Method and system for pre-judging formation water outlet condition of oil and gas reservoir

Abstract

The invention provides an oil and gas reservoir formation water outlet condition pre-discrimination method and system, and the method comprises the steps: carrying out the multi-scale recognition of the formation water development degree of a corresponding to-be-analyzed block through integrating logging data and logging data, and determining a formation water development risk horizon; performing mineralization degree analysis on formation return liquid during drilling and logging, and determining a formation water development layer according to a formation water mineralization degree index; according to the fracture structure geological characteristics of the formation water development horizon, the scale attributes of the formation water are analyzed, and the scale attributes comprise constant-volume sealing water and bottom water; based on the formation water development risk horizon, the formation water development horizon and the formation water scale attribute, an acid fracturing construction scheme and development operation parameters are decided through information. By adopting the scheme, the problems of many secondary problems and insufficient reliability in the prior art can be solved, the formation water outlet condition can be predicted before well completion, the well completion scheme of a complex oil and gas well can be optimized, the working system of oil testing and production testing can be guided, the risk of water layer pressure opening can be effectively controlled, and the probability of destructive production can be reduced.

Description

Technical Field

[0001] This invention relates to the field of formation water prediction technology for oil and gas reservoirs, and in particular to a method and system for predicting formation water production in oil and gas reservoirs. Background Technology

[0002] To determine whether formation water is present in fractured-vuggy carbonate oil and gas reservoirs during drilling, the usual method is to assess the fluid production observed after well testing. However, this method typically involves acid fracturing of the aquifer after formation water is confirmed. Acid fracturing involves injecting acid into the aquifer to chemically react with the formation rocks, thereby increasing permeability. Without a confirmed formation water presence, acid fracturing carries the risk of breaking up the aquifer. Furthermore, during well testing, operating at high efficiency can lead to bottom and edge water coning, blocking oil and gas pathways and potentially causing irreversible and destructive production in some wells. This can result in reduced production capacity, decreased recovery rate, or even permanent damage, rendering the well unusable. In conclusion, existing methods for determining formation water presence suffer from numerous secondary problems and lack reliability and practicality.

[0003] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method and system for pre-judging formation water production in oil and gas reservoirs. This method overcomes the numerous secondary problems and insufficient reliability of existing technologies, enabling the prediction of formation water production before well completion. It optimizes completion schemes for complex oil and gas wells, guides testing and production procedures, effectively controls the risk of water layer detonation, and reduces the probability of destructive exploitation. During implementation, the method integrates logging data and well logging data at multiple scales to identify the formation water development level of the corresponding block to be analyzed, determining the formation water development layer. It analyzes the salinity of the formation fluid returned during drilling and logging, determining the formation water type of the formation water development layer based on the formation water salinity index. Furthermore, it analyzes the scale attributes of the formation water in oil and gas wells based on the fault geological characteristics of the formation water development layer. Finally, it determines the acid fracturing construction scheme and development operation parameters based on the formation water layer, formation water type, and formation water scale attribute information. Preferably, in one embodiment, the method includes:

[0005] Step S10: Integrate well logging data and well logging data to identify the formation water development level of the corresponding block to be analyzed at multiple scales, and determine the formation water development risk layers;

[0006] Step S20: Analyze the mineralization of the formation fluid returned during drilling and logging at each formation water development risk stratum. Based on the formation water mineralization index, determine whether formation water is present. If formation water is present, the formation water development risk stratum can be identified as a formation water development stratum.

[0007] Step S30: Analyze the scale attributes of formation water in oil and gas wells based on the geological characteristics of the fracture structure of the formation water development strata.

[0008] Step S40: Decision on acid fracturing construction plan and development operation parameters based on formation water development risk strata, formation water development strata and formation water property information.

[0009] Optionally, in one embodiment, the process of determining the formation water development risk layer in step S10 includes: step S11: based on the seismic data, logging data, and return fluid salinity characteristics of the block to be analyzed, identify the formation water development risk layer corresponding to the block to be analyzed.

[0010] Furthermore, in one embodiment, step S11, the process of identifying the formation water development risk layers corresponding to the block to be analyzed, includes:

[0011] Based on the rock type, porosity, permeability, and pressure data from well logging, the reservoir development level of the stratigraphic units that meets the set conditions is identified.

