A method and system for quantitatively evaluating overflow formation energy

Abstract

The application discloses a method and system for quantitatively evaluating overflow formation energy, comprising the following steps: calculating real-time flow data of an annular space according to real-time data of total pool volume change before and after overflow shut-in; calculating real-time proportion characteristic data of an invading fluid occupying the annular space according to the real-time annular flow data, in combination with a drilling tool assembly and a well structure; acquiring real-time data of standpipe pressure and casing pressure before and after the overflow shut-in, and calculating invading fluid density in combination with the real-time proportion characteristic data; calculating average formation energy of an overflow process according to real-time standpipe pressure data and the invading fluid density; and grading the formation energy in the overflow process according to the average formation energy. The application can quickly and effectively quantitatively calculate the formation energy, and provide corresponding basis for adaptive selection of well killing modes.

Description

Technical Field

[0001] This invention relates to the field of safe drilling technology, and in particular to a method and system for quantitatively evaluating the energy of overflow formations in deep and ultra-deep well drilling. Background Technology

[0002] With the increasing demand for oil and gas resources from my country's economy and society, oil and gas exploration and development are gradually moving towards deep and complex reservoirs, such as the Sichuan Basin and the Tarim Basin, which contain abundant oil and gas resources in their deep strata. Due to the extremely deep burial of resources, extremely high bottom-hole pressure and temperature, and complex geological conditions in these areas, a series of drilling challenges have arisen, especially well control safety issues.

[0003] For deep-buried marine carbonate reservoirs, the reservoir space is mainly composed of pores and fractures, making them prone to gas-liquid displacement, prolonged circulation and degassing times, and overflows during drilling. Due to a lack of understanding of formation energy, it is difficult to quickly and accurately select a suitable well control method after an overflow occurs, leading to overflow well control failures, prolonged non-drilling time, and increased drilling costs.

[0004] Current technologies primarily focus on calculating and analyzing formation pressure in overflow formations, lacking a quantitative evaluation scheme for overflow formation energy. Therefore, existing technologies need to provide a quantitative evaluation scheme for overflow formations based on the variation characteristics of engineering feature parameters. This scheme would enable quantitative classification of formation energy, thereby providing technical guidance for overflow well control. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for quantitatively evaluating formation energy during a blowout, comprising: calculating real-time annular flow rate data based on real-time data of total pool volume changes before and after blowout shut-in; calculating real-time percentage characteristics of the annular space occupied by invading fluid based on the real-time annular flow rate data, combined with the drill string assembly and wellbore structure; acquiring real-time data of standpipe pressure and casing pressure before and after blowout shut-in, and calculating the invading fluid density based on the real-time percentage characteristics data; calculating the average formation energy during the blowout process based on the real-time standpipe pressure data and the invading fluid density; and evaluating the formation energy level during the blowout process based on the average formation energy.

[0006] Preferably, before the step of calculating the real-time flow data of the annulus based on the real-time data of the total pool volume change before and after the overflow well shut-in, the method includes: determining a specified time period from a first moment before the overflow well shut-in to the shut-in moment; acquiring real-time dynamic data of vertical pressure, casing pressure, suspended weight, outlet flow rate and total pool flow rate within the specified time period, and identifying the change time corresponding to each dynamic data; and determining the actual start time of the overflow based on the change time of each parameter.

[0007] Preferably, the step of calculating the real-time flow rate data of the annulus based on the real-time data of the total pool volume change before and after the overflow well shut-in includes: calculating the real-time overflow velocity of the intruding fluid during the overflow process formed from the actual start time of the overflow to the well shut-in time; and obtaining the real-time flow rate data of the annulus based on the real-time overflow velocity of the intruding fluid and the real-time dynamic data of the inlet flow rate during the overflow process.

[0008] Preferably, the step of calculating the real-time percentage characteristic data of the invading fluid occupying the annular space based on real-time annular flow data, combined with the drill string assembly and wellbore structure, includes: calculating the real-time volume data of the mixed fluid in the annulus during the overflow process based on the real-time annular flow data; obtaining an annular size distribution characteristic structure array based on the drill string assembly and the wellbore structure; and calculating the volume fraction of the mixed fluid occupying the annular space and the vertical length it occupies at each gas intrusion overflow moment based on the real-time volume data of the mixed fluid, the annular size distribution characteristic structure array, and well inclination data, thereby obtaining the real-time percentage characteristic data.

[0009] Preferably, the process of calculating the intrusion fluid density includes: determining the drilling fluid density change characteristics during the overflow process based on the original drilling fluid density and drilling fluid rheological characteristics, combined with real-time standpressure data and real-time casing pressure data during the overflow process; and obtaining the intrusion fluid density from the standpressure data and casing pressure data corresponding to the shut-in time based on the real-time standpressure data, the real-time casing pressure data, the drilling fluid density change characteristics, and the real-time percentage characteristic data.

[0010] Preferably, the step of calculating the average formation energy of the overflow process based on real-time standpressure data and the density of the invading fluid includes: calculating the derivative of the standpressure data corresponding to each gas invading overflow time interval based on the real-time standpressure data during the overflow process; determining the overflow formation pressure coefficient based on the standpressure data, casing pressure data, and drilling fluid density data at the shut-in time; and calculating real-time data of transient formation energy during the overflow process based on the derivative of the standpressure data, the overflow formation pressure coefficient, the drilling fluid density change characteristics, and the real-time inlet flow rate data during the overflow process, thereby further obtaining the average formation energy.

