advanced mud gas log data) to generate data or determinations regarding fluid type, fluid properties, and fluid alteration of petrochemical samples. Background Art

[0002] During the drilling of an oil well or another effluent (particularly gas, steam or water), drilling mud may be brought to the surface. The mud gas may be analyzed to generate data regarding the properties of the gas in the formation (e.g., at different depths in the formation). However, such analysis may be inaccurate because it does not take into account conditions or other considerations that may change the results of such analysis, such as potential fluid alteration, fluid maturity and mixing. Therefore, it is desirable to have an improved method for analyzing hydrocarbon-containing fluids, such as mud gas.

[0003] This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Therefore, it should be understood that these statements should be read in this light, and not as admissions of prior art. Summary of the invention

[0004] The following describes a summary of certain embodiments disclosed herein. It should be understood that these aspects are presented only to provide the reader with a brief overview of these specific embodiments, and these aspects are not intended to limit the scope of the present disclosure. In fact, the present disclosure may include multiple aspects that may not be described below.

[0005] Certain embodiments of the present disclosure include a system that may include a processing circuit and a non-transitory, computer-readable medium, the non-transitory, computer-readable medium including instructions that cause the processing circuit to receive well logging data about a fluid. The well logging data indicates multiple isotope ratios of multiple alkanes of the fluid. These instructions may also cause the processing circuit to determine the thermal maturity of the fluid based on at least a first isotope ratio in the multiple isotope ratios of the well logging data corresponding to the first alkane in the multiple alkanes. In addition, the instructions may cause the processing circuit to determine the gas-oil ratio (GOR) of the fluid based on at least a second isotope ratio in the multiple isotope ratios corresponding to the second alkane in the multiple alkanes. In addition, the instructions may cause the processing circuit to display the thermal maturity of the fluid and the GOR of the fluid.

[0006] Certain embodiments of the present disclosure include non-transitory computer-readable media, which may include instructions for processing circuits to receive well logging data about fluids. Well logging data indicates multiple isotope ratios of multiple alkanes of fluids. In addition, well logging data include multiple amounts. Each corresponding amount in multiple amounts corresponds to the corresponding alkane in multiple alkanes. These instructions also cause processing circuits to determine the thermal maturity of fluids based on at least the first isotope ratio in multiple isotope ratios of well logging data corresponding to the first alkane in multiple alkanes. In addition, instructions cause processing circuits to determine the gas-oil ratio (GOR) of fluids based on at least the second isotope ratio in multiple isotope ratios corresponding to the second alkane in multiple alkanes. In addition, instructions cause processing circuits to determine the gas moisture ratio of fluids based on at least a portion of multiple amounts, determine the fluid type of fluids based on the gas moisture ratio and the first isotope ratio, and cause the thermal maturity of fluids, the fluid type of fluids, and the GOR of fluids to be displayed.

[0007] Certain embodiments of the present disclosure include a computer-implemented method, which may include receiving logging data about a fluid via a processing circuit. The logging data indicates a plurality of isotope ratios of a plurality of alkanes of the fluid. The computer-implemented method may also include determining the thermal maturity of the fluid via the processing circuit and based on at least a first isotope ratio in a plurality of isotope ratios of the logging data corresponding to a first alkane in the plurality of alkanes. In addition, the computer-implemented method may include determining the gas-oil ratio (GOR) of the fluid via the processing circuit and based on at least a second isotope ratio in a plurality of isotope ratios corresponding to a second alkane in the plurality of alkanes. In addition, the computer-implemented method may include making display the thermal maturity of the fluid and the GOR of the fluid via the processing circuit.

[0008] With respect to various aspects of the present disclosure, there may be various improvements of the above-mentioned features. More features may also be incorporated into these different aspects. These improvements and additional features may exist alone or in any combination. For example, the various features associated with one or more of the illustrated embodiments discussed below may be incorporated into any of the above-mentioned aspects of the present disclosure alone or in any combination. The brief overview given above is intended only to familiarize the reader with certain aspects and backgrounds of the embodiments of the present disclosure, and does not limit the subject matter claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various aspects of the present disclosure may be better understood by reading the following detailed description and referring to the accompanying drawings, in which:

[0010] Figure 1 is a schematic diagram of a rotary drilling rig system according to aspects of the present disclosure;

[0011] Figure 2 is a flow chart for characterizing a fluid obtained from a subsurface formation according to aspects of the present disclosure;

[0012] Figure 3 is the isotopic ratio (δ 13 C-C1) and vitrinite reflectance equivalent (VRE);

[0013] Figure 4 is the isotopic ratio (δ 13 C-C2) and VRE curves;

[0014] Figure 5 is according to aspects of the present disclosure 13 Plot of C-C2 versus gas-oil ratio (GOR);

[0015] Figure 6 is a plot of gas humidity ratio versus δ according to aspects of the present disclosure 13 C-C1 and providing a graph of an area of ​​potential characteristics of a fluid sample based on placement of data points of the sample within the graph;

[0016] Figure 7 A chart according to aspects of the present disclosure includes several sections having graphs indicating characteristics of a well or a subterranean formation, the graphs being able to be represented by Figure 1 The data analysis system of the rotary drilling rig system is generated;

[0017] Figure 8 is a plot of gas humidity ratio versus δ according to aspects of the present disclosure 13 A graph of C-C2; and

[0018] Fig. 9 is a drawing characteristic (character) and δ according to various aspects of the present disclosure 13 C-C2 curve diagram. DETAILED DESCRIPTION

[0019] One or more specific embodiments will be described below. In order to provide a concise description of these embodiments, not all features of the actual implementation are described in the specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, many implementation-specific decisions must be made to achieve the developer's specific goals, such as complying with system-related and enterprise-related constraints, which may vary from implementation to implementation. In addition, it should be understood that such development efforts may be complex and time-consuming, but for ordinary technicians who benefit from this disclosure, this is still a routine task of design, fabrication and manufacturing.

[0020] When introducing elements of various embodiments of the present disclosure, the articles "a," "an," and "the" are intended to indicate that there are one or more elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements in addition to the listed elements. Furthermore, it should be understood that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0021] As used herein, the terms “connect,” “connection,” “connected,” “in connection with,” and “connecting” are used to mean “directly connected with” or “connected with via one or more elements,” and the term “group” is used to mean “one element” or “more than one element.” In addition, the terms “couple,” “coupling,” “coupled,” “coupled together,” and “coupled with” are used to mean “directly connected together” or “coupled together via one or more elements.”

[0022] Additionally, as used herein, the terms "real-time," "real-time," or "substantially real-time" may be used interchangeably and are intended to describe operations (e.g., computing operations) that are performed without any human-perceivable interruptions between operations. For example, as used herein, data associated with the systems described herein may be collected, transmitted, and / or used in control calculations in "substantially real-time," such that data reading, data transmission, and / or data processing steps occur once per second, once every 0.1 seconds, once every 0.01 seconds, or even more frequently during operation of the system (e.g., while the system is operating). Additionally, as used herein, the terms "automatic" and "automated" are intended to describe operations that are performed, such as by the analysis system alone, without human intervention.

