Early detection method of lost circulation based on downhole engineering parameter measurement

Abstract

The invention relates to a well leakage detection method in the field of oil drilling, in particular to an early well leakage detection method based on downhole engineering parameter measurement, which can timely detect early well leakage according to the change of downhole engineering parameters measured while drilling when leakage occurs, and reduce the physical leakage loss of mud. The specific steps include: step one, data collection, preliminarily determining the depth range and lithology of leakage occurrence; step two, according to the flow characteristics when well leakage occurs, a well leakage characteristic parameter calculation model, and simulating and calculating the characteristic parameter diagram when leakage occurs and the characteristic parameter diagram during normal drilling according to ground input data; step three, obtaining real-time characteristic parameters; using downhole drilling data measured by a while drilling measurement system, inputting it into software to form a real-time data monitoring diagram; step four, determining leakage judgment criteria; arranging and drawing a comparison diagram of measurement and prediction parameters according to the data obtained in the above steps one to three, and performing leakage judgment, early warning and alarm on the results.

Description

Technical Field

[0001] The invention relates to a well leakage detection method in the field of petroleum drilling, in particular to an early well leakage detection method based on downhole engineering parameter measurement. Background Art

[0002] Well leakage is a complex underground situation in which various working fluids (including drilling fluid, cement slurry, and completion fluid) flow into the formation under the action of pressure difference during drilling and underground operations. It is one of the most common and common technical problems in the drilling process. Well leakage is very harmful: well leakage causes a large amount of working fluid to leak into the formation, directly causing huge material losses, delaying drilling time, and extending the drilling cycle; well leakage will also damage the production capacity of the reservoir, interfere with geological logging work, and even cause various underground complex situations such as stuck drill, blowout, and well collapse. Therefore, early detection and identification of well leakage is of great significance.

[0003] At present, there are two main types of leaking layer identification technologies that are widely used: the first is the observation experience method, which is mainly used at the drilling construction site, that is, it is mainly through direct observation of drilling, cuttings logging, drilling fluid level changes, combined with the pump volume parameters during drilling and the changes in drilling fluid performance during well pressure and well testing, and comprehensive analysis to determine the location and properties of the leaking layer. However, this method is suitable for formations with a single leaking layer and a simple open hole section pressure system. For formations with multiple pressure layers and complex leaking conditions, the observation experience method is difficult to effectively identify the leaking layer. The second is the hydrodynamic test method. The basic principle of the hydrodynamic test method is the hydrodynamic characteristics of the well leakage on the drilling fluid circulation, such as the change of the drilling fluid annulus return velocity and the change of the riser pressure. Based on this hydrodynamic characteristic, relevant scholars have studied the drilling fluid positive and reverse circulation test method, the drilling fluid delay time calculation method, and the pump pressure (riser pressure) change test method before and after the well leakage for identification. This method can identify well leakage more accurately, but because the hydrodynamic characteristics are greatly affected by the performance of the drilling fluid and are limited by the flow rate of the drilling fluid, the response and measurement time is long, which affects the timely treatment of well leakage and causes losses. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art, based on the real-time measurement capability of the downhole engineering parameter measurement system, effectively obtain the downhole inner pipe pressure, annulus pressure, and annulus temperature, and combine the simulation values ​​calculated based on the ground injection parameters to perform comparative analysis and identify well leakage, and provide an early detection method for well leakage based on downhole engineering parameter measurement, which can quickly identify well leakage and provide a basis for early treatment of well leakage.

[0005] The technical solution is as follows:

[0006] The early detection method of well leakage based on downhole engineering parameter measurement includes the following specific steps:

[0007] Step 1: Data collection, preliminary determination of the depth range and lithology of the leakage; Based on the well history data and comprehensive logging data, preliminary determination of the depth range of leakage and the lithology developed within the depth range;

[0008] Step 2: According to the flow characteristics when the well leakage occurs, a wellbore parameter calculation model is established, especially a well leakage characteristic parameter calculation model, to provide a theoretical basis for the wellbore parameter calculation;

[0009] Based on the calculation model of well leakage parameters, the characteristic parameter diagram when leakage occurs and the characteristic parameter diagram during normal drilling are simulated and calculated according to the ground input data; the simulation calculation includes the calculation of leakage velocity, the calculation of wellbore pressure when leakage occurs, and the calculation of internal and external pressure difference when leakage occurs;

[0010] Step 3: Obtain real-time characteristic parameters; use the downhole drilling data measured by the drilling measurement system to input the software to form a real-time data monitoring chart;

[0011] Step 4: Determine the missing judgment criteria; draw a comparison chart of the measured and predicted parameters based on the data obtained in the above steps 1 to 3, and perform missing judgment, early warning and alarm on the results.