[0011] Preferably, the step of evaluating the formation energy level during the overflow process based on the average formation energy includes: analyzing the formation energy level range and the corresponding overflow situation based on the average formation energy and using a preset formation energy evaluation level, so as to select an appropriate well control method based on the analysis results.

[0012] On the other hand, the present invention also provides a system for quantitatively evaluating the formation energy of a blowout, comprising: an annular flow rate generation module configured to calculate real-time annular flow rate data based on real-time data of the change in total pool volume before and after blowout shut-in; an intrusion fluid proportion generation module configured to calculate real-time proportion characteristic data of the intrusion fluid occupying the annular space based on the real-time annular flow rate data, combined with the drill string assembly and wellbore structure; an intrusion fluid density generation module configured to acquire real-time data of standpipe pressure and casing pressure before and after blowout shut-in, and calculate the intrusion fluid density based on the real-time proportion characteristic data; an average formation energy generation module configured to calculate the average formation energy of the blowout process based on the real-time standpipe pressure data and the intrusion fluid density; and a formation energy evaluation module configured to perform a grade evaluation of the formation energy during the blowout process based on the average formation energy.

[0013] Preferably, the system further includes an overflow start time determination module, wherein the overflow start time determination module comprises: an effective time period filtering unit configured to determine a specified time period from a first time specified before overflow shut-in to the shut-in time; a drilling engineering basic parameter filtering unit configured to acquire real-time dynamic data of standpipe pressure, casing pressure, suspended weight, outlet flow rate and total pool flow rate within the specified time period, and to identify the change time corresponding to each dynamic data; and a start time generation unit configured to determine the actual start time of the overflow based on the change time of each parameter.

[0014] Preferably, the annular flow generation module includes: an overflow velocity calculation unit configured to calculate the real-time overflow velocity of the intruding fluid during the overflow process formed from the actual start time of the overflow to the shut-in time; and an annular flow calculation unit configured to obtain the real-time flow data of the annulus based on the real-time overflow velocity of the intruding fluid and the real-time dynamic data of the inlet flow rate during the overflow process.

[0015] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0016] This invention discloses a method and system for quantitatively evaluating the energy of a blowout formation. The method and system are based on a calculation model of basic parameters of the invading fluid established by the change in total well volume; a method for calculating the average formation energy of the blowout process established based on the basic parameters of the invading fluid, wellbore structure data, drill string structure data, and real-time standpipe pressure change data; and a formation energy level classification scheme established based on the formation energy. To ensure the success of well control operations in deep and ultra-deep wells and improve the success rate of well control, this invention rapidly and effectively calculates the formation energy quantitatively by applying the above-mentioned blowout formation energy evaluation scheme, accurately determines the energy level of the formation, and provides a basis for the appropriate selection of well control methods.

[0017] 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

[0018] 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:

[0019] Figure 1 This is a step diagram of a method for quantitatively evaluating the energy of an overflow formation according to an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of a specific process in the method for quantitatively evaluating the energy of overflow formations according to an embodiment of this application.

[0021] Figure 3 This is a schematic diagram of the vertical pressure change curve in a first example of a method for quantitatively evaluating the energy of an overflow formation according to embodiments of this application.

[0022] Figure 4 This is a schematic diagram of the total pool volume change curve in a first example of a method for quantitatively evaluating overflow formation energy in an embodiment of this application.

[0023] Figure 5 This is a schematic diagram of the inlet flow rate variation curve in a first example of a method for quantitatively evaluating overflow formation energy according to embodiments of this application.

[0024] Figure 6 This is a block diagram of a system for quantitatively evaluating the energy of overflow formations, according to an embodiment of this application. Detailed Implementation

[0025] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various embodiments and features in the various embodiments 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.

[0026] Furthermore, the steps illustrated in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowcharts, in some cases the steps shown or described may be performed in a different order than that shown here.

[0027] With the increasing demand for oil and gas resources from my country's economy and society, oil and gas exploration and development are gradually moving towards deep and complex reservoirs, such as the Sichuan Basin and the Tarim Basin, which contain abundant oil and gas resources in their deep strata. Due to the extremely deep burial of resources, extremely high bottom-hole pressure and temperature, and complex geological conditions in these areas, a series of drilling challenges have arisen, especially well control safety issues.

[0028] For deep-buried marine carbonate reservoirs, the reservoir space is mainly composed of pores and fractures, making them prone to gas-liquid displacement, prolonged circulation and degassing times, and overflows during drilling. Due to a lack of understanding of formation energy, it is difficult to quickly and accurately select a suitable well control method after an overflow occurs, leading to overflow well control failures, prolonged non-drilling time, and increased drilling costs.

[0029] Current technologies primarily focus on calculating and analyzing formation pressure in overflow formations, lacking a quantitative evaluation scheme for overflow formation energy. Therefore, existing technologies need to provide a quantitative evaluation scheme for overflow formations based on the variation characteristics of engineering feature parameters. This scheme would enable quantitative classification of formation energy, thereby providing technical guidance for overflow well control.

