Formation pressure monitoring system based on DC index

Abstract

The invention relates to the technical field of petroleum drilling ground testing, in particular to a formation pressure monitoring system based on a DC index. Comprising the steps that a main control unit draws a target well formation pressure monitoring related curve according to formation pressure monitoring related parameters detected by a parameter detection unit, and the formation pressure monitoring related parameters at least comprise real-time pumping pressure, real-time drilling fluid density and real-time drilling pressure; the formation pressure monitoring related curve at least comprises a pump pressure change curve, a drilling fluid density change curve and a bit pressure change curve; and the main control unit determines the DC index of the target well according to the formation pressure monitoring related parameters, draws a DC index change curve and monitors the formation pressure of the target well according to the formation pressure monitoring related curve and the DC index change curve. The problems that when formation pressure monitoring is conducted in the prior art, formation pressure cannot be obtained in time, consumed time is long, pressure obtaining is prone to failing, abnormities in the drilling process cannot be found in time, and the drilling efficiency is affected are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil drilling ground testing, and particularly relates to a formation pressure monitoring system based on DC index. BACKGROUND

[0002] When oilfield development enters the double super high late stage, well pattern density will be larger and larger, and multiple well patterns exist in each block. In order to ensure stable production of the oilfield, a considerable number of adjustment wells are drilled in the old area every year. When drilling in the old area, the formation pressure needs to be monitored in real time during actual drilling. In the past, when monitoring the formation pressure in real time, the first method is to measure the pressure of drilling fluid inside and outside the drilling tool through a bottom hole drilling fluid pressure measuring tool. In the case of constant density, the change of the bottom hole pressure can be quickly determined. The disadvantage of this method is that the size of the formation pressure cannot be determined, and the data cannot be uploaded in real time. The data is stored in the main control of the tool, and the data is read after the wellhead is out. Only the next well can be used for reference, and the abnormal pressure of the well cannot be accurately and timely found. The second method is to use a formation pressure while drilling tool to obtain the formation pressure at any time during drilling. This method can upload real-time data to the ground. The disadvantage is that the pressure needs to be measured for more than 30 minutes when the drilling tool is stationary, which affects the drilling speed of the drilling team. In addition, the lithology of the formation is difficult to determine, and the pressure is easy to obtain failure. SUMMARY

[0003] The present application provides a formation pressure monitoring system based on DC index to solve the problem that the formation pressure cannot be obtained in time, the time is long, the pressure is easy to obtain failure, and the abnormality in the drilling process cannot be found in time, which affects the drilling efficiency.

[0004] According to one aspect of the present application, a formation pressure monitoring system based on DC index is provided, comprising: a parameter detection unit and a main control unit;

[0005] The main control unit is used to draw a target well formation pressure monitoring related curve according to the formation pressure monitoring related parameters detected by the parameter detection unit, wherein the formation pressure monitoring related parameters at least include: real-time pump pressure, real-time drilling fluid density and real-time drilling pressure, and the formation pressure monitoring related curve at least includes: pump pressure change curve, drilling fluid density change curve and drilling pressure change curve;

[0006] The main control unit is used to determine the DC index of the target well according to the formation pressure monitoring related parameters, and draw a DC index change curve;

[0007] The main control unit monitors the formation pressure of the target well according to the formation pressure monitoring related curve and the DC index change curve.

[0008] Preferably, the parameter detection unit comprises a pump pressure sensor and a pump pressure first wireless transmission module.

[0009] The pump pressure sensor is connected to the main control unit through the first wireless transmission module.

[0010] The pump pressure sensor is installed in the target well mud pump set, and is used to detect the real-time pump pressure inside the mud pump set and send it to the main control unit through the first wireless transmission module.

[0011] Preferably, the parameter detection unit further comprises a drilling fluid density sensor and a second wireless transmission module.

[0012] The drilling fluid density sensor is connected to the main control unit through the second wireless transmission module.

[0013] The drilling fluid density sensor is installed inside the target well mud tank, and is used to detect the real-time drilling fluid density inside the mud tank and send it to the main control unit through the second wireless transmission module.

[0014] Preferably, the parameter detection unit further comprises a hanging weight sensor and a third wireless transmission module.

[0015] The hanging weight sensor is connected to the main control unit through the third wireless transmission module.