[0012] Then, based on the logging data, the layers with oil and gas indications were identified and excluded, and the remaining blocks were identified as layers with formation water development risk.

[0013] In a preferred embodiment, the stratigraphic horizons whose reservoir development meets the set conditions include those possessing one or more of the following seismic facies characteristics:

[0014] a1. Seismic phases whose external features are of the fracture type and whose seismic reflection amplitude features exhibit beaded signal characteristics;

[0015] a2. Seismic phases whose external features are of the fault type and whose seismic reflection amplitude characteristics exhibit chaotic signal characteristics;

[0016] a3. Seismic phases exhibiting linear weak reflection signal characteristics in terms of seismic reflection amplitude.

[0017] Furthermore, in one embodiment, step S10, the process of determining the formation water development horizon, further includes:

[0018] Step S12: Establish a logging-formation water level relationship chart based on the logging resistivity and the actual drilled water-producing layers, which is used to further predict the formation water development layers in the block to be analyzed.

[0019] Optionally, in one embodiment, in step S12, the formation water development level of the block to be analyzed is further predicted as follows:

[0020] Step S121: Determine the stratigraphic horizons outside the identified stratigraphic water development risk horizons in the block to be analyzed as undetermined horizons;

[0021] Step S122: Based on the undetermined strata, draw the logging parameters-formation water chart of the current undetermined strata and compare it with the pre-established standard logging parameters-formation water experience chart to determine whether the chart position corresponding to the resistivity of the logging curve of the undetermined strata is in the water risk zone. If so, and there is no oil and gas display in the logging, it is determined that the current undetermined strata also belongs to the formation water development risk strata.

[0022] In one embodiment, in step S20, the formation water salinity index includes: formation water type, total mineral ion concentration, bromide ion concentration, and iodide ion concentration; the formation water type includes Na2SO4 water type, NaHCO3 water type, MgCl2 water type, and CaCl2 water type.

[0023] In an optional embodiment, step S30 includes the following operations.

[0024] Step S31: Establish heterogeneous geological models and fault models for ultra-deep fault-controlled fracture-vuggy reservoirs;

[0025] Step S32: Based on the information from the geological model and the fault model, determine the formation water scale attributes according to the relationship between the water-producing strata and the reservoir and fault zones; the formation water scale attributes include water sealed in the branch fault zones and large bottom water in the main fault zones.

[0026] Based on other aspects of the methods described in any one or more of the above embodiments, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more of the above embodiments.

[0027] Based on the application aspects of the methods described in any one or more of the above embodiments, the present invention also provides a pre-judgment system for formation water outflow, which executes the methods described in any one or more of the above embodiments.

[0028] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0029] This invention provides a method and system for pre-judging formation water production. Based on well logging data, it identifies the formation water development level of the corresponding analysis block; establishes a well logging-formation water level relationship map based on well logging resistivity and actual drilled water-producing layers to predict the formation water development layers in the analysis block; collects drilling fluid and uses physical property analysis technology to identify the fluid and locate the formation water production situation; analyzes the bottom water production scale attribute of the oil well based on the fracture structure characteristics of the oil well, combined with drilling data and seismic profile data; determines the acid fracturing avoidance area based on this, and decides the oil testing and production operation plan based on the bottom water production scale attribute; pre-judging the formation water production situation before well completion optimizes the completion plan for complex oil and gas wells, guides the oil testing and production operation system, effectively controls the risk of water layer detonation, and reduces the probability of destructive exploitation.

[0030] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0031] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0032] Figure 1 A flowchart illustrating a method for pre-determining formation water outflow conditions according to an embodiment of the present invention;

[0033] Figure 2 An example of a seismic facies diagram of a favorable reservoir in fracture-vuggy carbonate rocks, provided by an embodiment of the present invention for the method of pre-judging formation water outflow;

[0034] Figure 3 An example of establishing an empirical chart showing the relationship between formation water production and logging resistivity, total porosity, and formation water in the method for pre-judging formation water production in the embodiment of the present invention;

[0035] Figure 4 Example of a geological model diagram of small-scale water storage in branch fault zones and large-scale bottom water in main faults in the pre-judgment method of formation water outflow provided in the embodiments of the present invention;

