Method for judging reasons for solid phase rise of drilling fluid

Abstract

The invention discloses a method for judging reasons for solid phase rise of drilling fluid. The method comprises the following steps: acquiring viscosity data and density data of the drilling fluid; judging whether the viscosity is increased to exceed a first threshold value or reduced to exceed a second threshold value according to the viscosity data; if the viscosity rise exceeds the first threshold value, whether the density data rise speed is larger than a third threshold value or not is judged, and if yes, it is determined that the solid phase rise reason is barite hydration; if not, determining that the solid phase rise is caused by mudstone invasion; if the viscosity is reduced to exceed a second threshold value, judging whether the density data rising speed is greater than a third threshold value, and if so, determining that the solid phase rising reason is metal mineral invasion; if not, determining that the solid phase rise is caused by sandstone invasion; according to the method, the reasons for solid phase rise of the drilling fluid can be rapidly judged through the viscosity and density change of the drilling fluid, and a scientific basis is provided for drilling fluid performance optimization and drilling risk control.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling, and in particular relates to a method for determining the cause of the increase of the solid phase of drilling fluid. Background Art

[0002] With the continuous growth of global energy demand, the exploration and development of oil and gas is becoming more and more frequent. As a key link in the exploration and development process, the efficiency and safety of drilling operations directly affect the economic value and development cost of oil and gas fields. In the drilling process, drilling fluid plays a vital role, including carrying cuttings, cooling and lubricating the drill bit, stabilizing the well wall, and controlling formation pressure.

[0003] In the actual drilling process, a preliminary judgment of the downhole conditions is often made based on the drilling fluid properties. These properties mainly include density, rheology, ion content, pH value, water loss and solid content. The comprehensive analysis of these performance indicators is crucial for evaluating the interaction between drilling fluid and formation, predicting potential drilling problems and optimizing drilling fluid formulation.

[0004] In the prior art, although the solid content of the drilling fluid can be monitored, it is difficult to determine the cause of the increase in the solid content, which is helpful in evaluating the downhole situation. Summary of the invention

[0005] The object of the present invention is to provide a method for determining the cause of the increase in the solid phase of drilling fluid, so as to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for determining the cause of the increase of the solid phase of a drilling fluid comprises the following steps:

[0008] Obtain the viscosity and density data of drilling fluid;

[0009] Determining, based on the viscosity data, whether the viscosity increases beyond a first threshold or decreases beyond a second threshold;

[0010] If the viscosity increases beyond the first threshold, determine whether the density data increase rate is greater than the third threshold. If so, determine that the cause of the solid phase increase is barite hydration; if not, determine that the cause of the solid phase increase is mudstone intrusion;

[0011] If the viscosity decreases by more than the second threshold, determine whether the density data increase rate is greater than the third threshold. If so, determine that the cause of the solid phase increase is the intrusion of metal minerals; if not, determine that the cause of the solid phase increase is the intrusion of sandstone.

[0012] The present invention determines the cause of the increase of the solid phase of the drilling fluid by the data changes of viscosity and density, and has a fast determination speed, which is conducive to quickly solving the downhole situation so as to take corresponding measures.

[0013] Further, judging whether the viscosity increases beyond a first threshold value according to the viscosity data includes:

[0014] Determine whether the viscosity increase exceeds 5%;

[0015] The step of judging whether the viscosity is reduced by more than a second threshold value according to the viscosity data comprises:

[0016] Determine whether the viscosity decrease exceeds 5%.

[0017] Further, the determining whether the density data increasing speed is greater than a third threshold comprises:

[0018] Determine that the density rises by more than 5%;

[0019] Determine whether the density increases by more than 10% within a predetermined time.

[0020] Furthermore, the predetermined time is 8-12 minutes.

[0021] Further, determining that the cause of the solid phase increase is mudstone intrusion includes:

[0022] Obtain the shear force, filtration loss and sand content of drilling fluid;

[0023] Determine whether the shear force, filtration loss and sand content have all increased;

[0024] If so, it is determined that the increase in solid phase is caused by the intrusion of mudstone.

[0025] Further, determining that the cause of the solid phase increase is sandstone intrusion includes:

[0026] Obtain the shear force, filtration loss and sand content of drilling fluid;

[0027] Determine whether the shear force, filtration loss and sand content have all increased;

[0028] If so, it is determined that the increase in solid phase is caused by the intrusion of sandstone.