[0030] Therefore, in order to solve one or more of the above-mentioned technical problems, this application proposes a method and system for quantitatively evaluating the formation energy of a blowout. The method and system include: (1) firstly acquiring basic drilling engineering parameters and well shut-in riser pressure data before the blowout, and preprocessing the data; (2) calculating basic parameters of the formation intrusion fluid based on the engineering parameters before and after well shut-in; (3) calculating the formation energy magnitude based on the blowout fluid parameters and well shut-in engineering parameters; and (4) performing energy analysis and evaluation based on the formation energy magnitude. In this way, the present invention can comprehensively judge the magnitude of formation energy by analyzing the response characteristics of engineering logging parameters during the period from the blowout to well shut-in and after well shut-in, so as to quantitatively identify the formation energy, provide theoretical support for the selection of well control methods, and thus meet the technical requirements for safe construction of deep and ultra-deep gas intrusion control wells.

[0031] Example 1

[0032] Figure 1 This is a step diagram illustrating a method for quantitatively evaluating the energy of an overflow formation according to an embodiment of this application. Figure 1 As shown in the embodiments of the present invention, the method for quantitatively evaluating the energy of overflow formations (hereinafter referred to as the "overflow formation energy evaluation method") includes at least the following steps.

[0033] Step S110 calculates the real-time flow data of the annulus based on the real-time data of the total pool volume change before and after the overflow well shut-in. In step S110, it is necessary to determine the first time point (specified) corresponding to the first time period before the well shut-in time after the overflow phenomenon occurs, and the second time point corresponding to the well shut-in time, based on the start time of the overflow phenomenon of the well to be evaluated. Then, a specified time period is formed between the first time point and the second time point. After that, the real-time flow data of the annulus within the specified time period (i.e., the annulus flow value at each time point within the specified time period) is obtained.

[0034] Step S120 calculates the real-time proportion of the annular space occupied by the invading fluid after the overflow occurs based on the real-time annular flow data obtained in step S110, combined with the drill string assembly information, well structure and the (real-time) well inclination data corresponding to the specified time period, and based on the aforementioned data and information. (i.e., the proportion of the annular space occupied by the invading fluid at each moment within the specified time period.)

[0035] Step S130 acquires real-time riser pressure data and real-time casing pressure data before and after the overflow shut-in, and calculates the intrusion fluid density by combining the real-time proportion characteristic data obtained in step S120. In step S130, firstly, real-time riser pressure data (real-time riser pressure data) and real-time casing pressure data corresponding to the specified time period are acquired. Then, based on the proportion characteristic of the intrusion fluid occupying the annulus space obtained in step S120, the actual density data of the intrusion fluid is calculated.

[0036] Next, step S140 will calculate the real-time data of transient formation energy during the overflow process (i.e., calculate the real-time dynamic change data of the formation transient energy at each overflow moment during the overflow process) based on the real-time vertical pressure data obtained in step S130 and the calculated intrusion fluid density, thereby obtaining the average formation energy.

[0037] Finally, step S150 evaluates the formation energy level corresponding to the entire overflow process based on the average formation energy obtained in step S140. Therefore, this embodiment of the invention utilizes steps S110 to S150 to quickly and effectively quantitatively calculate formation energy, accurately using the average formation energy to evaluate the formation energy level during the overflow process, providing a basis for selecting the well control method after the overflow.

[0038] Figure 2 This is a schematic flowchart illustrating a method for quantitatively evaluating the energy of an overflow formation according to an embodiment of this application. See below for reference. Figure 2 The process of the overflow formation energy assessment method described in the embodiments of the present invention will be explained in detail below.

[0039] Before obtaining the various data required for the formation evaluation scheme, this invention needs to accurately determine the specific start time of the overflow phenomenon using steps S201 to S203. For example... Figure 2 As shown, step S201 determines the first (specified) moment before the actual shut-in moment corresponding to the start time of the overflow phenomenon in the well to be evaluated, and the second moment corresponding to the shut-in moment, and further determines the specified time period between the first moment and the second moment, thereby taking the current specified time period as the occurrence stage of the overflow process, i.e., the overflow stage. For example, the above-mentioned specified time period is the time period formed from 2 hours before the overflow shut-in to the shut-in moment.

[0040] Then, step S202 acquires the real-time dynamic change data of vertical pressure, sheathing pressure, suspended weight, outlet flow, and total pool flow within the specified time period, and identifies the change time corresponding to each dynamic data. That is, in step S202, the dynamic change data (sequence) of vertical pressure, sheathing pressure, suspended weight, outlet flow, and total pool flow corresponding to each overflow time within the entire overflow stage are first obtained. The time corresponding to the significant change in each data sequence (data change time) is identified, thereby determining the times T1, T2, T3, T4, and T5 when the vertical pressure, sheathing pressure, suspended weight, outlet flow, and total pool volume change before and after the overflow. In this embodiment of the invention, the overflow time is a plurality of time points formed by dividing the specified time period according to a preset overflow time interval (e.g., a time interval less than 10 seconds).

[0041] Next, step S203 determines the actual start time of the overflow phenomenon based on the change times of various parameters corresponding to the entire overflow process obtained in step S202. In step S203, the earliest time from the data change times of various parameters needs to be selected as the start time T0 of the overflow.