[0023] The present disclosure relates to the characterization of fluid or gas (e.g., mud gas) samples. In particular, the presently described techniques are capable of automatically converting advanced mud gas logging data into information about fluid type, fluid properties, and fluid alteration. Specifically, the delta 13 The C value can be used to determine thermal maturity (eg, converted to vitrinite reflectance equivalent (VRE)) and gas-oil ratio (GOR).

[0024] In stable isotope geochemistry, stable carbon isotopes can be expressed as 13 C and 12C ratio relative to an international reference material. For example, this isotopic ratio of methane (C1) (e.g., δ 13 C value) can be expressed as δ 13 C-C1. Delta of gaseous alkanes 13 C values ​​can be used to interpret fluid maturity, fluid type, and fluid alteration. 13 The expected range of C values ​​is usually -80 to -20‰ or parts per thousand for methane, -45 to -20‰ for ethane (C2), and -45 to 0‰ for propane (C3). Although in general, δ 13 C values ​​increase with increasing thermal maturity, but alteration processes can affect these values. For example, biodegradation produces biogenic methane, which has negative values, typically below -60‰, while thermogenic methane covers a range of about -55 to -20‰. In addition, biodegradation can result in δ 13 C increases. In many cases, in sedimentary basins, background biogenic methane is present from early depositional stages. At later stages, thermogenic hydrocarbons may combine or mix with biogenic methane. Therefore, isotopic analysis of alkanes such as methane, ethane, and propane can be useful in determining the maturity of charge and alteration scenarios, whereas analysis of methane alone may not be sufficient. More specifically, mature gas recharge may occur in reservoirs with less mature fluids (e.g., black oil), which may affect gas-based interpretations of the reservoir. As discussed herein, δ 13 Well logging enables characterization of active hydrocarbon systems, for example, determining fluid maturity distribution, gradients and mixing, distinguishing thin-bed reservoirs, and predicting fluid properties.

[0025] However, in contrast to isotopic composition, mud gas molecular composition is susceptible to the influence of mud gas degassing techniques. Specifically, factors of this vulnerability are: 1) mud gas extraction efficiency (depending on mud type, temperature and density, which control gas solubility and extractability); 2) mud gas recovery in reused drilling mud; and 3) degassing techniques. These factors can affect the molecular gas ratio because alkanes have different properties and can be fractionated in the C1-C5 range (i.e., methane, ethane, propane, butane and pentane). As described below, isotope logging data can be used as a proxy for, for example, determining the properties and characteristics of underground fluids (e.g., mud gas). Although the currently disclosed technology may be described below as being performed in conjunction with advanced mud gas logging (AMGL), the currently disclosed technology can be used with any isotope logging system or technology.

[0026] Figure 1is a schematic diagram of an example embodiment of a rotary drilling system 5. Downhole measurements may be made by instruments disposed in a drill collar 20. Such measurements may be stored in a storage device of the downhole instrument, or may be telemetered and sent to the surface by conventional measurement while drilling (MWD) telemetry devices and techniques. To this end, an MWD tool joint, schematically shown as tool 29, may receive signals from the instrument of the drill collar 20 and may transmit these signals via a mud path 8 of a drill string 6 for reception, for example, ultimately via a pressure sensor 14 in a riser 15 and / or to other surface instruments 7.

[0027] The drilling system 5 may include a motor 2 that can rotate the kelly 3 using a rotary table 4. The drill string 6 may include drill rod sections connected end-to-end to the kelly 3 and may be rotated thereby. For example, drill collars and / or tools 20, 26, 28, and 29 may be attached to the drill string 6. Such drill collars and tools may together form a bottom hole assembly (BHA) 50 extending from the drill string 6 to the drill bit 30. As the drill string 6 and the BHA 50 rotate, the drill bit 30 may drill a wellbore 9. Thus, an annulus 10 is defined between the exterior of the drill string 6 (including the BHA 50) and the wellbore 9 by one or more underground geological formations 32.

[0028] A pump 11 may pump drilling fluid (drilling "mud") from a source, such as a mud pit 13, to the drill bit 30 via a riser 15, a rotary injection head 17, and a mud path 8 of the kelly 3 and drill string 6. The mud, which may be a water-based or oil-based drilling mud, may lubricate the drill bit 30 and may carry wellbore cuttings upward to the surface through the annulus 10. If desired, the mud may be returned, for example, to the mud pit 13 or a suitable mud regeneration location, where it may be separated from the cuttings, etc., degassed, and returned for reapplication to the drill string 6.

[0029] A shale shaker 52 can separate the drill cuttings from the mud. Once the mud and drill cuttings are separated, the mud and drill cuttings can be collected and analyzed. Cuttings samples 54 can be collected manually and analyzed in a mud logging cabin using one or more instruments (e.g., microscope, X-ray fluorescence (XRF), X-ray diffraction (XRD), etc.). Alternatively, cuttings samples can be automatically collected and analyzed at the well site.

[0030] The drilling fluid (e.g., drilling mud) can be sampled by a sampling device 56 at the outlet of the vibrator 52 and directed to an extractor 58, which extracts gas from the drilling mud. The gas is then directed to an analyzer 60 to detect the content of the gas. In other words, the analyzer 60 can generate logging data (e.g., a data stream) about the (mud) gas. The analyzer 60 can include a thermal conductivity detector (TCD), a flame ionization detector (FID), and / or a mass spectrometer. The analyzer can also include a gas chromatograph (GC). The analyzer 60 may also be a device capable of producing logging data indicative of the isotopes (and (relative) amounts) of carbon in the mud gas. For example, the analyzer 60 may perform GC-oxidation reactor-isotope ratio mass spectrometry (GC-ox-IRMS). The analyzer 60 may also include a GC-ox-hollow waveguide-quantum cascade (HWG-QC) IR laser (GC-ox-HWG-IR) or any other GC-ox analyzer system. The analyzer 60 may also be or include a device capable of performing advanced mud gas logging (AMGL), which may involve control of extraction thermodynamics and correction of extraction efficiency and mud gas recirculation bias. Thus, the analyzer 60 may be or include any device capable of producing isotope logging data regarding the gas extracted from the drilling fluid.

[0031] It should be noted that the techniques of the present application can be used on samples analyzed in other ways. For example, isotope laboratory analysis of mud gas point samples (e.g., isotope tubes (IsoTube), vacuum bottles (Vacutainers), gas bottles or gas bags) or even bottom hole sample (BHS) solution gases using GC-ox-IRMS can also be used. The gas molecular composition data can come from any source of alkanes (e.g., C1-C5) of the same or similar frequency, for example, mud logging gas chromatography (GC), or gas chromatography on an isotope analyzer gas chain, or laboratory analysis of point samples. Therefore, the techniques currently described can be used for logging data, regardless of whether the logging data is generated on-site (e.g., on the ground or downhole) or off-site (e.g., in a laboratory environment).