[0029] Further, determining that the cause of the increase in solid phase is the intrusion of metal minerals includes:

[0030] Obtain the pH, color and conductivity of drilling fluid;

[0031] Determine whether the pH rises first and then falls, whether the color changes, and whether the conductivity increases within a predetermined time;

[0032] If both are true, it is determined that the increase in solid phase is caused by the intrusion of metal minerals.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention can quickly determine the cause of the increase in the solid phase of the drilling fluid through the viscosity and density changes of the drilling fluid, providing a scientific basis for optimizing the performance of the drilling fluid and controlling drilling risks.

[0035] (2) When the increase in solid phase is caused by mudstone intrusion, mudstone intrusion, and metal mineral intrusion, other characteristics (shear force, filtration loss, sand content, pH, etc.) can also be used for cross-verification to improve the accuracy of the judgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The flowchart of a method for determining the cause of the increase of the solid phase of drilling fluid in this embodiment. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0038] like Figure 1 As shown, this embodiment provides a method for determining the cause of the increase of the solid phase of the drilling fluid, comprising the following steps:

[0039] Obtain the viscosity and density data of drilling fluid;

[0040] In this embodiment, the viscosity data and density data of the drilling fluid are monitored in real time by the drilling fluid online monitoring equipment. Preferably, the drilling fluid online monitoring equipment may include the REALology intelligent drilling fluid performance online monitoring system. In this embodiment, in addition to being used to obtain the viscosity data and density data of the drilling fluid, the REALology intelligent drilling fluid performance online monitoring system can also be used to monitor multiple indicators such as the temperature, pH, oil-water ratio, and solid content of the drilling fluid.

[0041] Determining, based on the viscosity data, whether the viscosity increases beyond a first threshold or decreases beyond a second threshold;

[0042] If the viscosity increases beyond the first threshold, determine whether the density data increase rate is greater than the third threshold. If so, determine that the cause of the solid phase increase is barite hydration; if not, determine that the cause of the solid phase increase is mudstone intrusion;

[0043] If the viscosity decreases by more than the second threshold, determine whether the density data increase rate is greater than the third threshold. If so, determine that the cause of the solid phase increase is the intrusion of metal minerals; if not, determine that the cause of the solid phase increase is the intrusion of sandstone.

[0044] The present invention determines the cause of the increase of the solid phase of the drilling fluid by the data changes of viscosity and density, and has a fast determination speed, which is conducive to quickly solving the downhole situation so as to take corresponding measures.

[0045] In this embodiment, the solid content of the drilling fluid is regularly detected. When an increase in the solid content of the drilling fluid is detected, the cause of the increase in the solid content can be determined by the method provided in this embodiment. In this embodiment, whether the solid content is increased includes: whether the increase in the solid content exceeds 5%. If it exceeds 5%, the solid content is increased. In this embodiment, whether the increase in the solid content exceeds 5% means that in two solid content tests, the solid content of the second test is 5% higher than the solid content of the first test. For example, if the solid content of the first test is 3%, and the solid content of the second test is 6%, the solid content has increased by 100%. In this embodiment, the viscosity data and density data of the time period when the solid phase content of the drilling fluid increases can be selected to determine the cause of the increase in solid phase; the time period when the solid phase content of the drilling fluid increases refers to the time period when the solid phase content of the drilling fluid is detected to increase from low to high. For example, in one test, the solid phase content of the drilling fluid is detected to be 3%, and in the next test, the solid phase content of the drilling fluid is detected to be 6%. The time period between the two tests is the time period when the solid phase content of the drilling fluid increases; in this embodiment, after it is found that the solid phase content of the drilling fluid has increased, the cause of the increase in solid phase can be determined by the viscosity data and density data after the increase in solid phase content.

[0046] Further, judging whether the viscosity increases beyond a first threshold value according to the viscosity data includes:

[0047] Determine whether the viscosity increase exceeds 5%;

[0048] In this embodiment, when the viscosity increases by more than 5%, it is considered that the viscosity increases by more than the first threshold.

[0049] The step of judging whether the viscosity is reduced by more than a second threshold value according to the viscosity data comprises:

[0050] Determine whether the viscosity decreases by more than 5%;

[0051] In this embodiment, when the viscosity decreases by more than 5%, it is considered that the viscosity decrease exceeds the second threshold.