[0042] Continue to refer to Figure 2 Step S204 calculates the real-time overflow velocity of the intruding fluid during the overflow process from the actual overflow start time T0 to the well shut-in time T. In step S204, the specified time period corresponding to the total overflow stage can be determined as t, with T0 as the start time and the successful well shut-in time T as the end time, i.e., t = T - T0. Then, based on the real-time dynamic change data of the total pool volume change corresponding to the overflow stage, the total pool volume increment V corresponding to each overflow time is calculated. influx(That is, the increment of the total pool volume corresponding to the next overflow time from the current overflow time to the total pool volume corresponding to the current overflow time), and simultaneously, calculate the overflow rate of the intruding fluid. The real-time overflow rate of the intruding fluid is calculated using the following expression:

[0043]

[0044] Where i represents the sequence number corresponding to each overflow time interval, Q influx,i V represents the overflow rate corresponding to the i-th overflow time interval (i.e., the overflow rate within the i-th unit time interval). influx,i This represents the increment of the total pool volume corresponding to the i-th overflow time interval, where t represents the time period (specified time period) corresponding to the total overflow phase. i t i+1 These represent the adjacent overflow times corresponding to the i-th overflow time interval, Indicates the overflow time t i+1 The corresponding total pool volume, Overflow time t i The corresponding total pool volume.

[0045] Additionally, in step S204, real-time dynamic data of the inlet flow rate (real-time inlet flow rate data) and the outlet flow rate (real-time outlet flow rate data) corresponding to the current overflow stage can be obtained first, and can be directly calculated using the difference between the outlet flow rate and the inlet flow rate. This embodiment of the invention does not specifically limit the calculation method for the real-time overflow rate; those skilled in the art can select the appropriate method based on the actual sensor configuration.

[0046] After calculating the real-time overflow rate, step S205 obtains the real-time dynamic data of the inlet flow at each moment during the entire overflow phase and organizes it into the following array (Q in,i , Δt i Then, based on the real-time overflow velocity of the invading fluid calculated in step S204, the real-time annular flow rate Q corresponding to the formation fluid invading the annulus in the wellbore after the overflow occurs is obtained. a,i Therefore, the array of annular flow changes over time (real-time annular flow array) can be represented as (Q a,i , Δt i The real-time annular flow data is calculated using the following expression, thereby calculating the corresponding annular flow data for each overflow time interval within the overflow phase:

[0047] Q a,i =Q in,i +Q influx，i (2)

[0048] Among them, Q a,iQ represents the annular flow data corresponding to the i-th overflow time interval (i.e., the annular flow within a unit time interval i), in,i This represents the inlet flow rate data corresponding to the i-th overflow time interval (i.e., the wellbore inlet flow rate within a unit time interval i). Therefore, in step S205, the real-time overflow velocity is added to the real-time flow rate data at the wellbore inlet according to the overflow time interval to obtain the real-time annular flow rate data, which then proceeds to step S206.

[0049] Step S206 calculates the real-time volume data of the mixed fluid in the annulus during the overflow process based on the real-time annular flow rate data obtained in step S205. That is, in step S206, after the overflow occurs and the intruding fluid enters the wellbore and forms a mixed fluid in the annulus, it is necessary to calculate the real-time volume data of the mixed fluid in the annulus corresponding to each overflow time interval during the overflow phase. The real-time volume data of the mixed fluid is calculated using the following expression:

[0050] V a,i =Q a,i ×Δt i (3)

[0051] Among them, V a,i This represents the volume data of the mixed fluid in the annulus corresponding to the i-th overflow time interval (i.e., the volume of the mixed fluid in the annulus within a unit time interval i), Δt. i This represents the time period corresponding to the overflow time interval i.

[0052] Step S207 obtains an annular size distribution feature structure array based on the drill string assembly information and wellbore structure information corresponding to the current well to be evaluated. In step S207, an annular wellbore size structure array from bottom to top is generated based on the wellbore structure and drill string structure information (in this embodiment of the invention, the annular wellbore is divided into j segments from bottom to top), and is represented by the following expression:

[0053]

[0054] Where Annular represents the annular wellbore size structure array of the current well to be evaluated, j represents the total number of segments in the current wellbore, L1, L2...L j This represents the length of each section of the wellbore in the current well to be evaluated, ID1, ID2, ... ID j These represent the annular inner diameter (i.e., the outer diameter of the drill string assembly for the corresponding well section) of each section of the well to be evaluated, OD1, OD2...OD jThese represent the annular outer diameter of each section of the wellbore in the current evaluation well. Specifically, if the corresponding well section in the evaluation well is a casing section, then the annular outer diameter of the current wellbore is the inner diameter of the casing of the corresponding casing section; if the corresponding well section in the evaluation well is an open hole section, then the annular outer diameter of the current wellbore is the product of the drill bit diameter and the wellbore enlargement correction factor.

[0055] Further, after forming the annular wellbore size structure array for the current well to be evaluated, the process proceeds to step S208. Step S208 calculates the volume fraction of the annular space occupied by the mixed fluid at each gas intrusion overflow moment (corresponding to each gas intrusion overflow time interval) and the vertical length occupied by the mixed fluid based on the real-time volume data of the mixed fluid calculated in step S206, the annular size distribution characteristic structure array formed in step S207, and the real-time well inclination data corresponding to the entire overflow stage obtained from well logging, thereby obtaining the real-time proportion characteristic data.