[0036] Figure 5 A schematic diagram of a pre-judgment system for determining formation water outflow conditions, provided in another embodiment of the present invention. Detailed Implementation

[0037] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples. Those skilled in the art will then fully understand how the present invention uses technical means to solve technical problems and achieve technical effects, and will be able to implement the present invention specifically based on the above-described implementation process. It should be noted that, as long as there is no conflict, the various embodiments and features of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0038] Although the flowchart describes the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. A process can terminate when its operation is complete, but it may also have additional steps not included in the diagram. A process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0039] Computer equipment includes user equipment and network equipment. User equipment or clients include, but are not limited to, computers, smartphones, and PDAs (Personal Digital Assistants); network equipment includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud based on cloud computing consisting of a large number of computers or network servers. Computer equipment can operate independently to implement this invention, or it can connect to a network and implement this invention through interaction with other computer devices within the network. The network in which the computer equipment resides includes, but is not limited to, the Internet, wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), and VPN networks.

[0040] The terms “first,” “second,” etc., may be used herein to describe various units, but these units should not be limited by these terms; they are used merely to distinguish one unit from another. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. When a unit is referred to as “connected” or “coupled” to another unit, it may be directly connected or coupled to said other unit, or there may be intermediate units present.

[0041] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0042] To determine whether formation water is present during drilling, the flow rate after well testing is typically used. However, this method usually only confirms formation water presence after acid fracturing of the aquifer. Acid fracturing involves injecting acid into the aquifer, causing a chemical reaction between the acid and the formation rock to increase permeability. Acid fracturing is commonly used to address declining oil well production by improving the permeability of the surrounding rock, thereby increasing oil recovery. In practice, a suitable acid formulation is selected, the acid is injected into the wellbore, and after reacting with the formation rock for a certain period, the reaction products are expelled under pressure. Acid fracturing technology has significant applications in oil exploration and development, improving oilfield productivity and recovery. However, acid fracturing carries the risk of breaking up the aquifer. Furthermore, during well testing, operating at high efficiency can lead to bottom and edge water coning, blocking oil and gas pathways and potentially causing irreversible and destructive exploitation of some wells.

[0043] Generally, destructive exploitation of oil and gas wells refers to a reduction in production capacity, decreased recovery rate, or even permanent damage during the production process due to a series of factors (such as high operating conditions and groundwater influence), rendering the well unable to continue producing oil and gas. Specifically, using high operating conditions during well testing means employing high-efficiency production operations during oil exploration and development to rapidly extract oil and gas resources by increasing production. Water coning at the bottom and edge of the well refers to the entry of groundwater from the bottom of the well into the oil or gas well during production, forming a water cone. Water coning occurs due to high production rates and groundwater pressure, causing groundwater to seep into the well. When water coning enters the well, it mixes with oil and gas, blocking the oil and gas pathway and reducing production and recovery rates. Irreversible destructive exploitation of some oil and gas wells means that due to water coning at the bottom and edge of the well, some wells have suffered irreversible damage during production. This can lead to a significant decrease in the well's profitability, or even prevent it from returning to its original production level. In summary, existing methods for determining whether formation water is present during drilling have many secondary problems, resulting in insufficient reliability and practicality.

[0044] To address the aforementioned problems, this invention provides a method for pre-judging formation water production, which can effectively predict whether formation water will emerge before well completion. This optimizes well completion methods for oil and gas wells with complex oil-water relationships, guides testing and production procedures, and helps formulate reasonable testing and production plans, preventing destructive exploitation that could lead to oil and gas well reserve losses.

[0045] The following describes the detailed flow of the method according to an embodiment of the present invention with reference to the accompanying drawings, the steps of which can be executed in a computer system containing, for example, a set of computer-executable instructions. Although the logical order of the steps is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0046] Example 1

[0047] Well logging data refers to the information on solid, liquid, and gaseous materials returned from the wellbore during the drilling process, obtained, collected, recorded, and analyzed using methods such as rock and mineral analysis, geochemistry, and geophysics. This data is used to establish well logging geological profiles, discover oil and gas shows, and evaluate oil and gas reservoirs. In addition, it can record drilling time, loss of control fluid, venting, overflow, or loss of return, thereby predicting reservoir development and playing an important guiding role in determining well completion and production plans.