[0032] The downhole tool (drill collar) 20 may be any type of downhole tool that performs measurements, such as an ultrasonic tool, an electromagnetic or resistivity tool, a sampling tool. For example, the ultrasonic tool may include at least one or more sensors 45, 46, for example, for measuring properties of the wellbore 9 and / or fluid, including pressure, clearance, composition, etc. therein during drilling operations. Such measurements may be performed while the wellbore 9 is being drilled, and / or while the drill bit 30, BHA 50, and drill string 6 are not rotating, while the drill string 6 and BHA 50 are in the wellbore 9. Such measurements may be performed while the drill string 6, BHA 50, and drill bit 30 are being tripped to and from the bottom of the wellbore 9. The measurements (or data based at least in part on the measurements) may be transmitted to the surface via the MWD telemetry tool 29 and the internal mud passage 8 of the drill string 6 (or annulus 10), or they may be recorded and stored downhole and retrieved at the surface after the drill string 6 and BHA 50 are removed from the wellbore 9.

[0033] The sensors 45, 46 may be mounted on the stabilizing fins 27 of the downhole tool 20, such as Figure 1 As shown, or may be mounted in the cylindrical wall 23 of the downhole tool 20. The electronic module 22 may include electronic circuitry, a microprocessor, a memory and / or the like, operable to control and / or receive, process and / or store data from sensors 45, 46, which may be mounted on a sleeve, inner tube and / or other portion 21 secured around or within a collar of the downhole tool 20. The portion 21 of the BHA 50 and other components may include a path 40 through which drilling mud may pass through the internal passage 8 of the drill string 6 to the drill bit 30.

[0034] A part of the drilling system 5, such as the surface instrument 7, may include other sensors for measuring parameters at the surface, such as flow, pressure, bit pressure, bit torque, etc., and verifying that the drilling system 5 is functioning properly. As an example, a sensor 61 may be connected to the pump 11 to count the number of strokes of the pump, and a sensor 62 may be present at the kelly 3 or the motor to evaluate the revolutions per minute (RPM) or bit pressure and bit torque.

[0035] The surface instrumentation 7 may also include a data processing system 64, which may include one or more of the following or portions thereof: control devices and electronics (e.g., downhole controllers) in one or more modules of the BHA 50, a remote computer system (not shown), communications equipment, and other equipment. The data processing system may include one or more computer systems or devices, and / or may be a distributed computer system. For example, the collected data or information may be stored, distributed, transmitted to a human wellsite operator, and / or processed locally or remotely.

[0036] The data processing system 64 may also be linked to all or part of the sensors downhole or at the surface, either alone or in combination with other system components, to process the measurements, and may perform the methods and / or processes described below, or portions thereof. For example, the data processing system 64 may include processor capabilities for collecting data obtained from sensors at the surface or downhole. The methods and / or processes within the scope of the present disclosure may be implemented by one or more computer programs running in a processor, such as one or more modules of the BHA 50 and / or surface equipment of the drilling rig system 5, and / or a remotely located processing system that is communicatively coupled to the BHA 50 of the drilling rig system 5 (e.g., via a wired or wireless connection). Such a program may utilize data received from the BHA 50 via mud pulse telemetry and / or other telemetry means, and / or may transmit control signals to operating elements of the BHA 50. The program may be stored on a tangible, non-transitory, computer-usable storage medium associated with one or more processors of the BHA 50 and / or surface equipment (e.g., surface instrumentation 7) of the drilling rig system 5, or may be stored on an external tangible, non-transitory, computer-usable storage medium electrically coupled to such processors. The storage medium may be one or more known or future developed storage media, such as a magnetic disk, an optically readable disk, a flash memory, or another readable device, including a remote storage device coupled via a communication link, among other examples. Thus, the data processing system 64 may include a processing circuit (e.g., one or more processors) communicatively coupled to one or more non-transitory computer-readable media capable of storing instructions (e.g., in the form of an application or program) that the processing circuit may execute. The one or more non-transitory computer-readable media may be included in the data processing system 64, or communicatively coupled to the processing circuit of the data processing system. Thus, the data processing system 64 may receive data about mud gas or other gases being analyzed (e.g., well logging data such as isotope logging data) from the analyzer 60 and, utilizing processing circuitry executing instructions stored on one or more non-transitory computer-readable media, analyze the well logging data to make determinations about mud gas and / or control one or more components of the rig system 5, such as the analyzer 60 or the BHA 50. That is, it should be noted that in other embodiments, the techniques described herein as being performed by the data processing system 64 may be performed by, for example, a remote computing device or system that receives data from the analyzer 60. Furthermore, it should be noted that the data processing system 64 may include and / or be communicatively coupled to one or more displays. Thus, the data processing system 64 may also cause data or representations of data to be displayed.

[0037] As mentioned above, the present disclosure relates to the characterization of fluid or gas (e.g., mud gas) samples. In particular, the presently described techniques are capable of automatically converting advanced mud gas logging data into information about fluid type, fluid properties, and fluid alteration. Specifically, the delta 13 The C value can be used to determine thermal maturity (eg, converted to vitrinite reflectance equivalent (VRE)) and gas-oil ratio (GOR).

[0038] Continue with the attached picture, Figure 2 1 is a flow chart of a process 100 for characterizing subsurface formations and subsurface formation fluids. Process 100 may be performed by processing circuitry executing instructions stored on a computer-readable medium, such as processing circuitry of data processing system 64. However, while the operations of process 100 are discussed below as being performed by data processing system 64, it should be noted that process 100 may be performed by processing circuitry that is communicatively coupled to analyzer 60 or configured to receive logging data, such as isotope logging data. Additionally, while the operations of process 100 are discussed below in one order, it should be noted that in other embodiments, the operations of process 100 may be performed in another order and / or omitted. With this in mind, process 100 generally includes receiving isotope logging data for a sample (e.g., mud gas) (process block 102), using delta values ​​of the isotope logging data to determine the isotope logging data. 13 C (can also be written as "d 13 C”) value to determine the thermal maturity of the sample (process block 104), based on δ 13 C-C2 determines the gas-oil ratio (GOR) of the sample (process block 106), based on humidity and delta 13 C-C1 characterizes the sample (process block 108), determines whether the sample is of purely thermogenic origin (decision block 110), and when it is determined that the sample is not of purely thermogenic origin, uses δ 13 C-C1 and humidity determine the fraction of biogenic methane (process box 112), and use the added fraction of biogenic methane to correct the GOR and indicate the amount of mixing of the sample (process box 114). Process 100 may also include evaluating the biodegradation of the sample (process box 116) and indicating the severity of biodegradation (process box 118). In addition, process 100 may include evaluating δ 13 C-C1, δ 13 C-C2 and δ 13The process 100 may include determining the difference between C-C3 (process box 120), determining whether the sample has a thermogenic gas recharge (decision box 122), and when it is determined that the sample has a thermogenic gas recharge, determining a thermogenic recharge modifier for the GOR (process box 124), and adjusting the GOR for the thermogenic gas recharge and indicating the severity of the thermogenic gas recharge (process box 126). In addition, the process 100 may include indicating the GOR and the associated fluid type (process box 128), which may be done after process box 106, after process box 114, after process box 126, when it is determined that the sample is of a purely thermogenic origin (e.g., at decision box 110), or when it is determined that there is no thermogenic gas recharge (e.g., at decision box 122).