[0016] The hanging weight sensor is installed on the drilling rig, and is used to detect the weight of the drilling tool in the suspended state and the weight of the drilling tool while drilling, and send it to the main control unit through the second wireless transmission module.

[0017] The main control unit determines the real-time drilling pressure according to the weight of the drilling tool in the suspended state and the weight of the drilling tool while drilling.

[0018] Preferably, the method for determining the DC index of the target well according to the formation pressure monitoring related parameters comprises:

[0019] Obtaining the target well rotating speed, mechanical rotating speed, drill bit diameter and normal formation pressure density;

[0020] According to the rotating speed, mechanical rotating speed, drill bit diameter and normal formation pressure density, combined with the drilling fluid density and the drilling pressure, the DC index of the target well is determined.

[0021] Preferably, the method for determining the DC index of the target well according to the rotating speed, mechanical rotating speed, drill bit diameter and normal formation pressure density, combined with the drilling fluid density and the drilling pressure, comprises:

[0022] Using formula (1) to determine the DC index;

[0023]

[0024] wherein: p is the drilling fluid density, g / cm 3 ; R is the rate of penetration, m / h; D is the bit diameter, mm; W is the weight on bit, t; V is the rotary table or top drive speed, r / min; Gn is the normal formation pressure density, g / cm 3 .

[0025] Preferably, the parameter detection unit further comprises: a rotary table speed sensor and a fourth wireless transmission module.

[0026] A rotary table speed sensor is installed on the wellhead platform of the target well, and the rotary table speed sensor is used to detect the real-time rotary table speed of the target well and send it to the master control unit through the fourth wireless transmission module.

[0027] Preferably, the formation pressure monitoring related parameters further comprise: real-time drilling fluid temperature.

[0028] The formation pressure monitoring related curves further comprise: a drilling fluid temperature change curve.

[0029] The parameter detection unit further comprises: a drilling fluid temperature sensor and a fifth wireless transmission module.

[0030] The drilling fluid temperature sensor is installed in.

[0031] Preferably, the method for the master control unit to monitor the formation pressure of the target well according to the pump pressure change curve, the drilling fluid density change curve, the weight on bit change curve and the DC index change curve comprises:

[0032] The master control unit determines whether there is an abnormal curve in all the formation pressure monitoring related curves and the DC index change curve, and if so, the master control unit performs a first level alarm prompt.

[0033] The master control unit determines whether there are two abnormal curves in all the formation pressure monitoring related curves and the DC index change curve, and if so, the master control unit performs a second level alarm prompt, and when the second level alarm prompt appears, the operator stops the well for inspection.

[0034] The master control unit determines whether there are three or more abnormal curves in all the formation pressure monitoring related curves and the DC index change curve, and if so, the master control unit performs a third level alarm prompt, and when the third level alarm prompt appears, the operator performs drilling fluid density increasing or decreasing operation.

[0035] Preferably, the abnormal curve is:

[0036] If the curve rises or falls by a value exceeding its corresponding predetermined change value within a predetermined time range, the curve is an abnormal curve.

[0037] The present application has at least the following beneficial effects:

[0038] The present application provides a formation pressure monitoring system based on DC index, detects various parameters related to formation pressure monitoring during drilling through the parameter detection unit, and draws various parameter change curves through the main control unit, and combines the DC index curve to monitor the formation pressure of the target well in real time, so that abnormal pressure can be found in time, and different formation pressure changes can be adjusted accordingly, improving drilling efficiency and safety. BRIEF DESCRIPTION OF DRAWINGS

[0039] The drawings incorporated into the specification and forming part thereof, show embodiments consistent with the present application, and together with the specification serve to explain the technical solutions of the present application.

[0040] Figure 1 A flowchart of a formation pressure monitoring system based on DC index according to an embodiment of the present application is shown;

[0041] Figure 2 A structural diagram of a parameter detection unit according to an embodiment of the present application is shown;

[0042] Figure 3 An installation diagram of a load sensor according to an embodiment of the present application is shown;

[0043] Figure 4 A structural diagram of a drilling fluid density sensor according to an embodiment of the present application is shown;

[0044] Figure 5 A structural diagram of a wireless receiving module according to an embodiment of the present application is shown.

