Early detection method for drill string leakage based on downhole engineering parameter measurement

Abstract

This invention provides an early detection method for drill string leakage based on downhole engineering parameter measurement. It can promptly detect early leakage by analyzing changes in downhole engineering parameters measured during drilling, particularly changes in characteristic parameters of the leakage, allowing for timely intervention, saving drilling time, and preventing further complications that could escalate into drill string accidents. The specific steps include: (i) establishing a calculation model for characteristic parameters of the leakage based on the flow characteristics during leakage; (ii) calculating and simulating the parameter change roadmap during leakage and normal drilling based on the calculation model and ground-based input data; (iii) inputting the measured values ​​from the downhole engineering parameter measurement-while-drilling system into the software to generate a real-time data monitoring chart; and (iv) compiling and drawing a measurement and prediction comparison chart based on the data obtained in steps (i) to (iii), and using the results to identify, warn, and alert on the leakage.

Description

Technical Field

[0001] This invention relates to a method for detecting drill string leakage in the field of drilling exploration, and more particularly to an early detection method for drill string leakage based on downhole engineering parameter measurements. Background Technology

[0002] Drill string leakage, also known as drill string puncture, occurs during drilling operations when poor sealing at the drill string connection or joint, or damage to the drill string material itself, allows drilling fluid to penetrate through this weak point. It is one of the most common and complex drilling problems. Drill string leakage poses significant risks: drilling fluid bypasses the drill bit and downhole accelerators, entering the annulus directly, reducing drill bit hydraulic and motor power, and impacting cutterhead carrying efficiency. Furthermore, the surface manifestation of drill string leakage is similar to other downhole problems, hindering assessment of the working conditions. Additionally, the high flow rates and pressures downhole mean that untimely intervention can easily lead to drill string breakage, resulting in substantial material losses, delays in drilling, and extended drilling cycles. Therefore, early identification of drill string leakage is of paramount importance.

[0003] Currently, the most widely used leakage identification technologies mainly include the following methods: The first is the observation and experience method, mainly applied at the drilling site. The following six phenomena are considered: 1. Pump pressure drop. 2. Slower drilling speed. 3. Increased rotary table load. 4. More rock cuttings collapsing and falling off the vibrating screen than drill cuttings. 5. Increased friction during lifting and lowering. 6. Increased pump pressure but not increase, instead decreasing. If three or more of these occur, it can be identified as drill string leakage. The second is the integrated logging method. Domestic and international petroleum scientists have used integrated logging equipment to track and monitor drilling safety during well construction, as well as to predict and forecast downhole faults (including well kick, well leakage, drill string leakage, water nozzle loss, water plugging, drill string slippage, stuck drill string, drilling obstruction, oil, gas and water intrusion, and drill string loss), playing a crucial role in ensuring safe drilling. However, integrated logging technology is relatively outdated, and relying solely on surface data is easily affected by changes in pump pressure, displacement, and drilling fluid chemical additions. Summary of the Invention

[0004] The purpose of this invention is to provide an early detection method for drill string leakage based on downhole engineering parameter measurements. Addressing the shortcomings of existing technologies, this invention leverages the real-time measurement capabilities of downhole engineering parameter measurement systems to effectively acquire downhole tubing pressure, annular pressure, and annular temperature. It then compares and analyzes simulated values ​​calculated based on surface injection parameters to identify drill string leakage. The early detection method provided by this invention overcomes the deficiencies of existing technologies, enabling rapid identification of drill string leakage. It can promptly detect early leakage based on changes in downhole engineering parameters measured during drilling, particularly changes in characteristic parameters of drill string leakage, allowing for timely intervention, saving drilling time, and preventing further complications that could escalate into drill string accidents.