[0039] At process block 102, processing circuitry of data processing system 102 may receive well logging data (also referred to as "well logging data") for a sample. For example, well logging data regarding mud gas may be generated by analyzer 60 (e.g., after being extracted from drilling mud by extractor 58). More specifically, the well logging data may include delta olefins, olefins, and hydrocarbons. 13 C value isotope logging data. For example, in one embodiment, δ 13 The C value can include δ 13 C-C1 (for methane) and δ 13 In another embodiment, δ 13 The C value may additionally include δ 13 C-C3 value (for propane). In yet another embodiment, δ 13 The C value can also include δ 13 C-C4 (butane) and delta 13 Values ​​for C-C5 (pentane). Well log data may also include data indicating the (relative) amounts of different alkanes in the sample and / or the moisture ratio of the gas.

[0040] At process block 104, the data processing system may use the delta of the well logging data received at process block 102 to 13 C value to determine the thermal maturity of the sample. In particular, the data processing system 64 can determine the maturity of the sample based on several alkanes, such as methane, ethane, and propane. Therefore, multiple thermal maturity can be determined at process block 104. The thermal maturity can be reflected by a value (e.g., a percentage) of vitrinite reflectance equivalent (VRE). The data processing system 64 can be based on δ 13 More specifically, the data processing system 64 can calculate the VRE value of an alkane by converting δ 13 The C value is converted into the CRE value to determine the VRE value. For example, Figure 3 is δ 13A graph 150 of C-C1 (shown as axis 152) versus VRE (shown as axis 154). Graph 150 includes a graph for converting the delta 13 Line 156 of the polynomial equation for converting C-C1 to VRE of methane. As another example, Figure 4 is δ 13 A graph 170 of C-C2 (shown as axis 172) versus VRE (shown as axis 174) is provided, and graph 170 includes a graph for converting δ 13 Line 176 of the polynomial equation for converting C-C2 to the VRE of ethane. 13 The polynomial equation for converting C values ​​to VRE values ​​can be of third, fourth, or fifth order. In other words, the highest exponent included in the equation can be three, four, or five. In addition, the polynomial equation can be derived from the delta 13 The VRE modeling of C is derived from work such as U. Berner and E. Faber, “Empirical carbon isotope / maturity relationships for gases from algal kerogens and terrigenous organic matter, based on dry, open-system pyrolysis”, Organic Geochemistry, Vol. 24, No. 10-11, pp. 947-955. In addition, the polynomial equations can be adjusted to cover the δ 13 For example, in graph 150, for methane, VRE can be calculated from -48‰ to -25‰, which corresponds to the lowest measurable vitrinite reflectance (Ro) of about 0.3% (e.g., the least mature source rock at the very beginning of hydrocarbon generation) and high maturity wells (e.g., dry gas), respectively. For ethane, as shown by line 176 in graph 170, for δ 13 The polynomial equation can return VRE values ​​ranging from 0.3% to 2.15% for C-C2 values. In addition, for propane, for δ 13 C-C3 values, VRE values ​​ranging from -36.5‰ to -24.45‰ can be determined.

[0041] At process block 106, the data processing system 64 may calculate the sample's delta based on the sample's delta. 13 The C-C2 value determines the gas oil ratio (GOR) of the sample. To determine the GOR, the data processing system 64 may utilize the 13 The equation for converting C-C2 value into GOR. For example, Figure 5 Is to draw δ 13A graph 180 of C-C2 (shown as axis 182) versus GOR (shown as axis 184) is shown, wherein line 186 represents the value for converting δ 13 The equation for converting the C-C2 value into the GOR value. The equation may be a natural exponential equation (e.g., an equation in which a constant is multiplied by an exponential value of e, which may include δ 13 C-C2 value or derived therefrom). In graph 180, axis 184 is logarithmic, and various portions 188 (collectively referred to as portions 188A-188F) of line 186 correspond to fluid types. Portions 188 may include portion 188A (corresponding to dry gas), portion 188B (corresponding to wet gas), portion 188C (corresponding to condensate), portion 188D (corresponding to co-origin with volatile oil), portion 188E (corresponding to co-origin with peak oil), and portion 188F (corresponding to co-origin with early oil). Thus, data processing system 64 may select a sample based on its delta-value. 13 The C-C2 value determines the GOR of the sample.

[0042] Return to reference Figure 2 Continuing with the discussion of process 100, at process block 108, the data processing system 64 may calculate the relative humidity (eg, gas humidity ratio) and delta 13 The data processing system 64 may receive the gas humidity ratio as part of the well log data received at process block 102, or determine the gas humidity ratio from values ​​of the received well log data indicating the amounts of different alkanes in the sample (e.g., parts per million (PPM)). For example, the data processing system 64 may determine the gas humidity ratio by determining a first sum of the amounts of ethane, propane, butane, and pentane in the sample, determining a second sum of the amounts of methane, ethane, propane, butane, and pentane in the sample, and dividing the first sum by the second sum (and optionally multiplying the quotient by 100 to produce a percentage ratio).

[0043] In order to 13 C-C1 to characterize the sample, the data processing system 64 can determine the given humidity and δ 13 The range or region into which C-C1 falls (e.g., as indicated by Figure 6 In particular, Figure 6 is to plot humidity (e.g., gas humidity ratio, as shown on axis 202) versus δ 13Graph 200 also includes regions 206 (collectively, regions 206A-206I). Regions 206 corresponding to fluid types may include region 206A (corresponding to pure biogenic methane), region 206B (corresponding to a mixture dominated by biogenic), region 206C (corresponding to a mixture dominated by thermogenic), region 206D (corresponding to dry gas), region 206E (corresponding to wet gas), region 206F (corresponding to condensate), region 206G (corresponding to co-genesis with volatile oil), region 206H (corresponding to co-genesis with peak oil), and region 206I (corresponding to co-genesis with early oil). Some regions 206 may correspond to Figure 5 188B, region 206F corresponds to portion 188C, region 206G corresponds to portion 188D, region 206H corresponds to portion 188E, and region 206I corresponds to portion 188F. Thus, region 206 corresponds to a fluid type. Graph 200 or data representing or indicative of graph 200 may be stored in a computer readable medium and used by data processing system 64 to perform the operations of process block 206. In practice, to characterize a sample, data processing system 64 may characterize a sample based on the gas humidity ratio of the sample and the delta of the sample. 13 The C-C1 value determines which region 206 the sample falls into.

[0044] Back to Figure 2 As discussed with respect to process 100, at decision block 110, the data processing system 64 may determine whether the sample is of purely thermogenic origin, for example, based on the characterization performed at process block 108. More particularly, with reference to Figure 6 Once it is determined that the sample falls within region 206D, region 206E, region 206F, region 206G, region 206H, or region 206I of graph 200, data processing system 64 may determine that the sample is of pure thermogenic origin. In other words, if the sample is based on the gas humidity ratio and δ 13 C-C1 adds a point to the graph 200, and the point is located in one of the regions 206D-206I, the data processing system 64 may determine that the sample is of purely thermogenic origin. Conversely, upon determining that the point is outside of one of the regions 206D-206I, the data processing system 64 may determine that the sample is not of purely thermogenic origin. For example, if the point is located inside of the region 206A, the region 206B, or the region 206C, the data processing system 64 may determine that the sample is not of purely thermogenic origin. As described below, the GOR of the sample (e.g., as determined at process block 106) may be corrected based on determining that the sample is not of purely thermogenic origin.