[0056] In step S208, based on the real-time volume data of the mixed fluid obtained in step S206 and the annular size distribution characteristic structure array formed in step S207, the length of the mixed fluid occupying the well axis in each time interval during the process from T0 to T, and the volume fraction of the annular space occupied by the mixed fluid in that time interval, are calculated and expressed using the following expression:

[0057]

[0058] Where k represents the total number of overflow time intervals within the overflow phase, l1, l2, ..., l k f1, f2, ..., fk represent the lengths (well axis) occupied by the mixed fluid along the wellbore length corresponding to the 1st, 2nd, ..., kth overflow time intervals, respectively. k These represent the volume fractions of the annular space occupied by the mixed fluid corresponding to the 1st, 2nd...kth overflow time intervals, respectively. Therefore, it can be seen that the ratio of the annular flow rate corresponding to the i-th overflow time interval to the flow rate data at the wellbore inlet can be used to calculate the length occupied by the mixed fluid along the well axis during the i-th overflow time interval and the volume fraction of the annular space occupied by the mixed fluid during that time interval.

[0059] Then, based on the wellbore deviation data obtained during the measurement while drilling process, and combined with the above expression (5), the vertical length occupied by the mixed fluid in each overflow time interval is calculated to obtain real-time proportion characteristic data. The proportion characteristic data corresponding to each overflow time interval includes at least: the length of the annular space occupied by the mixed fluid in the vertical direction, and the volume fraction of the wellbore annular space occupied by the mixed fluid in that time interval. Specifically, the vertical distance of the mixed fluid occupying the formation in the vertical direction during each time interval from T0 to T is calculated using the following expression:

[0060]

[0061] Among them, V influx,i This represents real-time percentage feature data, H1, H2, ..., H k These represent the vertical lengths occupied by the mixed fluid along the vertical direction corresponding to the 1st, 2nd...kth overflow time intervals, respectively.

[0062] After obtaining the real-time percentage characteristic data, the process proceeds to step S209. Step S209 determines the drilling fluid density change characteristics during the overflow process based on the original drilling fluid density (i.e., the drilling fluid density under normal temperature and pressure conditions) and drilling fluid rheological characteristics, combined with real-time standpipe pressure data and real-time casing pressure data during the overflow process. Thus, the drilling fluid density data corresponding to each overflow time interval can be obtained through the drilling fluid density change characteristics.

[0063] Then, step S210, based on the standpipe pressure and casing pressure data corresponding to each overflow moment (each overflow time interval) throughout the entire overflow stage obtained in step S209, and combining the drilling fluid density change characteristics obtained in step S209, and the real-time proportion characteristic data obtained in step S208, obtains the intrusion fluid density from the standpipe pressure and casing pressure data corresponding to the shut-in moment, thus obtaining the intrusion fluid density data. The intrusion fluid density is calculated using the following expression:

[0064]

[0065] ΔP h =WHP S -SPP s (8)

[0066] Where, ρ i WHP represents the density of the infiltrating fluid. s SPP represents the casing pressure data corresponding to the shut-in time. s ρ represents the stand pressure data corresponding to the well shut-in time. m,i Let represent the drilling fluid density corresponding to the i-th overflow time interval, and g represent the gravitational acceleration.

[0067] Therefore, the embodiment of the present invention uses the above expressions (1) to (8) to obtain the density data of the intruding fluid, which provides a basis for the subsequent calculation of formation energy, and thus proceeds to step S211.

[0068] Step S211 calculates the derivative of the vertical pressure data corresponding to each gas intrusion overflow time interval based on the real-time vertical pressure data during the overflow process. In step S211, based on the vertical pressure data corresponding to each gas intrusion overflow time interval during the entire overflow phase, the time derivative of the vertical pressure data corresponding to each gas intrusion overflow time interval is calculated using the following expression:

[0069]

[0070] in, SPP represents the time derivative of the vertical pressure data corresponding to the i-th overflow time interval. i+1 SPP i This represents the stand pressure data corresponding to the i-th and (i+1)-th overflow time intervals, respectively. Then, proceed to step S212. Step S212 determines the overflow formation pressure coefficient based on the stand pressure data, casing pressure data, and drilling fluid density data at the shut-in time, thus proceeding to step S213.

[0071] Step S213 calculates the real-time data of transient formation energy during the overflow process based on the derivative of the real-time standpressure data obtained in step S211, the overflow formation pressure coefficient obtained in step S212, the drilling fluid density change characteristics obtained in step S209, and the real-time inlet flow rate data throughout the overflow stage. This further yields the average formation energy used for quantitative evaluation of formation energy during the overflow process. Specifically, the transient formation energy data corresponding to each overflow time interval during the entire overflow stage is calculated using the following expression:

[0072]

[0073] Among them, R i ρ represents the transient formation energy data corresponding to the i-th overflow time interval. p This represents the overflow formation pressure coefficient. Furthermore, the average formation energy corresponding to the current overflow process is calculated using the following expression:

[0074]

[0075] Where R represents the average formation energy. Thus, in this embodiment of the invention, the transient formation energy data corresponding to each overflow time interval are weighted and averaged to obtain the average formation energy used for overflow formation energy analysis of the current well to be evaluated.

[0076] Step S214: Based on the average formation energy obtained in step S213, analyze the formation energy level range and corresponding overflow situation using the preset formation energy evaluation level, so as to select an appropriate well control method based on the analysis results.