[0045] In the figure, 1 - mud pump set, 2 - first wireless transmitting module, 3 - pump pressure sensor, 4 - inlet pipeline, 5 - second wireless transmitting module, 6 - mud tank, 7 - drilling fluid density sensor, 8 - drilling fluid temperature sensor, 10 - drilling fluid pipeline, 11 - drilling platform, 12 - wellhead, 13 - rotary table speed sensor, 14 - main control unit, 15 - wireless receiving module, 16 - load sensor, 17 - derrick. DETAILED DESCRIPTION

[0046] Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in the drawings represent functionally identical or similar elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0047] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0048] The term "and / or", used herein only to describe the connection relationship of associated objects, means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the term "at least one" herein means any one of the plurality or any combination of at least two of the plurality, for example, including at least one of A, B and C can mean including any one or more elements selected from the set consisting of A, B and C.

[0049] In addition, in order to better illustrate the present application, a large number of specific details are given in the specific embodiments below. Those skilled in the art should understand that without certain specific details, the present application can also be implemented. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present application.

[0050] Figure 1 A flowchart of a formation pressure monitoring system based on DC index according to an embodiment of the present application is shown; Figure 2 A structural diagram of a parameter detection unit according to an embodiment of the present application is shown; Figure 3 An installation diagram of a load sensor according to an embodiment of the present application is shown; Figure 4 A structural diagram of a drilling fluid density sensor according to an embodiment of the present application is shown; Figure 5 A structural diagram of a wireless receiving module according to an embodiment of the present application is shown. As Figures 1-5 A formation pressure monitoring system based on DC index, as shown, comprises a parameter detection unit and a main control unit; the main control unit is used to draw a target well formation pressure monitoring related curve according to the formation pressure monitoring related parameters detected by the parameter detection unit, wherein the formation pressure monitoring related parameters at least include real-time pump pressure, real-time drilling fluid density and real-time drilling pressure, and the formation pressure monitoring related curve at least includes pump pressure change curve, drilling fluid density change curve and drilling pressure change curve; the main control unit is used to determine the DC index of the target well according to the formation pressure monitoring related parameters, and draw a DC index change curve; the main control unit monitors the formation pressure of the target well according to the formation pressure monitoring related curve and the DC index change curve.

[0051] In the embodiments of the present application and Figure 2In the drilling process, the mud tank 6 filled with drilling fluid is connected to the mud pump set 1 through the inlet pipeline 4, and the mud pump set 1 is connected to the wellhead 12 on the drilling platform 11 through the drilling fluid pipeline 10.

[0052] The parameter detection unit detects the real-time pump pressure in the drilling process of the target well, the real-time drilling fluid density in the mud tank 6, and the real-time drilling pressure, and transmits the detected parameter values to the main control unit 14 in real time. After receiving the real-time drilling pressure, the main control unit draws a curve of the real-time drilling pressure changing with the depth, that is, a pump pressure change curve; after receiving the real-time drilling fluid density, the main control unit draws a curve of the drilling fluid changing with the depth, that is, a drilling fluid density change curve; and after receiving the real-time drilling pressure, the main control unit draws a curve of the drilling pressure changing with the depth, that is, a drilling pressure change curve.

[0053] The main control unit calculates the real-time DC index of the target well according to the detected parameters, and draws a real-time DC index change curve.

[0054] The main control unit monitors the formation pressure in the drilling process according to the pump pressure change curve, the drilling fluid density change curve, the drilling pressure change curve, and the DC index change curve, and controls the alarm unit to alarm when an abnormal situation is judged in the curve.

[0055] In the present application, the parameter detection unit comprises a pump pressure sensor and a first wireless transmission module; the pump pressure sensor is connected to the main control unit through the first wireless transmission module; the pump pressure sensor is installed in the mud pump set of the target well, and is used to detect the real-time pump pressure in the mud pump set and transmit the real-time pump pressure to the main control unit through the first wireless transmission module.

[0056] In the embodiment of the present application, the pump pressure sensor 3 is connected to the lower part of the mechanical pressure gauge in the mud pump set through a tee joint, and is located between the pump pressure gauge (mechanical pressure gauge) and the mud pump; the pump pressure sensor is connected to the main control unit; in use, the main control unit controls the pump pressure sensor to start and detect the real-time pump pressure of the mud pump.

