Logging identification method for carbonate rock cave filler

Abstract

The invention discloses a carbonate rock cave filler logging identification method, which comprises the following steps that a filler type logging characteristic intersection identification plate is established, the intersection identification plate displays logging characteristics corresponding to different types of fillers, and the logging characteristics comprise logging parameters; and for the filler to be detected, reading the logging characteristics of the carbonate rock filling cave with the filler, and then searching the filler corresponding to the read logging characteristics from the intersection identification chart, so as to obtain the type of the filler to be detected. According to the method, the effectiveness of the filling cave reservoir is evaluated, the invalid reservoir is identified, implementation of invalid measures is avoided to the maximum extent, and the identification method is low in cost and high in accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of cave filling identification, and specifically relates to a logging identification method for carbonate cave fillings. Background Art

[0002] The main reservoir space of carbonate reservoirs in Tahe Oilfield is caves formed by dissolution. It is found in actual drilled wells that most of the caves are filled with other types of rocks, resulting in a deterioration of the reservoir space. Therefore, it is necessary for us to determine whether the caves are filled and accurately identify the types of fillings. Previously, the types of filling rocks were mainly judged by the cuttings carried out by the mud during the drilling process, that is, mainly identified by the cuttings logging method. Currently, in order to improve the drilling efficiency, PDC bits (polycrystalline diamond compact bits) have replaced ordinary tricone bits. The cuttings drilled by PDC bits are very fine and almost powdery, which brings great difficulties and challenges to the cuttings logging work, and even situations may occur where the types of fillings cannot be identified or misidentified by cuttings logging.

[0003] Chinese Patent "Comprehensive Logging Evaluation Method for Caves in Carbonate Fault-karst Reservoirs" with the patent number CN109061763B describes a comprehensive logging evaluation method for caves in carbonate fault-karst reservoirs. The judgment of the genetic type of fillings is realized by calling the genetic type identification module of cave fillings, and the judgment of the lithological type of fillings is realized by calling the type discrimination module of cave fillings.

[0004] Chinese Patent "A Method for Constructing the Structural Model of Paleo-karst Fracture-vug in Carbonate Rocks" with the patent number CN114509809A constructs the structural model of paleo-karst fracture-vug in carbonate rocks. First, the paleo-karst fracture-vug bodies are characterized, then the external contours of the fracture-vug bodies are corrected, and the fillings inside the fracture-vug bodies are identified.

[0005] The existing identification process is relatively complex and the identification accuracy is not high.

[0006] Therefore, there is an urgent need to provide a method that can accurately identify the types of carbonate cave fillings, which has become an urgent technical problem to be solved by those skilled in the art. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a method for identifying the types of carbonate cave fillings, evaluates the effectiveness of the reservoir with filled caves, identifies ineffective reservoirs, and maximally avoids the implementation of ineffective measures. And this identification method has a low cost and high accuracy at the same time. The specific technical solutions are as follows:

[0008] A logging identification method for carbonate cave fillings includes the following steps:

[0009] S1. Establish a crossplot identification chart for logging characteristics of filling types. The crossplot identification chart shows the logging characteristics corresponding to different types of fillings, and the logging characteristics include logging parameters.

[0010] S2. For the filling to be detected, read the logging characteristics of the carbonate rock filled cave with this filling. Subsequently, find the filling corresponding to the read logging characteristics from the crossplot identification chart, that is, obtain the type of the filling to be detected.

[0011] Preferably, step S1 includes: performing core analysis on multiple wells respectively, thereby determining the types of different fillings located in the multiple wells, and obtaining the data of the logging characteristics of the multiple wells corresponding to the different types of fillings. Subsequently, establish the crossplot identification chart for logging characteristics of filling types.

[0012] Preferably, the logging parameters include natural gamma ray spectrometry, well diameter, resistivity, acoustic wave, density, and neutron.

[0013] Preferably, the logging parameters include gamma ray value without uranium, acoustic wave, density, and neutron.

[0014] Preferably, the logging characteristics further include electrical imaging.

[0015] Preferably, the determined types of different fillings include mudstone, sandstone, and breccia limestone.

[0016] The technical effects brought by this technical solution:

[0017] The present invention can effectively identify the types of carbonate rock cave fillings, and then evaluate the effectiveness of filled cave reservoirs, identify ineffective reservoirs, and provide good support for the completion plan of new carbonate rock wells and the reservoir reconstruction plan of old wells. Brief Description of the Drawings

[0018] Figure 1 It is a flowchart of a specific implementation manner of a logging identification method for carbonate rock cave fillings provided by the present invention;

[0019] Figure 2 It is a crossplot identification chart for logging characteristics of filling types in a specific implementation manner. The first figure is a crossplot of gamma ray value without uranium - density, the second figure is a crossplot of gamma ray value without uranium - acoustic wave, the third figure is a crossplot of gamma ray value without uranium - neutron, and the rhombus represents sandstone, the square represents mudstone, and the triangle represents breccia limestone. Detailed Description of the Invention

[0020] To solve the above - mentioned technical problems, the present invention provides a logging identification method for carbonate rock cave fillings.