[0005] To solve the above technical problems, the present invention is achieved by adopting the following technical solution:

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

[0007] (i) Based on the flow characteristics when drill string leakage occurs, establish a wellbore parameter calculation model, especially a calculation model for drill string leakage characteristic parameters, to provide a theoretical basis for wellbore parameter calculation;

[0008] (ii) Based on the calculation model of the drill string leakage characteristic parameters, calculate and simulate the parameter change roadmap when drill string leakage occurs and during normal drilling based on the ground input data;

[0009] (iii) Use the measured values ​​of the downhole engineering parameters measurement while drilling system to input the software to form a real-time data monitoring chart;

[0010] (iv) Based on the data obtained in steps (i) to (iii) above, a comparison chart of measurement and prediction is drawn. The results are used to identify and warn of drill bit leakage.

[0011] Preferably, the specific explanation and calculation process in step (i) are as follows:

[0012] ① Calculation of drill string leakage rate

[0013] The drill string leakage velocity is calculated by intersecting the equations for the annular pressure above and below the leakage point. The equation set for the pressure above and below the leakage point is as follows:

[0014]

[0015]

[0016] In the formula It is the sum of the inner tube friction below the leak point + drill bit pressure drop + annular friction.

[0017] Q 排量 =Q 漏排量 +Q 漏点以下排量 (3)

[0018]

[0019]

[0020]

[0021] The leakage rate is obtained through iterative calculation based on the above equations.

[0022] ② Wellbore pressure calculation

[0023] Inner tube pressure

[0024]

[0025] Pressure below annular leak point

[0026]

[0027] Pressure above annular leak point

[0028]

[0029]

[0030] In the formula f wl This section describes the method for calculating the friction coefficient in turbulent flow. For calculations in laminar and transitional flow, refer to relevant monographs on non-Newtonian fluid mechanics.

[0031] ③ Calculation of internal and external pressure difference

[0032] ΔP 井下模拟 =P 内管模拟 -P 环空模拟 (11)

[0033] Preferably, the parameters calculated in step (ii) based on the ground input data during the simulation calculation of the drill string leakage and normal drilling include injection flow rate, return flow rate, injection density, drilling fluid viscosity, dynamic-plastic ratio, static shear force, dynamic shear force, six-speed viscometer reading, pump pressure, and vertical pressure.

[0034] Preferably, the simulated and ground parameter change roadmap monitored in step (ii) includes vertical pressure, simulated annular pressure, simulated vertical pressure, and simulated internal and external pressure difference.

[0035] Preferably, in step (iii), the input software forms a real-time data monitoring version including inner tube pressure, annular pressure, internal and external pressure difference, and annular temperature.

[0036] Preferably, the formula for calculating the internal and external pressure difference in step (iii) is as follows:

[0037] ΔP 井下测量 =P 内管测量 -P 环空测量 (12)

[0038] Preferably, in step (iv), the method for identifying leaks by comparing the measured and predicted values, and analyzing drill string leakage, is as follows: The leaks are determined based on the predicted and calculated values ​​of the inner tube and annular pressures, as well as the internal and external pressure differences, as shown in the comparison chart.

[0039] When P 环空测量 ≈P 环空模拟正常 Normal drilling progress;

[0040] When P 环空测量 <P 环空模拟正常 :

[0041] If ΔP 井下测量 ≈ΔP 井下模拟 If the measured annular pressure monitoring chart shows a consistent trend with the annular pressure chart when the simulated drill string leakage occurs, and the downhole temperature changes abruptly, then it can be considered that a drill string leakage has occurred downhole.

[0042] Compared with existing technologies, the beneficial effects of this invention are: It leverages the real-time measurement capabilities of downhole engineering parameter measurement systems to effectively acquire downhole tubing pressure, annular pressure, and annular temperature, and combines this with simulated values ​​calculated based on surface injection parameters for comparative analysis and identification of drill string leakage. This method can quickly identify drill string leakage, providing a basis for the formulation of drilling operation plans and subsequent construction measures. It provides an early detection method for drill string leakage based on downhole engineering parameter measurement, providing a basis for addressing drill string leakage as early as possible. Attached Figure Description

[0043] Figure 1 The flowchart for identifying drill bit leaks in this invention.