[0057] The main control unit is provided with a wireless receiving module 15; when the pump pressure sensor detects the real-time pump pressure, the real-time pump pressure is transmitted to the wireless receiving module of the main control unit through the first wireless transmission module 2; and the main control unit draws a pump pressure change curve according to the real-time pump pressure.

[0058] In the process of injecting drilling fluid, the pump pressure will not change greatly under normal circumstances, but when the formation pressure suddenly rises or falls, the drilling fluid injection pressure will rise or fall under the condition that the set displacement is unchanged, and then the pump pressure will suddenly rise or fall; therefore, by setting the pump pressure sensor to monitor the pump pressure of the mud pump in real time and drawing the change curve of the pump pressure through the main control unit, the change of the formation pressure can be analyzed, so that the drilling parameters can be adjusted more accurately and timely.

[0059] In the application, the parameter detection unit further comprises a drilling fluid density sensor and a second wireless transmission module; the drilling fluid density sensor is connected to the main control unit through the second wireless transmission module; the drilling fluid density sensor is installed inside the target well mud tank, and is used to detect the real-time drilling fluid density inside the mud tank and send it to the main control unit through the second wireless transmission module.

[0060] In the embodiment of the application, the drilling fluid density sensor 7 is installed on the mud tank, the probe is inserted 50 cm below the drilling fluid level, and the drilling fluid density sensor is connected to the main control unit; in use, the main control unit controls the drilling fluid density sensor to start and detect the real-time density of the drilling fluid in the mud tank.

[0061] When the drilling fluid density sensor detects the real-time drilling fluid density, it is wirelessly transmitted to the wireless receiving module of the main control unit through the second wireless transmission module 5, and the main control unit draws a drilling fluid density change curve according to the real-time drilling fluid density.

[0062] In the drilling process, the density of the mud (drilling fluid) generally does not change, but when the formation pressure suddenly rises, it may cause the fluid in the formation to enter the annulus, return to the wellhead, enter the mud tank through the overhead pipeline, and thus dilute the drilling fluid inside and cause the density to suddenly decrease; therefore, by setting the drilling fluid density sensor to monitor the drilling fluid density in the mud tank in real time and drawing a change curve thereof by the main control unit, the formation pressure change can be analyzed, so that the drilling parameters can be adjusted more accurately and timely.

[0063] In the application, the parameter detection unit further comprises a hook load sensor and a third wireless transmission module; the hook load sensor is connected to the main control unit through the third wireless transmission module; the hook load sensor is installed on the drilling rig, and is used to detect the weight of the drilling tool in the suspended state and the weight of the drilling tool during drilling, and send it to the main control unit through the second wireless transmission module; the main control unit determines the real-time drilling pressure according to the weight of the drilling tool in the suspended state and the weight of the drilling tool during drilling.

[0064] In the embodiment of the application, the hook load sensor 16 is installed at the dead rope of the drilling rig mast 17, and the hook load sensor is connected to the main control unit; in use, the main control unit controls the hook load sensor to start and detect the real-time weight of the drilling tool.

[0065] When the hook load sensor detects the real-time weight of the drilling tool, it is wirelessly transmitted to the wireless receiving module of the main control unit through the third wireless transmission module, and the main control unit determines the corresponding real-time drilling pressure according to the real-time weight of the drilling tool and draws a drilling pressure change curve.

[0066] Wherein, the weight of the whole drilling tool can be measured by using the hanging weight sensor, the real-time drilling tool weight contains two state values, one is the weight in the state of hanging drilling tool, and the other is the weight in the state of drilling; in the state of drilling, part of the weight of the whole drilling tool acts on the rock, and this part of the weight is called the drilling pressure, that is, the weight in the state of hanging drilling tool W1=weight in the state of drilling W2+drilling pressure W3; therefore, the method for the main control unit to determine the drilling pressure according to the weight of the drilling tool is: drilling pressure W3=weight in the state of hanging drilling tool W1-weight in the state of drilling W2.