[0045] Back to Figure 2 As discussed with respect to process 100, if at decision block 110 the data processing system 64 determines that the sample is not of purely thermal origin, then at process block 112 the data processing system 64 may determine based on the sample's δ 13 C-C1 and the gas humidity ratio determine the fraction of biogenic methane in the sample. To determine the fraction of biogenic methane, the data processing system 64 can determine a value associated with the distance from the trend line 230 of the graph 200 at which the point of the sample would be when plotted on the graph 200. More specifically, the fraction of biogenic methane can be determined by determining the quotient of the difference divided by the sum, where the difference is calculated by subtracting δ from a value 13 C-C1 is determined, and is determined by adding the value to a constant. The constant can be an integer (e.g., a value between 50 and 100, including 50 and 100), and the value can be determined based on the gas humidity ratio of the sample. More specifically, the value can be determined using a quadratic polynomial equation, in which a first constant (e.g., a value between 0.001 and 0.01, including 0.001 and 0.01) is multiplied by the square of the gas humidity ratio to obtain a first value. The second value is subtracted from the first value to obtain a third value. The second value can be determined by multiplying the gas humidity ratio by a second constant (e.g., a value between 0 and 1, including 0 and 1). Finally, a third constant (e.g., a value between 10 and 50, including 10 and 50) is subtracted from the third value to obtain the fraction of biogenic methane.

[0046] At process block 114, data processing system 64 may correct the GOR (e.g., as determined at process block 106) based on the fraction of biogenic methane determined at process block 112. In one embodiment, to correct the GOR, data processing system 64 may multiply the GOR (as determined at process block 106) by a value that is the inverse of the difference between the fraction of biogenic methane determined at process block 112. In this way, data processing system 64 may correct the determined GOR to account for the sample not being of a purely thermogenic origin.

[0047] At process block 114, the data processing system 64 may additionally indicate the amount of mixing based on the fraction of biogenic methane determined at process block 112. For example, the data processing system 64 may cause a visual representation to be displayed indicating the degree of mixing in the sample. Such a visual representation may be a graph or included in the graph.

[0048] Reference again Figure 2Continuing with the discussion of process 100, at process block 116, the data processing system 64 may assess biodegradation of the sample, for example, based on the thermal maturity of the sample (e.g., as determined at process block 104). Biodegradation may be a significant alteration of the original petroleum fluid, oil, or natural gas, resulting in overall compositional changes that affect fluid properties such as viscosity and flowability. Biodegradation also adds its product, biogenic methane, to the fluid, which increases the GOR. Thus, the data processing system 64 may assess biodegradation to determine the extent or severity of biodegradation, if any. In one embodiment, the data processing system 64 may assess biodegradation of the sample by determining the presence of a number of conditions. These conditions may include, for example: 1) based on δ 13 C-C3 determined VRE and based on δ 13 The difference between the VRE determined by C-C2 exceeds a threshold value (e.g., a value between 0 and 0.5, inclusive); 2) the amount ratio of isobutane to butane in the sample (e.g., as shown in the received well logging data) is greater than 1; 3) the amount ratio of isopentane to pentane in the sample (e.g., as shown in the received well logging data) is greater than 1; 4a) δ 13 The value of C-C3 is less than -49, or 4b) if δ 13 The value of C-C3 is greater than -49, then based on δ 13 C-C2 determined VRE and based on δ 13 The difference in VRE determined by C-C1 exceeds a threshold value (which may be the same as the threshold value used in the first condition); 5) δ 13 The C-C3 value exceeds -22; and 6) a ratio that exceeds another threshold value (e.g., between 0 and 0.5, inclusive), wherein the ratio is a ratio of a first value (e.g., a ratio of the amount of ethane to propane in the sample (e.g., as indicated by the received logging data)) to a second value, which can be a ratio of the amount of ethane to isobutane in the sample (e.g., as indicated by the received logging data).

[0049] At process block 118, the data analysis system 64 may indicate the severity of the biodegradation, for example, by causing a graphical representation of the number of conditions present (and / or an indication of which conditions are present) discussed above with respect to process block 116. For example, Figure 7 2 is a graph 250 including a portion 252 (collectively referred to as portions 252A-252G). Portion 252A includes a graph 254 having an axis 256 (indicating a reference point, such as a point indicating when mud gas was analyzed or from where (e.g., depth) mud gas was collected and analyzed) and an axis 258 indicating the relative position of the mud gas based on delta. 13The VRE determined at the reference point C-C1 is determined. The various portions of the graph 254 indicate the thermal maturity at various reference points along axis 256 (e.g., for which the sample was analyzed), as indicated by the various shades or hatchings. Portion 252B includes a graph having axis 256 and axis 262 (representing the thermal maturity of the sample based on δ 13 C-C2 determined at the reference point) graph 260, which, like graph 254, represents thermal maturity at various reference points along axis 256. Somewhat similarly, portion 252C includes graphs having axis 256 and axis 266 (indicating the thermal maturity of the VRE determined at the reference point based on δ 13 C-C3 determined at reference points) graph 264, which is similar to graph 254, indicates the thermal maturity of various reference points along axis 256. Section 252D includes graph 268, which indicates the thermal maturity of various reference points based on Figure 6 252F includes a graph 274 having axis 256 and axis 276, which indicates the severity of biodegradation (also indicated by shading or hatching). Section 252G includes a graph 278, which indicates the thermogenic gas charge (e.g., mature gas charge) as indicated along axis 280 (and by shading or hatching) for a particular reference point (indicated along axis 256). Thus, to indicate the severity of biodegradation, data analysis system 64 may generate and cause graph 274 to be displayed in process block 118. In some embodiments, the operations of process block 116 may be performed simultaneously with the operations associated with process block 122 or process 124 discussed below.

[0050] Back to Figure 2 As discussed with process 100, at process block 120, data processing system 64 may evaluate differences between isotopic ratios of, for example, methane, ethane, and propane to assess thermogenic gas charge, which may also be referred to as "mature gas charge." In many reservoirs, less mature fluids (e.g., hydrocarbons) are followed by more mature fluids, typically gases, as a result of increasing burial depths due to the accumulation of sediments in a basin (e.g., a deltaic system), which in turn causes an increase in the temperature of the underlying source rock. This later arriving, more thermally mature gas has a "heavier" rich 13C isotopic signature. When mixed with low maturity fluids (such as black oil associated gas), this will result in a higher VRE for the lighter gas, which is more concentrated in the mature gas. As a result, the expected pattern in the mixture is based on the δ 13 C-C1 determined VRE (VRE C1 ) will be greater than based on δ 13 C-C2 determined VRE (VRE C2 ), which will be greater than the 13 C-C1 determined VRE (VRE C3 The data processing system 64 may take into account the amount of excess VRE (eg, due to thermogenic gas replenishment) for all three pairs of C1 , C2 , and C3 .