[0048] Figure 1 This diagram illustrates a flowchart of the method for pre-determining formation water outflow conditions provided in Embodiment 1 of the present invention. (Refer to...) Figure 1 As can be seen, the method includes the following steps.

[0049] Step S10: Based on well logging data and well logging data, identify the formation water development level of the corresponding block to be analyzed at multiple scales, and determine the formation water development risk layers;

[0050] Step S20: Analyze the mineralization of the formation fluid returned during drilling and logging of each formation water development risk zone. Based on the formation water mineralization index, determine whether formation water is present. If formation water is present, the formation water development risk zone mentioned in step S10 can be identified as a formation water development zone.

[0051] Step S30: Analyze the scale attributes of formation water in oil and gas wells based on the geological characteristics of the fracture structure of the formation water development strata.

[0052] Step S40: Decision on acid fracturing construction scheme and development operation parameters based on formation water development risk strata, formation water development strata and formation water scale attribute information.

[0053] The scheme described in the above embodiments enables reliable pre-determination of formation water production, effectively predicting whether formation water will emerge before well completion, optimizing well completion methods for oil and gas wells with complex oil-water relationships, guiding the testing and production work system, and formulating reasonable testing and production plans. In carbonate fractured-vuggy reservoirs, formation water development zones generally have good reservoir development, but logging shows no oil or gas shows. Based on drilling time, loss of circulation and control fluid status, venting, and overflow or loss of return, a preliminary assessment of reservoir development can be made. Combined with oil and gas shows, potential formation water development zones can be preliminarily inferred, serving as risk zones for formation water development.

[0054] In a preferred embodiment, step S10 is first performed: based on well logging data and well logging data, the formation water development level of the corresponding block to be analyzed is identified at multiple scales, and the formation water development risk layer is determined.

[0055] In an optional embodiment, step S10 includes: step S11: based on the seismic data, logging data, and salinity characteristics of the returned fluid of the block to be analyzed, identify the formation water development risk layers of the corresponding block to be analyzed.

[0056] In practical applications, based on the seismic response characteristics, well logging oil and gas display characteristics, and returned fluid salinity characteristics of the block to be analyzed, the formation water development level of the corresponding block to be analyzed is identified; formations that meet the set conditions for reservoir development but have no oil and gas display are identified as formation water development risk layers.

[0057] The formations whose reservoir development meets the set conditions include those whose reservoir seismic facies meet the set conditions; therefore, if a formation in the block to be analyzed is a favorable reservoir seismic facies, but there is no oil and gas indication in the well logging, it can be identified as a formation with well-developed formation water.

[0058] In an optional embodiment for practical application, step S11 includes the following operations:

[0059] Based on the rock type, porosity, permeability, and pressure data from well logging, the reservoir development level of the stratigraphic units that meets the set conditions is identified.

[0060] This leads to the exclusion of layers with oil and gas indications based on logging data, with the remaining blocks identified as layers at risk of formation water development.

[0061] In step S11, favorable reservoir seismic facies include horizons possessing one or more of the following seismic facies characteristics: a1. Seismic facies with fracture-type morphology and beaded signal characteristics in seismic reflection amplitude; a2. Seismic facies with fracture-type morphology and disordered signal characteristics in seismic reflection amplitude; a3. Seismic facies with linear weak reflection signal characteristics. If any of the above multiple reservoir seismic facies conditions are met, and no oil or gas shows are also present, then the horizon can be identified as a high-risk horizon for formation water development, such as... Figure 2 As shown.

[0062] Considering the heterogeneity and variability of formation water development strata, the accuracy and comprehensiveness of identifying formation water development strata using the above methods are limited, and there may be cases where strata belonging to formation water development risk strata are missed. Therefore, the embodiments of the present invention combine well logging data to further comprehensively identify formation water development risk strata.