[0067] In the drilling process, when the formation pressure suddenly rises, the formation fluid approaches the bottom end of the drilling tool upward, the density of the formation fluid is lower than that of the drilling fluid, and the resistance of the drill bit in the drilling process will decrease, thereby causing the drilling pressure to decrease; therefore, by setting the hanging weight sensor to monitor the weight of the drilling tool in real time and by the main control unit to calculate the drilling pressure and draw the change curve, the formation pressure change can be reflected.

[0068] In the application, the method for determining the target well DC index according to the formation pressure monitoring related parameters comprises: acquiring the target well rotary table rotating speed, mechanical rotating speed, drill bit diameter and normal formation pressure density; and determining the target well DC index according to the rotary table rotating speed, mechanical rotating speed, drill bit diameter and normal formation pressure density in combination with the drilling fluid density and the drilling pressure.

[0069] In the application, the method for determining the target well DC index according to the rotary table rotating speed, mechanical rotating speed, drill bit diameter and normal formation pressure density in combination with the drilling fluid density and the drilling pressure comprises:

[0070] The DC index dc is determined by using formula (1);

[0071]

[0072] In the formula, ρ is the drilling fluid density, g / cm 3 ; R is the mechanical drilling speed, m / h; D is the drill bit diameter, mm; W is the drilling pressure, t; V is the rotary table or top drive rotating speed, r / min; and Gn is the normal formation pressure density, g / cm 3 .

[0073] In the application, the parameter detection unit further comprises a rotary table rotating speed sensor and a fourth wireless transmission module; the rotary table rotating speed sensor is installed on the target well wellhead drilling platform, and is used to detect the real-time rotary table rotating speed of the target well and send the real-time rotary table rotating speed to the main control unit through the fourth wireless transmission module.

[0074] In the embodiment of the present application, the rotary table rotating speed sensor 13 is installed on the rotary table at the wellhead on the drilling platform, and the rotary table rotating speed sensor is connected to the master control unit; in use, the master control unit controls the rotary table rotating speed sensor to start, and detects the real-time rotary table rotating speed.

[0075] When the rotary table rotating speed sensor detects the real-time rotary table rotating speed, the real-time rotary table rotating speed is wirelessly transmitted to the wireless receiving module of the master control unit through the fourth wireless transmission module; the master control unit calculates the corresponding actual DC index according to the real-time rotary table rotating speed, in combination with the known mechanical rotating speed, drill bit diameter, drilling pressure and normal formation pressure density, and uses formula (1) to calculate the corresponding actual DC index, and draws a DC index change curve.

[0076] In the drilling process, when the formation pressure suddenly rises, the drilling fluid density, drilling pressure and rotary table rotating speed and other parameters will change, thereby causing the DC index to also change, and the DC index curve change can reflect the formation pressure change according to the comprehensive reflection of multiple parameters.

[0077] In the DC index change curve monitoring, whether the DC index is abnormal can be determined by comparison with the normal trend line; the normal trend line is a DC index-depth relationship curve constructed before drilling, which is calculated through logging data and is an important basis for pressure interpretation, and the calculation formula of the normal trend line is shown as formula (2).

[0078] D cn =A0*H+A1

[0079] In the formula, A0 is the slope; A1 is the intercept of the trend line; H is the vertical well depth, m; D cn is the DC index of the normal trend line.

[0080] In normal drilling, the trend of the DC index is roughly inclined to the right and down according to a certain K value, that is, it is relatively consistent with the normal trend line, at this time, the normal pressure change, and the normal drilling can be carried out; when sudden mutation to the left or to the right occurs, that is, lower than or higher than the normal trend line, at the same time, the drilling pressure is reduced, and the mechanical drilling speed is increased, which indicates that the abnormal high pressure formation has been entered, and vice versa, which indicates that the abnormal low pressure formation has been entered.

[0081] In the present application, the formation pressure monitoring related parameters further include: real-time drilling fluid temperature; the formation pressure monitoring related curve further includes: drilling fluid temperature change curve; the parameter detection unit further includes: drilling fluid temperature sensor and fifth wireless transmission module; the drilling fluid temperature sensor is installed on.

[0082] In the embodiment of the present application, the drilling fluid temperature sensor 8 is installed inside the mud tank, the probe is inserted 50 cm below the drilling fluid level, and the drilling fluid temperature sensor is connected to the main control unit; in use, the main control unit controls the drilling fluid temperature sensor to start, and detects the real-time temperature of the drilling fluid in the mud tank.