[0051] In practice, to assess the thermogenic gas charge, at process block 120, the data processing system 64 may determine whether any of the following conditions exist: 1a) Based on δ 13 VRE determined by C-C1 and based on δ 13 The difference between the VREs determined in C-C2 exceeds or is equal to a first threshold value (e.g., a value between 0 and 0.5, inclusive), which may indicate a relatively high degree of thermogenic gas replenishment (compared to 1b); 1b) when the difference determined in 1a is less than the first threshold value, the difference exceeds a second threshold value that is less than the first threshold value; 2a) based on δ 13 VRE determined by C-C1 and based on δ 13 The difference between the VREs determined at C-C3 exceeds or is equal to a first threshold (e.g., the same threshold used in 1a), which may indicate a relatively high degree of thermogenic gas replenishment (compared to 2b); 2b) when the difference determined at 2a is less than the first threshold, the difference exceeds a second threshold (e.g., the same second threshold used above in 1b) that is less than the first threshold; 3a) based on δ 13 C-C2 determined VRE and based on δ 13 The difference between the VREs determined by C-C3 exceeds or is equal to a first threshold (e.g., the same threshold used in 1a), which may indicate a relatively high degree of thermogenic gas replenishment (compared to 3b); and 3b) when the difference determined in 3a is less than the first threshold, the difference exceeds a second threshold (e.g., the same second threshold used above in 1b) that is less than the first threshold. Each time the first threshold is exceeded (or equal to) a determined difference, the data processing system 64 may assign a degree or severity of mature gas replenishment that is greater than (e.g., twice) the degree or severity assigned when the first threshold is not exceeded (or equal to) but the second threshold is exceeded. When either threshold is exceeded (or, in the case of the first threshold, equal to), the data processing system 64 may determine that thermogenic gas replenishment is present.

[0052] At decision block 122, the data processing system 64 may determine whether the sample has a thermogenic gas supply based on the difference evaluated in process block 120. For example, the data processing system 64 may determine that a thermogenic gas supply is present when the first threshold or the second threshold described in the preceding paragraph is exceeded (or, in the case of the first threshold, is equal to).

[0053] If at decision block 122, the data processing system 64 determines to adjust the GOR (e.g., based on determining that thermogenic gas replenishment is present), then at process block 126, the data processing system 64 may determine a thermogenic gas replenishment correction amount for the GOR based on the extent or severity of the thermogenic gas replenishment (e.g., as determined at process block 106 or process block 114). The thermogenic gas replenishment correction amount may be determined as a quotient of an integer value representing the determined severity of thermogenic gas replenishment divided by an integer representing the maximum possible severity of thermogenic gas replenishment. The integer representing the maximum possible severity of thermogenic gas replenishment may be such that thermogenic gas replenishment may occur when the first threshold value (described in the two paragraphs above) is exceeded or equal to each of the three difference values ​​described in the two paragraphs above.

[0054] At process block 126, the data processing system 64 may correct the GOR based on the thermogenic gas replenishment correction amount. For example, the data processing system 64 may multiply the determined GOR (e.g., the GOR determined at process block 106 or the GOR corrected at process block 114, if applicable) by the sum of 1 and the thermogenic gas replenishment correction amount. Thus, the GOR may be corrected to account for the extent or severity of thermogenic gas replenishment in the sample. Additionally, also at process block 126, the data processing system 64 may indicate the severity of thermogenic gas replenishment. More specifically, the data processing system 64 may cause the extent of thermogenic gas replenishment (or a representation thereof) to be displayed, for example, as a value or in the form of a graph 278.

[0055] At process block 128, data processing system 128 may indicate the GOR of the sample and the associated fluid type. For example, data processing system 64 may cause the GOR (or a representation of the GOR (as determined at process block 106 or as modified at process block 114 or process block 126), which may be included in graph 270, to be displayed alone or in conjunction with an indication of the fluid type of the sample (e.g., value or graph 268). It should also be noted that when performing the operations of process block 128, data processing system 64 may cause graph 250 or any portion 252 thereof to be displayed. The operations of process block 128 may be performed after determining the GOR (e.g., at process block 106), in response to determining that the sample is of purely thermogenic origin (e.g., at decision block 110), determining that the sample has no thermogenic gas supply (e.g., at decision block 122), or after modifying the GOR (e.g., at process block 114 or process block 126).

[0056] In other embodiments, the process 100 may include operations in addition to the operations described above. For example, in response to characterizing the sample as being of pure thermogenic origin (or not pure thermogenic origin), determining the presence or possible presence of biodegradation, determining the presence or possible presence of thermogenic gas replenishment, or any combination thereof, the data processing system 64 may change the sampling rate, change the position of the BHA 50, change the rate at which the BHA 50 (or a portion thereof) traverses the subsurface geological formation 32, or any combination thereof. For example, in one embodiment, the data processing system 64 may decrease the sampling rate of mud gas in response to determining that the sample is of pure thermogenic origin or in response to determining that the sample is not of pure thermogenic origin. In another embodiment, the data processing system 64 may increase the sampling rate of mud gas in response to determining that the sample is of pure thermogenic origin or in response to determining that the sample is not of pure thermogenic origin. As another example, in response to determining the presence of biodegradation and / or in response to determining the presence of thermogenic gas replenishment, the data processing system 64 may decrease the sampling rate of mud gas. As yet another example, in response to determining that biodegradation is present and / or in response to determining that thermogenic gas replenishment is present, the data processing system 64 may increase the sampling rate of the mud gas.

[0057] In another embodiment, the data processing system 64 may raise or lower the position of the BHA 50, increase or decrease the rate at which the BHA 50 traverses the subterranean geological formation 32, or both, in response to determining that the sample is of purely thermogenic origin or in response to determining that the sample is not of purely thermogenic origin. In yet another embodiment, the data processing system 64 may raise or lower the position of the BHA 50, increase or decrease the rate at which the BHA 50 traverses the subterranean geological formation 32, or both, in response to determining that biodegradation is present and / or in response to determining that thermogenic gas replenishment is present. As yet another example, the data processing system 64 may raise or lower the position of the BHA 50, increase or decrease the rate at which the BHA 50 traverses the subterranean geological formation 32, or both, in response to determining that biodegradation is present and / or in response to determining that thermogenic gas replenishment is present.