[0021] Such as Figure 1-2As shown Figure 1 is a flowchart of a specific implementation manner of a logging identification method for carbonate rock cave fillings provided by the present invention; Figure 2 is a logging characteristic cross-plot identification chart for filling types in a specific implementation manner. The first chart is a chart of gamma ray without uranium-density cross-plot, the second chart is a chart of gamma ray without uranium-acoustic cross-plot, and the third chart is a chart of gamma ray without uranium-neutron cross-plot. And the rhombus represents sandstone, the square represents mudstone, and the triangle represents brecciated limestone.

[0022] The present invention uses "natural gamma ray spectrometry logging data" to determine the types of carbonate rock cave fillings, constructs logging identification charts for different cave fillings based on the reaction-sensitive parameters and logging response characteristics of different cave fillings, and automatically identifies the types of cave fillings according to the logging identification charts of different cave fillings in a complete process.

[0023] Through the observation, comparison, and lithological analysis of core data from cored wells in the Tahe Oilfield, it is determined that there are mainly three types of carbonate rock cave fillings: mudstone, sandstone, and brecciated limestone.

[0024] During the logging process, the natural gamma ray spectrometry, caliper, resistivity, acoustic wave, density, neutron, and electrical imaging obtained all have different response characteristics to the three fillings. Specifically, for mudstone: the gamma ray value without uranium is high, the caliper is enlarged, the resistivity value is low, the acoustic wave value is high, the density value is low, the neutron value is high, and it shows a dark and low-resistance characteristic on the electrical imaging map; for sandstone: the gamma ray value without uranium is relatively high, the caliper is not enlarged, the resistivity value is low, the acoustic wave value is high, the density value is low, the neutron value is high, and it shows a dark and layered low-resistance characteristic on the electrical imaging map; for limestone breccia: the gamma ray value without uranium is low, the caliper is not enlarged, the resistivity value is high, the acoustic wave value is low, the density value is high, the neutron value is low, and it shows a bright and high-resistance characteristic on the electrical imaging map. Use the gamma ray without uranium to make cross-plots with the acoustic wave, density, and neutron respectively to establish a logging cross-plot identification chart for caves filled with mudstone, sandstone, and brecciated limestone. Specifically, the gamma ray values without uranium corresponding to mudstone, sandstone, and brecciated limestone change significantly from high to low, and the density values change significantly from low to high; the gamma ray values without uranium corresponding to mudstone, sandstone, and brecciated limestone change significantly from high to low, and the acoustic wave values change significantly from high to low; the gamma ray values without uranium corresponding to mudstone, sandstone, and brecciated limestone change significantly from high to low, and the neutron values change significantly from high to low. Mudstone, sandstone, and brecciated limestone can be clearly identified from the cross-plot, as Figure 2 shown

[0025] When confirming the filling to be measured, there is no need to take out the core for analysis. Only by reading the gamma ray value without uranium, acoustic wave value, density value, and neutron value of the carbonate rock-filled cave, and using the established logging cross-plot identification chart for caves filled with mudstone, sandstone, and brecciated limestone for lithology identification, the types of cave fillings can be quickly and accurately identified.

Claims

1. A logging identification method for carbonate rock cave fillings, characterized in that, it includes the following steps: S1. Establish a logging feature cross-plot identification chart for filling types. This cross-plot identification chart shows the logging features corresponding to different types of fillings, and the logging features include logging parameters; S2. For the fillings to be detected, read the logging features of the carbonate rock filled caves with such fillings, and then find the fillings corresponding to the read logging features from the cross-plot identification chart, that is, obtain the types of the fillings to be detected.

2. The logging identification method for carbonate rock cave fillings according to claim 1, characterized in that, step S1 includes: performing core analysis on multiple wells respectively, further determining the types of different fillings located in the multiple wells, and obtaining the data of the logging features of the multiple wells corresponding to the different types of fillings, and then establishing the logging feature cross-plot identification chart for filling types.

3. The logging identification method for carbonate rock cave fillings according to claim 2, characterized in that, the logging parameters include natural gamma ray spectrometry, well diameter, resistivity, acoustic wave, density, and neutron.

4. The logging identification method for carbonate rock cave fillings according to claim 3, characterized in that, the logging parameters include gamma ray value without uranium, acoustic wave, density, and neutron.

5. The logging identification method for carbonate rock cave fillings according to claim 3, characterized in that, the logging features further include electrical imaging.

6. The logging identification method for carbonate rock cave fillings according to claim 3, characterized in that, the determined types of different fillings include mudstone, sandstone, and breccia limestone.

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