[0077] In this embodiment of the invention, based on the magnitude of the formation energy and the situation of the formation overflow, the formation energy corresponding to the actual overflow is divided into 5 levels, as shown in Table 1 below. Table 1 is a formation energy level evaluation table, which divides the formation energy at the time of overflow from low to high as follows: extremely low formation energy (level 1 formation energy), relatively low formation energy (level 2 formation energy), relatively high formation energy (level 3 formation energy), high formation energy (level 4 formation energy), and enormous formation energy (level 5 formation energy).

[0078] Table 1 Formation Energy Level Evaluation Table

[0079]

[0080] As shown in Table 1, when the mean formation energy is greater than 0 and less than or equal to 10, the formation energy corresponding to the current overflow phenomenon belongs to the first-level formation energy. At this level, the formation energy is extremely low, the overflow fluid is usually oil or water, and the bottomhole pressure differential is small when the overflow occurs, resulting in a slow fluid invasion rate. In this case, under the current first-level formation energy, the driller's method can be used directly to control the well.

[0081] When the average formation energy is greater than 10 and less than or equal to 100, the formation energy corresponding to the current overflow phenomenon belongs to the second-level formation energy. At this level, the formation energy is low, usually indicating gas invasion from low-permeability reservoirs or oil-water invasion from high-permeability formations. In this case, well control can be achieved using the driller's method or the engineer's method at the current second-level formation energy level.

[0082] When the average formation energy is between 100 and 500, the current overflow phenomenon corresponds to a Class III formation energy. At this level, the formation energy is relatively high, and the overflow fluid is typically gas or a mixture of oil and gas. In this case, at the current Class III formation energy, if the formation contains hydrogen sulfide, the pressure-back method can be used directly; if it does not contain hydrogen sulfide at the Class III formation energy, the formation pressure coefficient needs to be determined by shut-in pressure testing, and the engineer's method is recommended.

[0083] When the average formation energy is between 500 and 1000, the current overflow phenomenon corresponds to a fourth-level formation energy. At this level, the formation energy is high, the overflow fluid is primarily gas, the formation pressure is high, and the bottomhole pressure differential is large. In this case, under the current fourth-level formation energy, if the formation contains hydrogen sulfide and the actual conditions (drill string anti-sulfur performance, wellbore structure) meet the anti-sulfur requirements, the engineer's method of well control can be directly used. If hydrogen sulfide is present but the actual conditions do not meet the anti-sulfur requirements, the pressure-back method of well control should be used. Alternatively, if hydrogen sulfide is not present, under the fourth-level formation energy, the engineer's method and the replacement method can be used for well control.

[0084] When the average formation energy is greater than 1000, the current overflow phenomenon corresponds to the fifth-level formation energy. At this level, the formation energy is enormous, the overflow fluid is gas, the formation pressure is high, the bottomhole pressure differential is large, and the fluid invasion rate is fast. At this level, if the formation contains hydrogen sulfide and the actual conditions (drill string anti-sulfur performance, wellbore structure) meet the anti-sulfur requirements, the engineer's method or replacement method can be used directly for well control. If hydrogen sulfide is present but the actual conditions do not meet the anti-sulfur requirements, the pressure-back method should be used for well control. Alternatively, if hydrogen sulfide is not present, the engineer's method should be used for well control at the fifth-level formation energy. If the formation energy at this level is too high, adjustments should be made in a timely manner based on the wellhead casing pressure when using the engineer's method or replacement method for well control, and preparations for blowout relief and depressurization should be made, with an automatic surface ignition device readily available.

[0085] Example 2

[0086] The following describes the specific implementation process of the overflow formation energy assessment method of the present invention by applying the overflow formation energy assessment scheme described in Embodiment 1 of the present invention to a certain well X. The specific process is as follows:

[0087] (1) Calculate the basic parameters of the intruding fluid:

[0088] Analysis was conducted using data from well X. The wellbore structure data is as follows:

[0089] First section: 406.4mm×1507.7m / 479.4mm×1508m

[0090] Second section: 298.5mm×4891.85m / 374.65mm×4894m

[0091] Three sections: 219.1mm×4712m+226.24mm×6420m / 269.9mm×6420m

[0092] Quarter sheet: 168.3mm × (6325-7350m) / 190.5 × 7351m

[0093] Five-panel: 143.9mm × 7636.50m (diagonal) / 7541.71m (vertical)

[0094] The drill string assembly data is as follows: 143.9mm PDC drill bit + 1.75° screw + float valve + non-magnetic drill collar + non-magnetic suspension + 36 88.9mm drill pipes + 45 88.9mm heavy-duty drill pipes + 88.9mm drill pipe + 311*DS400 + 114.3mm drill pipe.

[0095] The curves corresponding to the real-time vertical pressure data, real-time total pool volume data, and real-time inlet flow rate data of a certain well X are as follows: Figure 3 ( Figure 3 (This is a schematic diagram of the vertical pressure change curve in the first example of the method for quantitatively evaluating the energy of an overflow formation according to embodiments of this application.) Figure 4 ( Figure 4 (This is a schematic diagram of the total pool volume change curve in a first example of a method for quantitatively evaluating overflow formation energy in embodiments of this application) and Figure 5 As shown ( Figure 5 This is a schematic diagram of the inlet flow rate variation curve in a first example of a method for quantitatively evaluating overflow formation energy according to embodiments of this application.