[0058] As follows about Figure 8 and Fig. 9 As described above, the technology of this application can also use δ 13 C-C2 and two different ratios as surrogates for thermal maturity enable characterization (e.g. fluid maturity). In particular, Figure 8 is to plot the gas humidity ratio (as shown on axis 302) versus δ 13 C-C2 (as shown on axis 304) is a graph 300. Graph 300 also includes graphs corresponding to Figure 5 Region 306 (collectively, regions 306A-306F) corresponds to regions 206D-206I of graph 200. For example, portion 306A corresponds to region 206D, portion 306B corresponds to region 206E, portion 306C corresponds to region 206F, portion 306D corresponds to region 206G, portion 306E corresponds to region 206H, and portion 306F corresponds to region 206I. Fig. 9 is to plot the gas properties (shown as axis 322) versus δ 13 The data analysis system 64 may determine the value of the gas property by dividing the total amount of butane and pentane in the sample by the amount of propane in the sample. The graph 320 also includes a graph corresponding to Figure 5 The data processing system 64 may include regions 326 (collectively, regions 326A-326F) corresponding to regions 206D-206I of the graph 200. For example, portion 326A corresponds to region 206D, portion 326B corresponds to region 206E, portion 326C corresponds to region 206F, portion 326D corresponds to region 206G, portion 326E corresponds to region 206H, and portion 326F corresponds to region 206I. The data processing system 64 may characterize a sample based on which of the regions 306, 236 the data points of the sample are located.

[0059] In one embodiment, system comprises processing circuit and non-transitory computer readable medium, and this non-transitory computer readable medium comprises instruction, and this instruction, when being executed by processing circuit, makes processing circuit receive the multiple isotope ratio of multiple alkanes of fluid.The multiple isotope ratio of multiple alkanes of well logging data indication fluid is indicated.When being executed, described instruction also makes processing circuit determine the thermal maturity of fluid based on at least the first isotope ratio in the multiple isotope ratio of the well logging data corresponding to the first alkane in multiple alkanes.In addition, when being executed, instruction makes processing circuit determine the gas-oil ratio (GOR) of fluid based on at least the second isotope ratio in the multiple isotope ratio corresponding to the second alkane in multiple alkanes.In addition, when being executed, instruction makes display the thermal maturity of fluid and the GOR of fluid.

[0060] The well logging data may include a plurality of quantities, wherein each respective quantity in the plurality of quantities corresponds to a respective alkane in the plurality of alkanes. In addition, when executed, the instructions may further cause the processing circuit to determine a gas moisture ratio of the fluid based on at least a portion of the plurality of quantities, and determine a thermal maturity of the fluid based on the gas moisture ratio.

[0061] The instructions, when executed, may further cause the processing circuit to determine the GOR based on at least the second isotope ratio and determine whether the fluid is of a purely thermogenic origin based on the thermal maturity of the fluid and the gas moisture ratio. When executed, the instructions may also cause the processing circuit to generate a modified GOR by correcting the GOR based on at least the first isotope ratio and the gas moisture ratio in response to determining that the fluid is not of a purely thermogenic origin.

[0062] When executed, the instructions may further cause the processing circuit to determine a thermogenic gas replenishment level of the fluid and to correct the GOR or the corrected GOR based on the thermogenic gas replenishment level of the fluid.

[0063] The first alkane may be methane and the second alkane may be ethane. In addition, the thermal maturity includes a vitrinite reflectance equivalent (VRE) value. In addition, when executed, the instructions may further cause the processing circuit to increase or decrease the sampling rate of the fluid based on the thermal maturity of the fluid. In addition, the system may include a drilling system communicatively coupled to the processing circuit. When executed, the instructions may cause the processing circuit to adjust the drilling system based on the thermal maturity of the fluid.

[0064] In another embodiment, the non-transitory computer-readable medium includes an instruction, which, when executed by a processing circuit, causes the processing circuit to receive well logging data about a fluid. The well logging data indicates a plurality of isotope ratios of a plurality of alkanes of the fluid, and the well logging data includes a plurality of quantities. Each corresponding quantity in a plurality of quantities corresponds to a corresponding alkane in a plurality of alkanes. When executed, the instruction also causes the processing circuit to determine the thermal maturity of the fluid based on at least the first isotope ratio in a plurality of isotope ratios of the well logging data corresponding to a first alkane in a plurality of alkanes. In addition, when executed, the instruction causes the processing circuit to determine the gas-oil ratio (GOR) of the fluid based on at least the second isotope ratio in a plurality of isotope ratios corresponding to a second alkane in a plurality of alkanes. When executed, the instruction also causes the processing circuit to determine the gas moisture ratio of the fluid based on at least a portion of a plurality of quantities, determine the fluid type of the fluid based on the gas moisture ratio and the first isotope ratio, and cause the thermal maturity of the fluid, the fluid type of the fluid, and the GOR of the fluid to be displayed.

[0065] The fluid type may include one of pure biogenic methane, a mixture dominated by biogenics, a mixture dominated by thermogenics, dry gas, wet gas, condensate, volatile oil, peak oil, or early oil. In addition, the thermal maturity of the fluid may include a plurality of vitrinite reflectance equivalent (VRE) values. The plurality of VRE values ​​may include a first VRE determined based at least on a first isotopic ratio, a second VRE determined based at least on a second isotopic ratio, and a third VRE determined based at least on a third isotopic ratio of a plurality of isotopic ratios of a third alkane corresponding to the plurality of alkanes.

[0066] When executed, the instructions may cause the processing circuit to determine a biodegradation level of the fluid based on the well log data, determine a thermogenic gas replenishment level of the fluid, and modify the GOR based on the thermogenic gas replenishment level of the fluid. In addition, the instructions may cause the processing circuit to display a first visual indication of a plurality of VRE values, a second visual indication of the biodegradation level, and a third visual indication of the thermogenic gas replenishment level when executed. When executed, the instructions may cause the processing circuit to determine the extent of biodegradation of the fluid based on determining whether a difference between the second VRE and the third VRE exceeds a first threshold, whether a first ratio exceeds a second threshold (where the first ratio is a ratio of a first amount in a plurality of amounts corresponding to a fourth alkane in the plurality of alkanes to a second amount in a plurality of amounts corresponding to a fifth alkane in the plurality of alkanes), whether a second ratio exceeds a third threshold (where the second ratio is a ratio of a third amount in a plurality of amounts corresponding to a sixth alkane in the plurality of alkanes to a fourth amount in a plurality of amounts corresponding to a seventh alkane in the plurality of alkanes), whether a third isotopic ratio is less than a fourth threshold (or, if the value of the third isotopic ratio is greater than the fourth threshold, whether a second difference between the second VRE value and the first VRE value exceeds a fifth threshold), whether the third isotopic ratio exceeds a sixth threshold, whether the third ratio exceeds a seventh threshold (where the third ratio is a ratio of the fourth ratio to the fifth ratio, the fourth ratio is a ratio of the fifth amount in the plurality of amounts corresponding to the second alkane to the sixth amount in the plurality of amounts corresponding to the third alkane, and the fifth ratio is a ratio of the fifth amount to the first amount), or a combination thereof.

[0067] In yet another embodiment, a computer-implemented method includes receiving, via a processing circuit, well logging data about a fluid, wherein the well logging data indicates a plurality of isotope ratios of a plurality of alkanes of the fluid. The computer-implemented method also includes determining, via the processing circuit and based on at least a first isotope ratio in a plurality of isotope ratios of the well logging data corresponding to a first alkane in the plurality of alkanes, a thermal maturity of the fluid. In addition, the computer-implemented method includes determining, via the processing circuit and based on at least a second isotope ratio in a plurality of isotope ratios corresponding to a second alkane in the plurality of alkanes, a gas-oil ratio (GOR) of the fluid. In addition, the computer-implemented method includes displaying, via the processing circuit, the thermal maturity of the fluid and the GOR of the fluid.