[0083] When the drilling fluid temperature sensor detects the real-time drilling fluid temperature, it is wirelessly transmitted to the wireless receiving module of the main control unit through the fifth wireless transmission module, and the main control unit draws a drilling fluid temperature change curve according to the real-time drilling fluid temperature.

[0084] In the drilling process, the temperature of the mud (drilling fluid) basically does not change much, but when the formation pressure suddenly rises, it may cause the underground fluid to return to the mud tank, and the underground fluid temperature is relatively high, thereby causing the internal drilling fluid temperature to suddenly rise; therefore, by setting the drilling fluid temperature sensor to monitor the drilling fluid temperature in the mud tank in real time and drawing its change curve through the main control unit, it can help to analyze the formation pressure change.

[0085] In the embodiment of the present application, the parameter detection unit includes: a pump pressure sensor, a first wireless transmission module, a drilling fluid density sensor, a second wireless transmission module, a load sensor, a third wireless transmission module, a rotary table speed sensor, a fourth wireless transmission module, a drilling fluid temperature sensor, and a fifth wireless transmission module. All the above sensors are based on full-well field wireless network transmission, and adopt the architecture of a wireless receiving module and multiple wireless transmission modules. Each sensor is not only responsible for collecting field data, but also has an independent processing chip built-in for processing collected data, directly obtaining the required engineering value according to the process requirements, similar to the DCS structure. The wireless transmission module outputs are all processed digital signals, which ensures the reliability of data transmission and reduces the computing load of the main station (main control unit). Each wireless transmission module is independent of each other and does not affect each other, each has an independent address, which can avoid interference caused by other devices around. The parameters collected by the sensor are transmitted to the corresponding wireless transmission module in 485 format through the data line, and the signal is converted into Zigbee format in the wireless transmission module through the conversion circuit, so as to realize stable transmission of data in the well site in a wireless manner.

[0086] The main control unit can be a computer, which is arranged in a well site instrument or a driller's room, and a special software embedded in the computer is a "brain" of the whole system, which is responsible for signal processing, correction and final user display of all original data, and manages operation of all terminals of the drilling instrument system, and all mathematical models are run in the computer. The main control unit also provides external data and operation interface. Since a well drilling often lasts for a long time, the monitoring of the DC index is performed at any time, and a large amount of data is accumulated, and a large amount of time is occupied by re-inputting all previous data each time, therefore, the main control unit can save data, and the internal program of the main control unit can call the stored data next time, and then input new data.

[0087] In the application, the method for monitoring formation pressure of a target well by the main control unit according to the pump pressure change curve, the drilling fluid density change curve, the drilling pressure change curve and the DC index change curve comprises the following steps: the main control unit determines whether there is an abnormal curve in all the formation pressure monitoring related curves and the DC index change curve, and if yes, the main control unit performs a first-level alarm; the main control unit determines whether there are two abnormal curves in all the formation pressure monitoring related curves and the DC index change curve, and if yes, the main control unit performs a second-level alarm, and when the second-level alarm occurs, an operator stops well drilling for inspection; the main control unit determines whether there are more than three abnormal curves in all the formation pressure monitoring related curves and the DC index change curve, and if yes, the main control unit performs a third-level alarm, and when the third-level alarm occurs, the operator performs drilling fluid density increasing or decreasing operation.

[0088] In the application, the abnormal curve is a curve whose rising or falling value exceeds a corresponding predetermined change value within a predetermined time range.

[0089] In the embodiment of the application, the main control unit processes the received real-time pump pressure, real-time drilling fluid density, real-time drilling pressure and / or real-time drilling fluid temperature value, filters out abnormal values, calculates corresponding DC values according to drilling pressure, drilling fluid density and rotary table speed and / or drilling fluid temperature, draws DC index change curve, pump pressure change curve, drilling fluid density change curve, drilling pressure change curve and / or drilling fluid temperature change curve, and displays the curves on a display screen, so that an operator can observe the change of each curve in real time.