[0063] Based on this, the design step S10 of the embodiment of the present invention further includes:

[0064] Step S12: Establish a logging-formation water level relationship chart based on the logging resistivity and the actual drilled water-producing layers, which will be used to further predict the formation water development layers in the block to be analyzed;

[0065] In a preferred embodiment, the formation water development risk strata in the block to be analyzed are further predicted by the following steps:

[0066] Step S121: Determine the stratigraphic horizons in the block to be analyzed that are not identified as stratigraphic horizons with well-developed formation water as undetermined horizons;

[0067] Step S122: Based on the undetermined stratum, draw the logging parameters-formation water chart of the current undetermined stratum and compare it with the pre-established standard logging parameters-formation water experience chart to determine whether the chart position corresponding to the resistivity of the logging curve of the undetermined stratum is in the water risk range. If so, and there is no oil and gas display in the logging, determine that the current undetermined stratum is a formation water development risk stratum.

[0068] This invention establishes a well logging-formation water level relationship chart based on well logging resistivity and actual drilling water-producing layers to predict formation water development risk layers in the block to be analyzed; step S122, the process of determining formation water development risk layers based on the relationship between well logging resistivity, total porosity and formation water includes:

[0069] Based on the relationship between historical oilfield drilling logging resistivity, total porosity, and formation water, a standard logging parameter-formation water empirical chart is established. A comparative analysis is then performed between the current undetermined formation's logging parameter-formation water chart and the standard logging parameter-formation water empirical chart. During application, the chart position corresponding to the resistivity of the undetermined formation's logging curve is used to determine whether it falls within a water-bearing risk zone, thus identifying whether the formation corresponding to the resistivity segment is a formation with a high risk of formation water development. Figure 3 As shown.

[0070] Specifically, in an optional embodiment, step S12, the process of establishing a standard logging parameter-formation water empirical chart based on logging resistivity and actual drilled water-producing layers, includes:

[0071] Historically drilled water-producing wells were selected as sample wells;

[0072] Based on the logging data of the sample wells, logging resistivity and total porosity data are obtained. Combined with the analysis of the actual water-producing layers of the sample wells, logging-formation water layer relationship charts for different types of reservoirs are formed.

[0073] The above embodiments of the present invention determine possible water-producing layers based on well logging data, establish a relationship chart between well logging resistivity and water-producing layers based on actual drilled water-producing wells, and determine whether formation water is likely to be produced based on the relationship chart, as well as predict water-producing risk layers.

[0074] Well logging resistivity refers to the resistivity of formation rocks measured using well logging instruments in oil exploration. Formation rock resistivity is the degree of resistance of a unit volume of rock to electric current, usually expressed in ohms (Ω·m).

[0075] Well logging resistivity can assess the physical characteristics of formation rocks, such as water content, porosity, and permeability, thereby helping geologists and engineers understand the formation conditions of the wellbore and guiding oil and gas exploration and development. If the resistivity meets the conditions for water-bearing areas on the chart, the reservoir properties are good, and there are no oil and gas shows in the well logging, then it is identified as a formation water-prone area.

[0076] In practical applications, technicians can flexibly choose between well logging data or well logging information to determine the identification logic and sequence of formation water development risk zones based on the data foundation and requirements.

[0077] Further, step S20 is performed to analyze the mineralization of the formation fluid returned during drilling and logging of the formation water-developed strata. Based on the formation water mineralization index and marker minerals, the formation water type of the formation water-developed strata is determined.

[0078] In step S20, the formation water salinity index (formation water marker mineral index) includes: total mineral ion concentration, bromide ion concentration and iodide ion concentration.

[0079] In practical applications, the Sulin classification method can be used to distinguish different types of formation water. That is, based on different ion mineralization, formation water is divided into four types: Na2SO4, NaHCO3, MgCl2, and CaCl2. Therefore, formation water types include Na2SO4 water type, NaHCO3 water type, MgCl2 water type, and CaCl2 water type.

[0080] Considering that different formation water types have corresponding mineral ion data, this embodiment of the invention sets corresponding mineral ion index identification rules for each formation water type. When the concentration of mineral ions in the returned fluid meets the mineral ion index identification rules for a certain water type, the current returned fluid is determined to be formation water, and its formation water type is determined. This embodiment of the invention mainly identifies CaCl2 water type returned fluids. For example, the marine carbonate formation water in the Tarim Basin is mainly CaCl2 water type, containing bromide ions and iodide ions. The mineralization varies in different areas, ranging from 50,000 to 250,000. Based on this, for the formation water development strata in this area, the mineralization of the returned fluid can be used to determine whether it is formation water and to identify the formation water type. The mineralization of adjacent wells is mainly referenced. The total mineral ion concentration, bromide ion concentration, and iodide ion concentration in the returned fluid are analyzed. If the bromide and iodide ion contents in the returned fluid meet the above conditions, it is determined that the returned fluid belongs to formation water, and the current formation water can be identified as CaCl2 water type. If the distribution range of bromide and iodide ions is too small, it may be condensate water or fresh water injection water. If the distribution range of bromide and iodide ions is too large, it may be mixed water affected by factors such as storage modification acid solution.