[0096] After the overflow of well X began, the total pool volume, inlet flow rate, annular flow rate, and proportion of intruding fluid are shown in the table below.

[0097] Table 2 shows the total pool volume, inlet flow rate, annular flow rate, and percentage of intrusive fluid.

[0098]

[0099]

[0100]

[0101] Furthermore, based on the total pool volume, inlet flow rate, wellbore structure, and drill string assembly, the calculated fluid density of the intruding fluid is 0.201 g / cm³. 3 .

[0102] (2) Calculate formation energy:

[0103] The formation energy results calculated using vertical pressure changes and inlet flow data are shown below:

[0104] Table 3 shows partial data on vertical pressure, inlet flow rate, and formation energy.

[0105]

[0106]

[0107]

[0108] Furthermore, the average formation energy of well X during the overflow was calculated to be 13.04.

[0109] (3) Formation energy classification evaluation:

[0110] Based on the average formation energy obtained during the overflow, the formation of well X is a second-level formation with relatively low formation energy.

[0111] Example 3

[0112] Based on the overflow formation energy evaluation method described in Embodiments 1 and 2 above, this invention also provides a system for quantitatively evaluating overflow formation energy (hereinafter referred to as "overflow formation energy evaluation system"). Figure 6 This is a block diagram of a system for quantitatively evaluating the energy of overflow formations, according to an embodiment of this application.

[0113] like Figure 6 As shown, the overflow formation energy evaluation system of this invention includes the following modules: annular flow generation module 61, intrusion fluid proportion generation module 62, intrusion fluid density generation module 63, average formation energy generation module 64, and formation energy evaluation module 65. The annular flow generation module 61 is implemented according to the method described in step S110 above, and is configured to calculate the real-time flow data of the annulus based on the real-time data of the change in the total pool volume before and after the overflow shut-in; the intrusion fluid proportion generation module 62 is implemented according to the method described in step S120 above, and is configured to calculate the real-time proportion characteristic data of the intrusion fluid occupying the annular space based on the real-time annular flow data, combined with the drill string assembly and wellbore structure; the intrusion fluid density generation module 63 is implemented according to the method described in step S130 above, and is configured to obtain the real-time data of the standpipe pressure and casing pressure before and after the overflow shut-in, and calculate the intrusion fluid density based on the real-time proportion characteristic data; the average formation energy generation module 64 is implemented according to the method described in step S140 above, and is configured to calculate the average formation energy of the overflow process based on the real-time standpipe pressure data and the intrusion fluid density; the formation energy evaluation module 65 is implemented according to the method described in step S150 above, and is configured to evaluate the formation energy level of the overflow process based on the average formation energy.

[0114] Furthermore, the overflow formation energy assessment system described in this embodiment of the invention also includes an overflow initiation time determination module (unnumbered). This module comprises an effective time period filtering unit, a drilling engineering basic parameter filtering unit, and an initiation time generation unit. Specifically, the effective time period filtering unit is configured to determine a specified time period from the first moment specified before well shut-in to the well shut-in time; the drilling engineering basic parameter filtering unit is configured to acquire real-time dynamic data of standpipe pressure, casing pressure, suspended weight, outlet flow rate, and total pool flow rate within the specified time period, and identify the change times corresponding to each dynamic data point; the initiation time generation unit is configured to determine the actual initiation time of the overflow based on the change times of each parameter.

[0115] The annular flow generation module 61 includes an overflow velocity calculation unit 611 and an annular flow calculation unit 612. The overflow velocity calculation unit 611 is configured to calculate the real-time overflow velocity of the intruding fluid during the overflow process, which occurs from the actual start time of the overflow to the shut-in time. The annular flow calculation unit 612 is configured to obtain the real-time flow data of the annulus based on the real-time overflow velocity of the intruding fluid and the real-time dynamic data of the inlet flow rate during the overflow process.

[0116] This invention discloses a method and system for quantitatively evaluating the energy of a blowout formation. The method and system are based on a calculation model of basic parameters of the invading fluid established by the change in total well volume; a method for calculating the average formation energy of the blowout process established based on the basic parameters of the invading fluid, wellbore structure data, drill string structure data, and real-time logging standpressure change data; and a formation energy level classification scheme established based on the formation energy. To ensure the success of well control operations in deep and ultra-deep wells and improve the success rate of well control, this invention rapidly and effectively calculates the formation energy quantitatively by applying the above-mentioned blowout formation energy evaluation scheme, accurately determines the energy level of the formation, and provides a basis for the appropriate selection of well control methods.

[0117] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0118] 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.

[0119] The phrase "an embodiment" or "an embodiment" used in this specification means that a particular 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" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0120] 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 quantitatively evaluating the energy of an overflow formation, characterized in that, include: Calculate the real-time flow rate of the annulus based on the real-time data of the total pool volume change before and after the overflow well is shut off; Based on real-time annular flow data, combined with drill string assembly and wellbore structure, the real-time proportion of the annular space occupied by the invading fluid is calculated. Obtain real-time data on stand pressure and casing pressure before and after well shut-in due to overflow, and calculate the intrusion fluid density by combining the real-time percentage characteristic data; Based on real-time standpressure data and the density of the invading fluid, the average formation energy during the overflow process is calculated, including: calculating the derivative of the standpressure data corresponding to each gas intrusion overflow time interval based on the real-time standpressure data during the overflow process; determining the overflow formation pressure coefficient based on the standpressure data, casing pressure data, and drilling fluid density data at the shut-in time; and calculating real-time data of transient formation energy during the overflow process based on the derivative of the standpressure data, the overflow formation pressure coefficient, the drilling fluid density change characteristics, and the real-time inlet flow rate data during the overflow process, thereby obtaining the average formation energy. The formation energy level during the overflow process is evaluated based on the average formation energy.