[0090] Meanwhile, the master control unit automatically monitors the change of several curves, and judges whether the rising or falling amplitude of the several curves within a predetermined time range exceeds the predetermined change value corresponding to the curve. For example, the master control unit detects whether the change amplitude value (rising or falling value) of the DC index change curve within 60 seconds exceeds 3 MPa, and if yes, it means that the DC index curve is abnormal; the master control unit detects whether the change amplitude value (rising or falling value) of the pump pressure change curve within 60 seconds exceeds 1 MPa, and if yes, it means that the pump pressure change curve is abnormal; the master control unit detects whether the change amplitude value (falling value) of the drilling fluid density change curve within 60 seconds exceeds 0.2 g / cm 3 , and if yes, it means that the drilling fluid density change curve is abnormal; the master control unit detects whether the change amplitude value (falling value) of the drilling pressure change curve within 60 seconds exceeds 1 t, and if yes, it means that the drilling pressure change curve is abnormal; and / or, the master control unit detects whether the change amplitude value (rising value) of the drilling fluid temperature change curve within 60 seconds exceeds 3℃, and if yes, it means that the pump pressure change curve is abnormal.

[0091] When the master control unit monitors that there is an abnormal curve in all curves, such as the DC index change curve is abnormal, a first-level alarm prompt will be sent out, such as a pop-up prompt on the display screen, prompting the operator to be vigilant. When the formation pressure changes greatly, more than one curve in the curve will be abnormal, and when only one curve is abnormal, it may be that the sensor detects an error or the data transmission is abnormal, etc. At this time, the formation pressure can be continuously and closely monitored, and temporarily no adjustment is made, and the remaining curves are continuously monitored for abnormalities.

[0092] When the master control unit monitors that there are two abnormal curves in all curves, such as the DC index and pump pressure change curves suddenly rise or fall, a second-level alarm prompt will be sent out, such as a pop-up prompt on the display screen, and a sound alarm will be sounded at the same time. At this time, the probability of abnormal formation pressure is relatively large, and the operator needs to stop the well for inspection to further confirm whether it enters an abnormal high-pressure or low-pressure formation, and make adjustments according to the specific confirmation result.

[0093] When the master control unit monitors that there are three or more abnormal curves in all curves, such as the DC index, pump pressure and drilling fluid density change curves are abnormal, a third-level alarm prompt will be sent out, such as a pop-up prompt on the display screen, and a sound and light alarm will be controlled at the same time, and a stop drilling instruction will be sent out and / or an alarm prompt will be sent to each terminal such as the driller and relevant personnel. At this time, it can be basically confirmed that the formation pressure is abnormal, and the operator adjusts the drilling fluid density to increase or decrease according to the entry into the high-pressure formation or low-pressure formation.

[0094] It can be understood that the above-mentioned various embodiments mentioned in the present application can be combined with each other to form a combined embodiment without deviating from the principle logic.

[0095] The present application draws several curves of DC index, drilling pressure, mud density, pump pressure and / or temperature while drilling, and uses the changes of these curves to monitor formation pressure, can comprehensively analyze drilling conditions, prevent misjudgment when monitoring by a DC index curve, can predict downhole faults, continuously monitor, record and correct the drillability index (DC index) of formation during drilling, simultaneously monitor and record mud density and drilling pressure and other parameters, has important significance for formation pressure prediction and balanced drilling guidance. According to the change of formation pressure, drilling fluid density is adjusted in time, so that the purpose of fast drilling, protecting oil reservoir and preventing oil reservoir pollution can be achieved, and drilling cost can be saved and construction safety can be ensured.

[0096] The above has described various embodiments of the present application, the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without deviating from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application or technical improvement in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A formation pressure monitoring system based on the DC index, characterized in that, include: Parameter detection unit and main control unit; The main control unit is used to plot the formation pressure monitoring related curve of the target well based on the formation pressure monitoring related parameters detected by the parameter detection unit. The formation pressure monitoring related parameters include at least: real-time pump pressure, real-time drilling fluid density, and real-time drilling pressure. The formation pressure monitoring related curve includes at least: pump pressure change curve, drilling fluid density change curve, and drilling pressure change curve. The main control unit is used to determine the DC index of the target well based on the formation pressure monitoring parameters and to plot the DC index change curve. The main control unit monitors the formation pressure of the target well based on the formation pressure monitoring correlation curve and the DC index change curve.