[0081] Further, step S30 is performed to analyze the scale attributes of formation water in oil and gas wells based on the geological characteristics of the fracture structure of the formation water development strata.

[0082] The specific method in step S30 is as follows:

[0083] S31. Establish heterogeneous geological models and fracture models for ultra-deep fault-controlled fracture-vuggy reservoirs;

[0084] S32. Determine the formation water scale attributes based on the relationship between the water-producing layer and the reservoir and fault zone.

[0085] In an optional embodiment, in step S32, the formation water scale attributes include small-scale sealed water in branch fault zones and large-scale bottom water in main fault zones.

[0086] This invention analyzes the scale of bottom water production in oil wells based on the fracture structure characteristics of the well at the formation water outlet location, combined with drilling data and seismic profile data. In practical applications, a detailed analysis of the fracture structure is first performed to determine whether the well is producing bottom water from a main fracture or sealed water from a branch fracture. Then, based on the fracture structure characteristics of the oil well, combined with actual well runoff and leakage, oil and gas shows, logging characteristics, and seismic profiles, a detailed analysis of the surrounding fractures is conducted to determine whether the well is producing bottom water from a main fracture or sealed water from a branch fracture. Figure 4 As shown.

[0087] Based on the above identification results, step S40 is executed to determine the acid fracturing construction plan and development operation parameters according to the formation water development risk strata, formation water development strata and formation water attribute information.

[0088] The decision-making process identifies acid fracturing avoidance zones based on formation water development risk levels and related locations. This controls the risk of water layer delamination and, combined with bottom water production data, provides comprehensive data support for oil testing and production operation plans, reducing the probability of destructive exploitation. In practical applications, personnel can choose to base their acid fracturing avoidance decisions on either formation water development risk levels or formation water development levels, depending on actual construction needs.

[0089] Based on the above steps, this invention can determine the formation water production situation, the possible location of formation water production, rationally select the well completion acid fracturing scheme, avoid acid fracturing water layers, and formulate a reasonable oil testing and production system to guide the later development of oil and gas wells.

[0090] In practical applications, the identification results of the formation water scale attributes of the formation water development layer can provide guidance for the design of well completion acid fracturing schemes. For example, considering that formation water is usually at the bottom of the producing section, in the operation of cement plugging before acid fracturing, the plug surface can be designed to be higher than the formation water development section, that is, higher than the oil-gas-water interface, to acid fracturing the oil and gas layer.

[0091] In addition, based on the formation water scale attributes, whether it is sealed water from branch fractures or bottom water from main fractures, the water development level of the corresponding area can be adaptively determined to guide the well depth design of deployment wells; specifically, if sealed water is from branch fractures, the well depth of later deployment wells can be unrestricted, while if bottom water is from main fractures, the well depth of later deployment wells must be higher than the oil-water interface.

[0092] Regarding the oil testing and production operation system, for identified formation water-developed strata, a small-amplitude operation system and low production rate are designed for production to prevent formation water from coning and blocking oil and gas channels due to excessively high production rates, which would cause destructive production.

[0093] The solution of this invention can predict whether formation water will be produced during drilling before well completion, optimize the completion method of oil and gas wells with complex oil-water relationships, guide the work system of oil testing and production testing, formulate reasonable production testing plans, and reduce the risk of destructive mining.

[0094] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0095] It should be noted that, in other embodiments of the present invention, the method can also combine one or more of the above embodiments to obtain a new method for pre-judging formation water conditions, so as to reliably predict whether there is formation water in the formation and the location of formation water.

[0096] It should be noted that, based on the methods in any one or more embodiments of the present invention described above, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more embodiments. When the program code is executed by the operating system, it can implement the pre-determination method for formation water outflow as described above.