[0052] Further, the determining whether the density data increasing speed is greater than a third threshold comprises:

[0053] Determine that the density rises by more than 5%;

[0054] Determine whether the density increases by more than 10% within a predetermined time.

[0055] Furthermore, the predetermined time is 8-12 minutes. In the present embodiment, the predetermined time is preferably 10 minutes. For example, within 10 minutes, the density increases by more than 10%, which means that the density increase rate is greater than the third threshold value, that is, the density increases rapidly; within 10 minutes, the density increases by more than 5%, but not more than 10%, which means that the density increase rate is not greater than the third threshold value, that is, the density increases slowly.

[0056] Further, determining that the cause of the solid phase increase is mudstone intrusion includes:

[0057] Obtain the shear force, filtration loss and sand content of drilling fluid;

[0058] In this embodiment, the shear force of the drilling fluid can be measured by regular sampling of a buoy shear force meter, the filtration loss of the drilling fluid can be measured by an API filtration loss meter, a high-temperature and high-pressure filtration loss meter, a high-temperature and high-pressure dynamic filtration meter (HDF-1 type) and an intelligent fully automatic dynamic water loss meter (WT-Auto170-50 type) and other equipment, and the sand content of the drilling fluid can be measured by a drilling fluid sand content meter.

[0059] Determine whether the shear force, filtration loss and sand content have all increased;

[0060] If so, it is determined that the increase in solid phase is caused by the intrusion of mudstone.

[0061] Further, determining that the cause of the solid phase increase is sandstone intrusion includes:

[0062] Obtain the shear force, filtration loss and sand content of drilling fluid;

[0063] Determine whether the shear force, filtration loss and sand content have all increased;

[0064] If so, it is determined that the increase in solid phase is caused by the intrusion of sandstone.

[0065] In this embodiment, the shear force of the drilling fluid can also be monitored in real time by using an online drilling fluid monitoring device.

[0066] In this embodiment, the filtration loss and sand content of the drilling fluid are regularly tested. When an increase in the solid content of the drilling fluid is detected, the filtration loss and sand content can be tested according to the actual situation. For example, when an increase in the solid content of the drilling fluid is detected, the filtration loss and sand content of the drilling fluid can be tested immediately.

[0067] In this embodiment, the time period when the solid phase increases is preferentially selected to determine whether the shear force increases.

[0068] In this embodiment, the time period when the solid phase increases is preferentially selected to determine whether both the filtration loss and the sand content increase. If it is difficult to determine, the time period used for judgment can be appropriately expanded. For example, the filtration loss and sand content detection data twice before and after the time period when the solid phase increases are also used for judgment.

[0069] In this embodiment, whether the shear force, the filtration loss and the sand content are all increased means whether the data of the shear force, the filtration loss and the sand content are all increased by more than 5%.

[0070] Further, determining that the cause of the increase in solid phase is the intrusion of metal minerals includes:

[0071] Obtain the pH, color and conductivity of drilling fluid;

[0072] In this embodiment, the pH of the drilling fluid can be monitored in real time by using an online drilling fluid monitoring device.

[0073] In this embodiment, the color of the drilling fluid can be determined by visual inspection, color comparison card or spectrum analyzer.

[0074] In this embodiment, the conductivity of the drilling fluid may be measured by an ion concentration measurement module or a conductivity meter.

[0075] Determine whether the pH rises first and then falls, whether the color changes, and whether the conductivity increases within a predetermined time;

[0076] If both are true, it is determined that the increase in solid phase is caused by the intrusion of metal minerals.

[0077] In this embodiment, whether the pH rises first and then falls refers to whether the pH rises by more than 5% first and then falls by more than 5% from the highest point after the rise.

[0078] In this embodiment, whether the color changes refers to whether the color of the drilling fluid changes after the solid content increases compared with before the solid content increases.

[0079] In this embodiment, the conductivity of the drilling fluid is tested regularly. When an increase in the solid content of the drilling fluid is detected, the conductivity of the drilling fluid can be tested according to the actual situation. For example, when an increase in the solid content of the drilling fluid is detected, the conductivity of the drilling fluid can be tested immediately.

[0080] In this embodiment, whether the conductivity increases refers to whether the conductivity data increases by more than 5%.