[0068] The computer-implemented method may include determining a plurality of vitrinite reflectance equivalent values ​​(VRE) based on a plurality of isotope ratios. The plurality of VRE values ​​include a first VRE determined based on at least a first isotope ratio, a second VRE determined based on at least a second isotope ratio, and a third VRE determined based on at least a third isotope ratio corresponding to a plurality of isotope ratios of a third alkane in the plurality of alkanes. The first alkane may be methane, the second alkane may be ethane, and the third alkane may be propane.

[0069] The computer-implemented method may also include adjusting the drilling system based on the thermal maturity of the fluid via the processing circuitry, increasing or decreasing a sampling rate of the fluid based on the thermal maturity of the fluid via the processing circuitry, or both.

[0070] Thus, the techniques disclosed herein enable analysis and characterization of hydrocarbon-containing fluids, such as mud gas, for example, to log or as part of logging a subterranean formation. Indeed, as described above, well logging data (e.g., advanced mud gas logging data) that includes data on isotopic ratios of hydrocarbons can be used to determine fluid properties (e.g., fluid maturity, gas-to-oil ratio), biodegradation, and recharge. Furthermore, while the examples described above are illustrated with respect to wellbores on land, similar methods can be applied to any acquisition configuration.

[0071] For the purpose of explanation, the foregoing description has been described with reference to specific embodiments. However, the above illustrative discussion is not intended to be exhaustive or to limit the present disclosure to the precise form disclosed. In view of the above teachings, many modifications and variations are possible. In addition, the order in which the elements of the method described herein are illustrated and described can be rearranged, and / or two or more elements can appear at the same time. The embodiments are selected and described in order to best explain the principles of the present disclosure and its practical application, so that other technical personnel in the art can best utilize the present disclosure and various embodiments with various modifications to be suitable for the intended specific use.

[0072] The technology presented and claimed herein is cited and applied to physical and specific examples of practical features that significantly improve the art and are therefore not abstract, intangible, or purely theoretical. In addition, if any claim appended to the end of this specification contains one or more elements that are designated as "means for [performing] [a function] ..." or "steps for [performing] [a function] ...", then those elements should be interpreted under 35 U.S.C. § 112(f). However, for any claim containing an element designated in any other manner, such element should not be interpreted under 35 U.S.C. § 112(f).

Claims

1. A system comprising: Processing circuit; and A non-transitory computer-readable medium comprising instructions that, when executed by a processing circuit, cause the processing circuit to: receiving well log data regarding a fluid, wherein the well log data indicates a plurality of isotope ratios of a plurality of alkanes of the fluid; determining a thermal maturity of the fluid based on at least a first isotope ratio of a plurality of isotope ratios of the well log data corresponding to a first alkane of the plurality of alkanes; determining a gas-oil ratio (GOR) of the fluid based on at least a second isotopic ratio of the plurality of isotopic ratios corresponding to a second alkane of the plurality of alkanes; and Allows display of the thermal maturity of the fluid and the GOR of the fluid.

2. The system of claim 1, wherein: The well log data includes a plurality of quantities, wherein each respective quantity of the plurality of quantities corresponds to a respective alkane in a plurality of alkanes; and The instructions, when executed, further cause the processing circuit to: determining a gas humidity ratio of the fluid based on at least a portion of the plurality of quantities; and The thermal maturity of the fluid is determined based on the gas moisture ratio.

3. The system of claim 2, wherein the instructions, when executed, further cause the processing circuit to: determining the GOR based on at least a second isotope ratio; Determining whether the fluid is of purely thermogenic origin based on the thermal maturity and gas moisture ratio of the fluid; and In response to determining that the fluid is not of purely thermogenic origin, a modified GOR is generated by modifying the GOR based on at least the first isotope ratio and the gas moisture ratio.

4. The system of claim 3, wherein the instructions, when executed, further cause the processing circuit to: determining the extent of thermogenic gas replenishment of the fluid; and The GOR or modified GOR is modified based on the extent of thermogenic gas charge to the fluid.

5. The system of claim 3, wherein: The first alkane includes methane; and The second alkane includes ethane.

6. The system of claim 1, wherein the thermal maturity comprises a vitrinite reflectance equivalent (VRE) value.

7. A non-transitory computer-readable medium comprising instructions which, when executed by a processing circuit, cause the processing circuit to: Receiving well logging data regarding a fluid, wherein the well logging data: multiple isotopic ratios of multiple alkanes of the indicative fluid; and comprising a plurality of amounts, wherein each respective amount in the plurality of amounts corresponds to a respective alkane in the plurality of alkanes; determining a thermal maturity of the fluid based on at least a first isotope ratio of a plurality of isotope ratios of the well log data corresponding to a first alkane of the plurality of alkanes; determining a gas-oil ratio (GOR) of the fluid based on at least a second isotopic ratio of the plurality of isotopic ratios corresponding to a second alkane of the plurality of alkanes; determining a gas humidity ratio of the fluid based on at least a portion of the plurality of quantities; determining a fluid type of the fluid based on the gas humidity ratio and the first isotope ratio; and Allows display of the thermal maturity of the fluid, the fluid type of the fluid, and the GOR of the fluid.

8. The non-transitory computer readable medium of claim 7, wherein the fluid type comprises one of pure biogenic methane, a predominantly biogenic mixture, a predominantly thermogenic mixture, dry gas, wet gas, condensate, volatile oil, peak oil, or early oil.

9. A computer-implemented method comprising: receiving, via processing circuitry, well log data regarding a fluid, wherein the well log data indicates a plurality of isotopic ratios of a plurality of alkanes of the fluid; determining, via the processing circuitry and based on at least a first isotope ratio of a plurality of isotope ratios of the well log data corresponding to a first alkane of the plurality of alkanes, a thermal maturity of the fluid; determining, via the processing circuitry and based on at least a second isotopic ratio of the plurality of isotopic ratios corresponding to a second alkane in the plurality of alkanes, a gas oil ratio (GOR) of the fluid; and The processing circuit displays the thermal maturity of the fluid and the GOR of the fluid.

10. The computer-implemented method of claim 9, comprising determining a plurality of vitrinite reflectance equivalent (VRE) values ​​based on the plurality of isotope ratios, wherein the plurality of VRE values ​​comprises: a first VRE determined based on at least a first isotopic ratio; a second VRE determined based on at least a second isotopic ratio; and A third VRE is determined based on at least a third isotopic ratio of the plurality of isotopic ratios corresponding to a third alkane in the plurality of alkanes.

11. The computer-implemented method of claim 10, wherein: The first alkane includes methane; The second alkane comprises ethane; and The third alkane includes propane.

12. The computer-implemented method of claim 9, comprising: causing, via the processing circuit, a drilling system to be adjusted based on the thermal maturity of the fluid; increasing or decreasing, via the processing circuit, a sampling rate of the fluid based on a thermal maturity of the fluid; or both.

Images