2. The formation pressure monitoring system based on the DC index according to claim 1, characterized in that, The parameter detection unit includes: a pump pressure sensor and a first wireless transmission module; The pump pressure sensor is connected to the main control unit via the first wireless transmission module; The pump pressure sensor is installed inside the mud pump set of the target well. The pump pressure sensor is used to detect the real-time pump pressure inside the mud pump set and transmit it to the main control unit through the first wireless transmission module.

3. The formation pressure monitoring system based on the DC index according to claim 2, characterized in that, The parameter detection unit also includes: a drilling fluid density sensor and a second wireless transmission module; The drilling fluid density sensor is connected to the main control unit via the second wireless transmission module; The drilling fluid density sensor is installed inside the mud tank of the target well. The drilling fluid density sensor is used to detect the real-time drilling fluid density inside the mud tank and transmit it to the main control unit through the second wireless transmission module.

4. The formation pressure monitoring system based on the DC index according to claim 2, characterized in that, The parameter detection unit also includes: a weight sensor and a third wireless transmission module; The weight sensor is connected to the main control unit via the third wireless transmission module; The suspended weight sensor is installed on the drilling rig. The suspended weight sensor is used to detect the weight of the drill string in the suspended state and the weight of the drill string during drilling, and sends it to the main control unit through the second wireless transmission module. The main control unit determines the real-time drilling pressure based on the weight of the drill string in the suspended state and the weight of the drill string during drilling.

5. The formation pressure monitoring system based on the DC index according to claim 1, characterized in that, The method for determining the DC index of the target well based on the formation pressure monitoring parameters includes: Obtain the target well's rotary table speed, mechanical speed, drill bit diameter, and normal formation pressure density; The target well DC index is determined based on the rotary table speed, mechanical speed, drill bit diameter, and normal formation pressure density, combined with the drilling fluid density and drilling pressure.

6. The formation pressure monitoring system based on the DC index according to claim 5, characterized in that, The method for determining the DC index of a target well based on the rotary table speed, mechanical speed, drill bit diameter, and normal formation pressure density, combined with the drilling fluid density and the drilling pressure, includes: The DC index is determined using formula (1); In the formula: ρ is the drilling fluid density, g / cm³ 3 R is the mechanical drilling rate, m / h; D is the drill bit diameter, mm; W is the drilling pressure, t; V is the rotary table or top drive rotation speed, r / min; Gn is the normal formation pressure density, g / cm³. 3 .

7. The formation pressure monitoring system based on the DC index according to claim 5, characterized in that, The parameter detection unit also includes: a turntable rotation speed sensor and a fourth wireless transmission module; A rotary table rotation speed sensor is installed on the drilling rig at the wellhead of the target well. The rotary table rotation speed sensor is used to detect the real-time rotary table rotation speed of the target well and transmit it to the main control unit through the fourth wireless transmission module.

8. The formation pressure monitoring system based on the DC index according to claim 1, characterized in that, The formation pressure monitoring parameters also include: real-time drilling fluid temperature; The formation pressure monitoring related curves also include: drilling fluid temperature change curves; The parameter detection unit also includes: a drilling fluid temperature sensor and a fifth wireless transmission module; The drilling fluid temperature sensor is installed.

9. The formation pressure monitoring system based on the DC index according to any one of claims 1-8, characterized in that, The method for the main control unit to monitor the formation pressure of the target well based on the pump pressure change curve, drilling fluid density change curve, drilling pressure change curve, and DC index change curve includes: The main control unit determines whether there is an abnormal curve among all the formation pressure monitoring related curves and DC index change curves. If so, the main control unit will issue a first-level alarm. The main control unit determines whether there are two abnormal curves in all the formation pressure monitoring related curves and DC index change curves at the same time. If so, the main control unit will issue a level two alarm. When a level two alarm occurs, the operator will shut down the target well for inspection. The main control unit determines whether there are more than three abnormal curves simultaneously among all the formation pressure monitoring related curves and DC index change curves. If so, the main control unit will issue a level three alarm. When a level three alarm occurs, the operator will perform drilling fluid density increase or decrease operations.

10. The formation pressure monitoring system based on the DC index according to claim 9, characterized in that, The abnormal curve is: If the curve rises or falls by more than its corresponding predetermined change value within a predetermined time range, then the curve is an abnormal curve.

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