[0012] Preferably, the specific explanation and calculation process in step 1 are as follows:

[0013] ① Calculation of leakage velocity

[0014] The leakage rate is calculated by intersecting the annular pressure calculation equations above and below the leakage point, and the pressure calculation equation group above and below the leakage point is:

[0015]

[0016]

[0017] Q 排量 =Q 漏失排量 +Q 漏点以上排量 (3)

[0018]

[0019]

[0020]

[0021] In the formula

[0022] P 环空漏点 is the annular pressure at the leak point, MPa;

[0023] P 地层压力 is the formation pressure at the leak point, MPa;

[0024] It is the sum of the annular friction above the leak point, MPa;

[0025] v 排量 is the annular velocity below the leak, m / s;

[0026] v 漏失速度 is the leakage velocity at the leak point, m / s;

[0027] v 漏点以上环空速度 is the annular velocity above the leak point, m / s;

[0028] ρ is the drilling fluid density, kg / m 3 ;

[0029] H 漏深 is the well depth of the leak, m;

[0030] g is the acceleration due to gravity, m / s 2 .

[0031] Q 排量 is the ground input displacement, m 3 / s;

[0032] Q 漏失排量 is the flow rate into the formation, m 3 / s;

[0033] Q 漏点以上排量 is the annular flow rate above the leak point, m 3 / s;

[0034] S 环空 is the annular area, m 2 ;

[0035] S 漏点 is the leak area, m 2 .

[0036] Based on the above equation, the leakage velocity is obtained through iterative calculation.

[0037] ②Wellbore pressure calculation

[0038] Inner pipe pressure

[0039]

[0040] Pressure below the annulus leak point

[0041]

[0042] Pressure above annulus leak point

[0043]

[0044]

[0045] In the formula

[0046] ΔP 内管 is the inner tube pressure loss, MPa;

[0047] ΔP 环空漏点以下 is the annular pressure loss below the leak point, MPa;

[0048] ΔP 环空漏点以上 is the annular pressure loss above the leak point, MPa;

[0049] f wl is the friction coefficient, dimensionless;

[0050] D 内管 is the inner tube diameter, m;

[0051] ΔL is the tube length, m;

[0052] n' is the flow pattern index, dimensionless;

[0053] Re g is the Reynolds number, dimensionless.

[0054] Where f wl is the friction coefficient in turbulent flow. The calculation method of the friction coefficient in laminar flow and transitional flow can refer to the relevant monographs on non-Newtonian fluid mechanics.

[0055] ③ Calculation of internal and external pressure difference

[0056] ΔP 井下模拟 =P 内管模拟 -P 环空模拟 (11)

[0057] In the formula

[0058] ΔP 井下模拟 is the simulated internal and external pressure difference, MPa;

[0059] P 内管模拟 is the simulated calculated inner tube pressure, MPa;

[0060] P 环空模拟 is the simulated calculated outer tube pressure, MPa;

[0061] Preferably, the parameters calculated in step 2 according to the ground input data when leakage occurs and during normal drilling include injection displacement, return displacement, injection density, drilling fluid viscosity, dynamic plastic ratio, static shear force, dynamic shear force, six-speed viscometer reading, pump pressure, and vertical pressure.

[0062] Preferably, the monitoring simulation and surface parameter change roadmap in step 2 includes vertical pressure, simulated annular pressure, simulated vertical pressure, and simulated internal and external pressure difference.

[0063] Preferably, the software input in step three forms a real-time data monitoring version including inner tube pressure, annulus pressure, internal and external pressure difference, and annulus temperature.