[0081] In this embodiment, the color change of the drilling fluid means that the color of the drilling fluid may change to red, brown or light gray; for example, when the color of the drilling fluid changes to red or brown, it may be due to the intrusion of hematite powder or other iron-containing minerals, and when the color of the drilling fluid changes to light gray, it may be due to the intrusion of minerals such as aluminum oxide and magnesium oxide. Hematite powder, aluminum oxide minerals and magnesium oxide minerals are all metallic minerals.

[0082] After judging the cause of the solid phase increase through viscosity data and density data, the present invention can also verify the judgment result through multiple aspects such as shear force, filtration loss, sand content, pH, color and conductivity to improve the accuracy of the judgment.

[0083] As a specific application example of this embodiment, when drilling to 3543m in a well No. 3 in the Ledong Depression of the Qiongdongnan Basin in the western waters of the South China Sea of ​​CNOOC, it was monitored that the solid content of the drilling fluid increased significantly from 3% to 6%. Subsequently, the viscosity data and density data were observed during the period when the solid content increased from 3% to 6%, and it was found that the viscosity was relatively reduced, that is, the viscosity decreased by more than 5% in ten minutes, and the density showed an upward trend, but the speed was slow, that is, within ten minutes, the density increased by more than 5%, but not more than 10%. Therefore, it was judged that the reason for the increase in the solid phase of the drilling fluid was the invasion of sandstone; the changes in the shear force, filtration loss and sand content of the drilling fluid during the period when the solid content increased from 3% to 6% were continued to be observed, and it was found that the shear force, filtration loss and sand content of the drilling fluid increased during this period, so the above judgment can be successfully verified.

[0084] It should be noted that although the present invention is disclosed as above by specific embodiments, the above embodiments are not intended to limit the present invention. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for determining the cause of the increase in the solid phase of a drilling fluid, characterized in that: The following steps are involved: Obtain the viscosity and density data of drilling fluid; Determining, based on the viscosity data, whether the viscosity increases beyond a first threshold or decreases beyond a second threshold; If the viscosity increases beyond the first threshold, determine whether the density data increase rate is greater than the third threshold. If so, determine that the cause of the solid phase increase is barite hydration; if not, determine that the cause of the solid phase increase is mudstone intrusion; If the viscosity decreases by more than the second threshold, determine whether the density data increase rate is greater than the third threshold. If so, determine that the cause of the solid phase increase is the intrusion of metal minerals; if not, determine that the cause of the solid phase increase is the intrusion of sandstone.

2. The method for determining the cause of the increase of the solid phase of drilling fluid according to claim 1, characterized in that: The step of judging whether the viscosity increases beyond a first threshold value according to the viscosity data comprises: Determine whether the viscosity increase exceeds 5%; The step of judging whether the viscosity is reduced by more than a second threshold value according to the viscosity data comprises: Determine whether the viscosity decrease exceeds 5%.

3. The method for determining the cause of the increase of the solid phase of drilling fluid according to claim 1, characterized in that: The step of determining whether the density data increasing speed is greater than a third threshold comprises: Determine that the density rises by more than 5%; Determine whether the density increases by more than 10% within a predetermined time.

4. The method for determining the cause of the increase of the solid phase of drilling fluid according to any one of claims 2 or 3, characterized in that: The predetermined time is 8-12 minutes.

5. The method for determining the cause of the increase of the solid phase of drilling fluid according to claim 4, characterized in that: The determination that the cause of the solid phase increase is the intrusion of mudstone includes: Obtain the shear force, filtration loss and sand content of drilling fluid; Determine whether the shear force, filtration loss and sand content have all increased; If so, it is determined that the increase in solid phase is caused by the intrusion of mudstone.

6. The method for determining the cause of the increase of the solid phase of drilling fluid according to claim 4, characterized in that: Determining that the cause of the solid phase increase is the intrusion of sandstone includes: Obtain the shear force, filtration loss and sand content of drilling fluid; Determine whether the shear force, filtration loss and sand content have all increased; If so, it is determined that the increase in solid phase is caused by the intrusion of sandstone.

7. The method for determining the cause of the increase of the solid phase of drilling fluid according to claim 4, characterized in that: The determination that the cause of the solid phase increase is the intrusion of metal minerals includes: Obtain the pH, color and conductivity of drilling fluid; Determine whether the pH rises first and then falls, whether the color changes, and whether the conductivity increases within a predetermined time; If both are true, it is determined that the increase in solid phase is caused by the intrusion of metal minerals.

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