2. The method according to claim 1, characterized in that, Before the step of calculating the real-time flow rate data of the annulus based on real-time data of the total pool volume change before and after overflow shut-off, the method includes: Determine the specified time period from the first moment before the overflow well is shut off to the time of well shut-off; Acquire real-time dynamic data of vertical pressure, sleeve pressure, suspended weight, outlet flow rate and total pool flow rate within the specified time period, and identify the change time corresponding to each dynamic data item; The actual start time of the overflow is determined based on the changes in various parameters.

3. The method according to claim 1, characterized in that, The step of calculating the real-time flow rate of the annulus based on real-time data of the total pool volume change before and after overflow shut-off includes: Calculate the real-time overflow velocity of the intruding fluid during the overflow process from the actual start of the overflow to the time of well shut-in; The real-time flow data of the annulus is obtained based on the real-time overflow velocity of the intruding fluid and the real-time dynamic data of the inlet flow rate during the overflow process.

4. The method according to any one of claims 1 to 3, characterized in that, The step of calculating the real-time proportion of the annular space occupied by invading fluid based on real-time annular flow data, combined with drill string assembly and wellbore structure, includes: Based on the real-time annular flow data, calculate the real-time volume data of the mixed fluid in the annulus during the overflow process; Based on the drill string assembly and the wellbore structure, an array of annular size distribution characteristics is obtained; Based on the real-time volume data of the mixed fluid, the annular size distribution characteristic structure array, and the well inclination data, the volume fraction of the mixed fluid occupying the annular space and the vertical length it occupies at each gas intrusion overflow moment are calculated to obtain the real-time proportion characteristic data.

5. The method according to claim 4, characterized in that, The calculation of the density of the intruding fluid includes: Based on the original density and rheological characteristics of the drilling fluid, combined with the real-time stand pressure data and real-time casing pressure data during the overflow process, the characteristics of the drilling fluid density change during the overflow process are determined. Based on the real-time stand pressure data, the real-time casing pressure data, the drilling fluid density change characteristics, and the real-time proportion characteristics data, the intrusion fluid density is obtained from the stand pressure data and casing pressure data corresponding to the shut-in time.

6. The method according to any one of claims 1 to 3, characterized in that, The step of evaluating the formation energy level during the overflow process based on the average formation energy includes: Based on the average formation energy, the formation energy level range and corresponding overflow situation are analyzed using a preset formation energy evaluation level, so as to select an appropriate well control method based on the analysis results.

7. A system for quantitatively evaluating the energy of an overflow formation, characterized in that, include: The annular flow generation module is configured to calculate the real-time flow data of the annulus based on the real-time data of the change in total pool volume before and after the overflow well is shut off. The intrusion fluid percentage generation module is configured to calculate the real-time percentage characteristic data of the intrusion fluid occupying the annulus space based on real-time annular flow data, combined with the drill string assembly and well structure. The intrusion fluid density generation module is configured to acquire real-time data of standpipe pressure and casing pressure before and after overflow shut-in, and calculate the intrusion fluid density by combining the real-time proportion feature data. The average formation energy generation module is configured to calculate the average formation energy during the overflow process based on real-time standpressure data and the density of the invading fluid. This includes: calculating the derivative of the standpressure data corresponding to each gas intrusion overflow time interval based on the real-time standpressure data during the overflow process; determining the overflow formation pressure coefficient based on the standpressure data, casing pressure data, and drilling fluid density data at the well shut-in time; and calculating real-time data of transient formation energy during the overflow process based on the derivative of the standpressure data, the overflow formation pressure coefficient, the drilling fluid density change characteristics, and the real-time inlet flow rate data during the overflow process, thereby obtaining the average formation energy. The formation energy assessment module is configured to assess the formation energy level during the overflow process based on the average formation energy.

8. The system according to claim 7, characterized in that, The system further includes an overflow start time determination module, wherein the overflow start time determination module comprises: The effective time period filtering unit is configured to determine the specified time period from the first moment specified before the overflow well shut-in to the well shut-in time. The drilling engineering basic parameter screening unit is configured to acquire real-time dynamic data of stand pressure, casing pressure, suspended weight, outlet flow rate and total pool flow rate within the specified time period, and identify the change time corresponding to each dynamic data. The start time generation unit is configured to determine the actual start time of the overflow based on the changes in various parameters.

9. The system according to claim 7, characterized in that, The annular flow generation module includes: The overflow velocity calculation unit is configured to calculate the real-time overflow velocity of the intruding fluid during the overflow process, which occurs from the actual start of the overflow to the shut-in time. The annular flow calculation unit is configured to obtain the real-time flow data of the annulus based on the real-time overflow velocity of the intruding fluid and the real-time dynamic data of the inlet flow rate during the overflow process.

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