[0064] Preferably, the internal and external pressure difference calculation formula in step 3 is as follows:

[0065] ΔP 井下测量 =P 内管测量 -P 环空测量 (12)

[0066] Where:

[0067] ΔP 井下测量 is the measured internal and external pressure difference, MPa;

[0068] P 内管测量 is the measured inner tube pressure, MPa;

[0069] P 环空测量 is the measured outer tube pressure, MPa;

[0070] Preferably, in step 4, the leaking layer is identified by obtaining a measurement and prediction comparison diagram, and the specific method for analyzing the leakage mechanism is to judge according to the predicted values ​​and calculated values ​​of the inner pipe and annular pressure and the internal and external pressure difference in the measurement and prediction comparison diagram:

[0071] When P 环空测量 ≈P 环空模拟正常 , normal drilling;

[0072] When P 环空测量 <P 环空模拟正常 :

[0073] If ΔP 井下测量 ≈ΔP 井下模拟 , and the changing trend of the measured annular pressure monitoring diagram is consistent with the annular pressure diagram when the simulated well leakage occurs, and the downhole temperature changes suddenly, it can be considered that the well leakage occurs in the well.

[0074] In the formula

[0075] P 环空模拟正常 It is the outer pipe pressure during simulation and calculation of normal drilling, MPa;

[0076] The beneficial effects of the present invention are:

[0077] Based on the real-time measurement capability of the downhole engineering parameter measurement system, the downhole inner tube pressure, annular pressure, and annular temperature are effectively obtained, and the simulation values ​​calculated based on the surface injection parameters are compared and analyzed to identify the well leakage. This method can quickly identify the well leakage and provide a basis for the formulation of the drilling construction plan and the leakage prevention and plugging plan. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 A flow chart for leak identification according to the method for early detection of well leakage based on downhole engineering parameter measurement of the present invention;

[0079] Figure 2 This is a real-time monitoring and evaluation diagram of an embodiment of the method for early detection of well leakage based on downhole engineering parameter measurement of the present invention. DETAILED DESCRIPTION

[0080] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0081] Refer to the instruction manual Figures 1 to 2 The embodiment of the present invention provides a method for early detection of well leakage based on downhole engineering parameter measurement, and the specific steps include:

[0082] Step 1: Data collection, preliminary determination of the depth range and lithology of leakage. Based on the well history data and comprehensive logging data, the depth range of leakage and the lithology developed in the strata within the depth range are preliminarily determined.

[0083] Step 2: Surface input data (injection displacement, return displacement, injection density, drilling fluid viscosity, dynamic plastic ratio, static shear force, dynamic shear force, six-speed viscometer reading, pump pressure, vertical pressure) are used to calculate and simulate the characteristic parameters when leakage occurs and during normal drilling, including the inner pipe pressure at the measuring point, annular pressure, internal and external pressure difference, and temperature.

[0084] In this step, the fundamental characteristic parameters of the leakage occurrence formula are the inner tube pressure, the annulus pressure and the pressure difference between the two, and the temperature is also a reference parameter.

[0085] The specific calculation method is as follows:

[0086] ①Inner pipe pressure during normal drilling

[0087] During normal drilling, the inner pipe pressure is calculated using a mature hydraulic model to obtain the pressure inside the drill string at the depth of the measuring point.

[0088] ② Annular pressure during normal drilling

[0089] During normal drilling, the annular pressure is calculated using a mature hydraulic model to obtain the pressure of the drill string annulus at the depth of the measuring point.

[0090] ③ Pressure difference between inside and outside during normal drilling

[0091] The internal and external pressure difference during normal drilling refers to the difference between the inner pipe pressure and the annulus pressure during normal drilling.

[0092] ④Inner pipe pressure during well leakage

[0093] The inner tube pressure during well leakage is calculated based on the wellbore pressure calculation model during well leakage, and the pressure inside the drill string at the depth of the measuring point is obtained.

[0094] ⑤ Annular pressure during well leakage

[0095] The annular pressure during well leakage is calculated based on the wellbore pressure calculation model during well leakage, and the pressure of the drill string annulus at the depth of the measuring point is obtained.