[0044] Figure 2 This is a real-time monitoring and evaluation graph from an embodiment of the present invention. Detailed Implementation

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Refer to the instruction manual appendix Figure 1 and 2 An early detection method for drill string leakage based on downhole engineering parameter measurement, the specific steps of which include:

[0047] Step (1): Input data from the ground (injection volume, return volume, injection density, drilling fluid viscosity, dynamic plastic ratio, static shear force, dynamic shear force, six-speed viscometer reading, pump pressure, vertical pressure) to calculate and simulate characteristic parameters during drill string leakage and normal drilling, including the inner tube pressure at the measuring point, annular pressure, internal and external pressure difference, and temperature.

[0048] In this step, the fundamental characteristic parameters when drill string leakage occurs are the inner tube pressure, the annular pressure, and the pressure difference between the two, while temperature is also a reference parameter.

[0049] The specific calculation method is as follows:

[0050] ①Inner tube pressure during normal drilling

[0051] During normal drilling, the pressure inside the drill string at the measurement point depth is calculated using a mature hydraulic model.

[0052] ② Annular pressure during normal drilling

[0053] During normal drilling, the annular pressure is calculated using a mature hydraulic model to obtain the pressure in the drill string annulus at the depth of the measurement point.

[0054] ③ Pressure difference between inside and outside during normal drilling

[0055] During normal drilling, the pressure difference between the inside and outside refers to the difference between the pressure in the inner tube and the pressure in the annulus during normal drilling.

[0056] ④ Inner tube pressure when the drill bit leaks

[0057] The pressure inside the drill string when the drill string leaks is calculated based on the wellbore pressure calculation model when the drill string leaks, which is the pressure inside the drill string at the depth of the measurement point.

[0058] ⑤ Annular pressure during drill string leakage

[0059] The annular pressure during drill string leakage is calculated based on the wellbore pressure calculation model during drill string leakage, which yields the pressure in the drill string annulus at the depth of the measurement point.

[0060] ⑥ Pressure difference between inside and outside when the drill bit leaks

[0061] The pressure difference between the inside and outside of the drill string during leakage refers to the difference between the pressure in the inner tube and the pressure in the annulus when the drill string leaks.

[0062] Step (2): Calculate the parameter results when the drill string leaks and during normal drilling by inputting real-time ground monitoring data, and then draw a real-time characteristic parameter simulation change route map.

[0063] Step (3): Using the measurement values ​​of the downhole engineering parameters measurement while drilling system, a real-time downhole characteristic monitoring map is generated.

[0064] Step (4): Based on the data obtained in steps (1) to (3), compile and draw a comparison chart of measurement and prediction, and use the results to identify and alarm for drill bit leakage.

[0065] The specific method for identifying drill string leakage and analyzing its mechanism through a comparison of measurement and prediction charts is as follows: The judgment is made based on the predicted and calculated values ​​of the inner tube and annulus pressures, as well as the internal and external pressure differences, as shown in the comparison charts.

[0066] When P 环空测量 ≈P 环空模拟正常 Normal drilling progress;

[0067] When P 环空测量<P 环空模拟正常 :

[0068] If ΔP 井下测量 ≈ΔP 井下模拟 If the measured annular pressure monitoring chart shows a consistent trend with the annular pressure chart when the simulated drill string leakage occurs, and the downhole temperature changes abruptly, then it can be considered that a drill string leakage has occurred downhole.

[0069] To provide a clearer and more detailed description of the early detection method for drill string leakage based on downhole engineering parameter measurement provided in this invention, the following will be described in conjunction with specific embodiments.

[0070] Perform the analysis and calculations according to steps (I) to (IV), referring to the attached flowchart. Figure 1 The following is a sample chart showing the processing of a well in a certain block of the Changqing Oilfield, with real-time monitoring and evaluation. Figure 2 .