[0097] Example 2:

[0098] The methods described in detail in the above-disclosed embodiments of the present invention can be implemented using various forms of devices or systems. Therefore, based on other aspects of the methods described in any one or more of the above embodiments, the present invention also provides a pre-judgment system for determining formation water outflow, which is used to execute the pre-judgment method for determining formation water outflow described in any one or more of the above embodiments. Specific embodiments are given below for detailed description.

[0099] Specifically, Figure 5 The diagram shows a schematic representation of the pre-determination system for formation water outflow provided in an embodiment of the present invention. Figure 5 As shown, the system includes:

[0100] The formation water risk layer identification module is configured to identify the formation water development level of the corresponding block to be analyzed at multiple scales by integrating well logging data and well logging data, and determine the formation water development risk layer.

[0101] The formation water level determination module is configured to perform mineralization analysis on the formation fluid returned during drilling and logging of each formation water development risk level. Based on the formation water mineralization index, it determines whether formation water is present. If formation water is present, the identified formation water development risk level can be determined as a formation water development level.

[0102] The formation water property analysis module is configured to analyze the scale properties of formation water in oil and gas wells based on the geological characteristics of the fracture structures in the formation water development strata.

[0103] The operation decision guidance module is configured to determine the acid fracturing construction plan and development operation parameters based on the formation water development risk strata, formation water development strata, and formation water scale attribute information.

[0104] Optionally, in one embodiment, the formation water risk layer identification module includes:

[0105] The well logging data identification unit is configured to determine the formation water development risk layers through the following logic: based on the seismic data, well logging data, and return fluid salinity characteristics of the block to be analyzed, identify the formation water development risk layers corresponding to the block to be analyzed.

[0106] Furthermore, in one embodiment, the logging data identification unit identifies the formation water development risk layers corresponding to the block to be analyzed by the following operation:

[0107] Based on the rock type, porosity, permeability, and pressure data from well logging, the reservoir development level of the stratigraphic units that meets the set conditions is identified.

[0108] Then, based on the logging data, the layers with oil and gas indications were identified and excluded, and the remaining blocks were identified as layers with formation water development risk.

[0109] In a preferred embodiment, the stratigraphic horizons whose reservoir development meets the set conditions include those possessing one or more of the following seismic facies characteristics:

[0110] a1. Seismic phases with fracture-like external features and seismic reflection amplitude characteristics exhibiting beaded signal characteristics; a2. Seismic phases with fracture-like external features and seismic reflection amplitude characteristics exhibiting chaotic signal characteristics;

[0111] a3. Seismic phases exhibiting linear weak reflection signal characteristics in terms of seismic reflection amplitude.

[0112] Furthermore, in one embodiment, the formation water risk layer identification module further includes:

[0113] The well logging data identification unit is configured to: establish a well logging-formation water level relationship chart based on well logging resistivity and actual drilled water-producing layers, which is used to further predict the formation water development level of the block to be analyzed.

[0114] Optionally, in one embodiment, the well logging data identification unit further predicts the formation water development levels of the block to be analyzed by operating as follows:

[0115] Stratigraphic horizons other than those identified as having a risk of formation water development in the block to be analyzed are designated as undetermined horizons.

[0116] Based on the undetermined strata, a comparison and analysis are performed between the logging parameters-formation water chart of the current undetermined strata and the pre-established standard logging parameters-formation water experience chart. It is determined whether the chart position corresponding to the resistivity of the logging curve of the undetermined strata is in the water risk zone. If so, and there is no oil and gas indication in the logging, it is determined that the current undetermined strata also belongs to the formation water development risk strata.

[0117] In one embodiment, the formation water level determination module sets formation water salinity indicators including: formation water type, total mineral ion concentration, bromide ion concentration, and iodide ion concentration; formation water type includes Na2SO4 water type, NaHCO3 water type, MgCl2 water type, and CaCl2 water type.

[0118] In an optional embodiment, the formation water property analysis module is configured to perform the following operations:

[0119] Establish heterogeneous geological models and fault models for ultra-deep fault-controlled fracture-vuggy reservoirs;

[0120] Based on information from geological and fault models, the formation water scale attributes are determined according to the relationship between the water-producing strata and the reservoir and fault zones; the formation water scale attributes include water sealed in branch fault zones and large bottom water in main fault zones.