[0096] ⑥ Pressure difference between inside and outside when the well is leaking

[0097] The internal and external pressure difference during well leakage refers to the difference between the inner pipe pressure and the annulus pressure during well leakage.

[0098] On the basis of the calculation model of well leakage characteristic parameters, the characteristic parameter diagram when leakage occurs and the characteristic parameter diagram during normal drilling are simulated and calculated according to the ground input data; the simulation calculation includes the calculation of leakage velocity, the calculation of wellbore pressure when leakage occurs, and the calculation of internal and external pressure difference when leakage occurs.

[0099] Step 3: Obtain real-time characteristic parameters; use the downhole drilling data measured by the measurement while drilling system to input the software to form a real-time data monitoring chart.

[0100] Step 4: Draw a comparison chart of measurements and predictions based on the data obtained in steps 1 to 3 above, and perform omission detection, early warning and alarm on the results.

[0101] The specific method of identifying the leaking layer and analyzing the leakage mechanism by comparing the measured and predicted diagrams is to judge based on the predicted and calculated values ​​of the inner pipe and annular pressures and the internal and external pressure differences in the measured and predicted diagrams:

[0102] When P 环空测量 ≈P 环空模拟正常 , normal drilling;

[0103] When P 环空测量 <P 环空模拟正常 :

[0104] If ΔP 井下测量 ≈ΔP 井下模拟 , and the changing trend of the measured annular pressure monitoring diagram is consistent with the annular pressure diagram when the simulated well leakage occurs, and the downhole temperature changes suddenly, it can be considered that the well leakage occurs in the well.

[0105] In order to more clearly and in detail introduce the early detection method of well leakage based on downhole engineering parameter measurement provided by the embodiment of the present invention, it will be described in conjunction with specific embodiments below.

[0106] Analyze and calculate according to steps 1 to 5. Please refer to the attached Figure 1 , a certain block of Changqing Oilfield was processed for Well T, and the real-time monitoring and evaluation chart is shown in the attached Figure 2 .

[0107] The simulated values ​​of the inner tube pressure, annular pressure and internal and external pressure difference during normal drilling and well leakage in the figure are obtained according to the formula method given in steps one to three. It can be seen from the real-time monitoring and evaluation diagram of Well T that leakage began to occur at the depth section of 3102m. The judgment basis is: the measured inner tube pressure, annular pressure and pressure difference before 3102m are consistent with the inner tube pressure, annular pressure and pressure difference during normal drilling calculated based on the simulation of ground data, while the measured inner tube pressure and annular pressure after 3102m are significantly reduced, and the internal and external pressure difference remains basically unchanged, which generally meets the evaluation criteria for leakage, and is consistent with the inner tube pressure, annular pressure and pressure difference when well leakage occurs calculated based on the simulation of ground data. After drilling to 3108m, it was found that 0.5m3 was lost in 20 minutes, and the leakage rate was 1.5m3 / h. Multi-stage plugging materials were added to reduce the density of drilling fluid, and the leakage was effectively controlled and continued drilling. It can be verified that the analysis results of the method of the present invention are consistent with the actual situation, accurate and effective, and earlier than the surface mud tank liquid level monitoring, thereby providing a basis for the formulation of drilling construction plans and leak prevention and plugging plans.