[0071] The simulated values ​​of inner tube pressure, annular pressure, and internal-external pressure difference during normal drilling and when the drill string leaks are shown in the figure. These values ​​were obtained using the formulas and methods given in steps (I)-(III). According to the real-time monitoring and evaluation chart of well T, drill string leakage began at 3252m. The basis for this judgment is that the measured inner tube pressure, annular pressure, and pressure difference before 3252m were consistent with the inner tube pressure, annular pressure, and pressure difference calculated based on surface data during normal drilling. However, after 3252m, the measured inner tube pressure and annular pressure decreased significantly, and the internal-external pressure difference also decreased significantly. Overall, this met the evaluation criteria for drill string leakage and was consistent with the inner tube pressure, annular pressure, and pressure difference calculated based on surface data when the leakage occurred. Later, at 3306m, a leak was discovered at the drill pipe joint 241m from the bottom of the well during a trip to check. This verifies that the analytical results of the method of the present invention are consistent with the actual situation, accurate and effective, and earlier than the monitoring of the surface logging system, thus providing a basis for the formulation of drilling construction plans and subsequent construction measures.

Claims

1. A method for early detection of drill string leakage based on downhole engineering parameter measurement, characterized in that, Includes the following steps: (i) Based on the flow characteristics when drill string leakage occurs, a wellbore parameter calculation model is established to provide a theoretical basis for wellbore parameter calculation; (ii) Based on the calculation model of the characteristic parameters of drill string leakage, the parameters during drill string leakage and normal drilling are simulated and calculated according to the ground input data, and the parameter change roadmap during drill string leakage and normal drilling is formed. (iii) Use the measured values ​​of the downhole engineering parameter measurement while drilling system to generate real-time monitoring data graphs; (iv) Based on the data obtained in steps (i) to (iii) above, compile and draw a comparison chart of measurement and prediction, and use the results to identify and warn of drill bit leakage; The parameters mentioned in step (ii) when drill bit leakage occurs and during normal drilling include vertical pressure, simulated annular pressure, simulated vertical pressure, and simulated internal and external pressure difference; The real-time monitoring data graphs mentioned in step (iii) include inner tube pressure, annular pressure, internal and external pressure difference, and annular temperature; The ground input data mentioned in step (II) includes 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.

2. The method for early detection of drill string leakage based on downhole engineering parameter measurement according to claim 1, characterized in that, Step (i) includes: ① Calculation of drill string leakage rate The drill string leakage velocity is calculated by intersecting the equations for the annular pressure above and below the leakage point. The equation set for the pressure above and below the leakage point is as follows: （1）； （2）； In the formula It is the sum of the inner tube friction below the leak point, the drill bit pressure drop, and the annular friction. （3）； （4）； （5）； （6）； The leakage rate is obtained through iterative calculation based on the above equations; ② Wellbore pressure calculation Inner tube pressure （7）； Pressure below annular leak point （8）； Pressure above annular leak point （9）； （10）； In the formula, fwl is the friction coefficient during turbulent flow; ③ Calculation of internal and external pressure difference （11）。 3. The method for early detection of drill string leakage based on downhole engineering parameter measurement according to claim 2, characterized in that, The formula for calculating the internal and external pressure difference in step (iii) is as follows: （12）； In the formula, The internal and external pressure difference For the internal pipe pressure, Annular pressure.

4. The method for early detection of drill string leakage based on downhole engineering parameter measurement according to claim 3, characterized in that, The specific method for judging and issuing early warnings and alarms regarding drill string leakage in step (four) is to judge based on the predicted and calculated values ​​of the inner tube and annulus pressures and the internal and external pressure differences in the measurement and prediction comparison chart: when Normal drilling progress; when : like If the measured annular pressure monitoring chart shows a consistent trend with the annular pressure chart when the simulated drill string leakage occurs, and the downhole temperature changes abruptly, then it can be concluded that a drill string leakage has occurred downhole.

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