[0121] In the pre-judgment system for formation water outflow provided in this embodiment of the invention, each module or unit structure can operate independently or in combination according to actual parameter preparation and relational diagram application requirements to achieve the corresponding technical effects.

[0122] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0123] The phrase "an embodiment" in the specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0124] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for pre-determining formation water production in oil and gas reservoirs, characterized in that, The method includes: Step S10: Based on well logging data and well logging data, identify the formation water development level of the corresponding block to be analyzed at multiple scales, and determine the formation water development risk layers; Step S20: Analyze the mineralization of the formation fluid returned during drilling and logging at each formation water development risk stratum. Based on the formation water mineralization index, determine whether formation water is present. If formation water is present, the formation water development risk stratum can be identified as a formation water development stratum. Step S30: Analyze the scale attributes of formation water in oil and gas wells based on the geological characteristics of the fracture structure of the formation water development strata. Step S40: Decision on acid fracturing construction scheme and development operation parameters based on formation water development risk strata, formation water development strata and formation water scale attribute information.

2. The method according to claim 1, characterized in that, In step S10, the process of determining the formation water development risk level includes: Step S11: Based on the seismic data, logging data, and return fluid salinity characteristics of the block to be analyzed, identify the formation water development risk level of the corresponding block to be analyzed.

3. The method according to claim 2, characterized in that, Step S11, the process of identifying the formation water development risk layers corresponding to the block to be analyzed, includes: Based on the rock type, porosity, permeability, and pressure data from well logging, the reservoir development level of the stratigraphic units that meets the set conditions is identified. Then, based on the logging data, the layers with oil and gas indications were identified and excluded, and the remaining blocks were identified as layers with formation water development risk.

4. The method according to claim 1, characterized in that, Strata whose reservoir development meets the set conditions include those with one or more of the following seismic facies characteristics: a1. Seismic phases whose external features are of the fracture type and whose seismic reflection amplitude features exhibit beaded signal characteristics; a2. Seismic phases whose external features are of the fault type and whose seismic reflection amplitude characteristics exhibit chaotic signal characteristics; a3. Seismic phases exhibiting linear weak reflection signal characteristics in terms of seismic reflection amplitude.

5. The method according to claim 1, characterized in that, In step S10, the process of determining the stratigraphic water development horizon also includes: Step S12: Establish a logging-formation water level relationship chart based on the logging resistivity and the actual drilled water-producing layers, which is used to further predict the formation water development layers in the block to be analyzed.

6. The method according to claim 5, characterized in that, In step S12, the formation water development horizons of the block to be analyzed are further predicted according to the following operations: Step S121: Determine the stratigraphic horizons outside the identified stratigraphic water development risk horizons in the block to be analyzed as undetermined horizons; Step S122: Based on the undetermined stratum, draw the logging parameters-formation water chart of the current undetermined stratum and compare it with the pre-established standard logging parameters-formation water experience chart to determine whether the chart position corresponding to the resistivity of the logging curve of the undetermined stratum is in the water risk range. If so, and there is no oil and gas display in the logging, it is determined that the current undetermined stratum also belongs to the formation water development risk stratum.

7. The method according to claim 1, characterized in that, In step S20, the formation water salinity indicators include: formation water type, total mineral ion concentration, bromide ion concentration, and iodide ion concentration; formation water type includes Na2SO4 water type, NaHCO3 water type, MgCl2 water type, and CaCl2 water type.

8. The method according to claim 1, characterized in that, Step S30 includes the following operations Step S31: Establish heterogeneous geological models and fault models for ultra-deep fault-controlled fracture-vuggy reservoirs; Step S32: Based on the information from the geological model and the fault model, determine the formation water scale attributes according to the relationship between the water-producing strata and the reservoir and fault zones; the formation water scale attributes include water sealed in the branch fault zones and large bottom water in the main fault zones.

9. A storage medium, characterized in that, The storage medium stores program code that can implement the method as described in any one of claims 1 to 8.

10. A system for pre-determining formation water outflow, characterized in that, The system performs the method as described in any one of claims 1 to 8.

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