[0108] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An early detection method for well leakage based on downhole engineering parameter measurement, characterized in that: include: Step 1: Data collection to preliminarily determine the depth range and lithology of the leakage; Based on the well history data and comprehensive logging data, the depth range of leakage and the lithology developed in the strata within this depth range are preliminarily delineated; Step 2: Establish a calculation model for the characteristic parameters of well leakage according to the flow characteristics when well leakage occurs; Based on the calculation model of the characteristic parameters of the well leakage, the characteristic parameter diagram when the leakage occurs and the characteristic parameter diagram when the drilling is normal are simulated and calculated according to the ground input data; the simulation calculation includes the calculation of the leakage velocity, the calculation of the wellbore pressure when the leakage occurs, and the calculation of the internal and external pressure difference when the leakage occurs; Step 3: Obtain real-time characteristic parameters; use the downhole drilling data measured by the drilling measurement system to input the software to form a real-time data monitoring chart; Step 4: Determine the leakage judgment criteria; draw a comparison chart of measurement and prediction parameters based on the data obtained in the above steps 1 to 3, and judge and warn the leakage through the results. The leakage velocity calculation, wellbore pressure calculation at the time of leakage, and internal and external pressure difference calculation at the time of leakage in step 2 include: ① Calculation of leakage velocity: The leakage rate is calculated by intersecting the annular pressure calculation equations above and below the leakage point, and the pressure calculation equation group above and below the leakage point is: Q 排量 =Q 漏失排量 +Q 漏点以上排量 （3） The leakage velocity is obtained through iterative calculation based on the above equation; ② Calculation of wellbore pressure during leakage: Inner pipe pressure: The following pressures are observed at the annular leak point: Pressure above the annulus leak point: ③ Calculation of internal and external pressure difference during leakage: ΔP 井下模拟 =P 内管模拟 -P 环空模拟 (11); The characteristic parameters when leakage occurs and the characteristic parameters during normal drilling calculated based on the simulated surface input data in step 2 include: injection displacement, return displacement, injection density, drilling fluid viscosity, dynamic plasticity ratio, static shear force, dynamic shear force, six-speed viscometer reading, pump pressure, and vertical pressure; the leakage judgment criteria in step 4 specifically include: According to the predicted and calculated values ​​of the inner tube and annulus pressures and the internal and external pressure difference in the measurement and prediction comparison diagram, it can be judged that: When P 环空测量 ≈P 环空模拟正常 , normal drilling; When P 环空测量 <P 环空模拟正常 : If ΔP 井下测量 ≈ΔP 井下模拟 , and the change trend of the measured annular pressure monitoring diagram is consistent with the annular pressure diagram when the simulated well leakage occurs, and the downhole temperature changes suddenly, it can be considered that the well leakage occurs in the well; Where: P 环空漏点 is the annular pressure at the leak point, MPa; P 地层压力 is the formation pressure at the leak point, MPa; It is the sum of the annular friction above the leak point, MPa; v 排量 is the annular velocity below the leak, m / s; v 漏失速度 is the leakage velocity at the leak point, m / s; v 漏点以上环空速度 is the annular velocity above the leak point, m / s; ρ is the drilling fluid density, kg / m3; H 漏深 is the well depth of the leak point, m; g is the acceleration due to gravity, m / s2; Q 排量 is the surface input displacement, m3 / s; Q 漏失排量 is the flow rate leaking into the formation, m3 / s; Q 漏点以上排量 is the annular flow rate above the leak point, m3 / s; S 环空 is the annulus area, m2; S 漏点 is the leak area, m2; ΔP 内管 is the inner tube pressure loss, MPa; ΔP 环空漏点以下 is the annular pressure loss below the leak point, MPa; ΔP 环空漏点以上 is the annular pressure loss above the leak point, MPa; f wl is the friction coefficient, dimensionless; D 内管 is the inner tube diameter, m; ΔL is the tube length, m; n' is the flow pattern index, dimensionless; Re g is the Reynolds number, dimensionless; f wl is the friction coefficient in turbulent flow; ΔP 井下模拟 is the simulated internal and external pressure difference, MPa; P 内管模拟 is the simulated calculated inner tube pressure, MPa; P 环空模拟 is the simulated calculated outer pipe pressure, MPa.

2. The method for early detection of well leakage based on downhole engineering parameter measurement according to claim 1, characterized in that: The characteristic parameter diagram when leakage occurs and the characteristic parameter diagram during normal drilling in step 2 include: standing pressure, simulated annular space pressure, simulated standing pressure, and simulated internal and external pressure difference.

3. The method for early detection of well leakage based on downhole engineering parameter measurement according to claim 1, characterized in that: The real-time data monitoring diagram in step three includes inner tube pressure, annulus pressure, internal and external pressure difference, and annulus temperature.

4. The method for early detection of well leakage by measuring downhole engineering parameters according to claim 1, characterized in that: The step three also includes calculating the internal and external pressure difference when leakage occurs, and the calculation formula is as follows: ΔP 井下测量 =P 内管测量 -P 环空测量 （12） 。

Images