Method for identifying low-order unconformity surfaces of carbonate rocks

A carbonate rock, identification method technology, applied in earth-moving drilling, wellbore/well components, etc., can solve the problems of low accuracy, difficulty in removing noise, and many interference factors

Active Publication Date: 2018-11-06
CHINA UNIV OF GEOSCIENCES (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these methods are mostly used to identify higher-level unconformities in clastic rock formations. Due to the fundamental differences in the physicochemical properties and genesis of clastic rocks and carbonate rocks, the existing methods are not suitable for low-order unconformities in carbonate rocks. Significant limitations exist in the recognition of integration
[0005] In addition, the existing unconformity identification methods are subject to many interference factors, it is difficult to remove noise, and the accuracy is low

Method used

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  • Method for identifying low-order unconformity surfaces of carbonate rocks
  • Method for identifying low-order unconformity surfaces of carbonate rocks
  • Method for identifying low-order unconformity surfaces of carbonate rocks

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] The method of the present invention is applied to four outcrops at different locations in the northwestern margin of the Tarim Basin to verify the effectiveness of using strontium to identify low-order unconformities in carbonate rocks.

[0040] For the fresh rock formations of the Yonganba outcrop section, operate as follows, see figure 1 Shown:

[0041] S1. Continuous collection of rock formation samples:

[0042] Use a shallow sampling rig to collect fresh rock formations in the outcrop section of Yong’anba in the northwest margin of the Tarim Basin, and sample at equal intervals in the vertical direction of the rock layer, with an interval of 1m; define each layer where the thickness value of the initial rock layer is located as a layer For each level, 3 samples were collected at each level. The sampling depth is 30 meters, and a total of 90 samples on 30 levels are collected.

[0043] S2. Sample pretreatment:

[0044] Grind each sample through a 200-300-mesh si...

Embodiment 2

[0076] Then the method of the present invention is applied to the formations of different ages in the Penglaiba profile in the northwest margin of the Tarim Basin.

[0077] Refer to Example 1 for the operation method, except that in the continuous collection of rock formation samples of S1, the sampling interval in the depth direction is 2m; and the sample pretreatment of S2 is ground by a high-energy grinder, and sieved with a 300-mesh sieve, and 10g is soaked To 50 ~ 200mL hydrofluoric acid solution, react under vacuum conditions, release CO 2 . Evaporate on the electric heating plate to drive away the hydrofluoric acid, then seal and dissolve with nitric acid and dilute, filter to remove slag, and use the clear liquid as the sample to be tested. Other operating steps are all the same as in Embodiment 1, and draw image 3 .

[0078] See image 3 As shown, the Sr concentration of 8 samples of the Lower Ordovician Yingshan Formation in the Penglaiba profile is in the range...

Embodiment 3

[0081] The present invention is applied to drilling in the Tabei area of ​​the Tarim Basin.

[0082] The operation method of this embodiment is shown in Embodiment 1, except that the high-resolution inductively coupled plasma mass spectrometer used in step S3 is a Nex-ION300D high-resolution inductively coupled plasma mass spectrometer, other operating steps refer to Embodiment 1, and draw Figure 4 . (The point values ​​on the straight line segment connecting the two points have been hidden in the figure. Since these point values ​​are not turning points, they have no meaning for display.)

[0083] see Figure 4As shown, Well S88 is located in the Tabei area of ​​the Tarim Basin, and drilled through the entire Ordovician Yingshan Formation with complete cores. According to the operation specification of the present invention, the Sr element test of the system is carried out to the coring section, and the strontium element concentration change diagram of the Yingshan Formati...

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Abstract

The invention relates to a method for identifying low-order unconformity surfaces of carbonate rocks. The method comprises the steps that the unconformity surfaces are identified according to concentration anomaly by measuring the concentration of a strontium (Sr) element in a rock sample. The reason of which concentration anomaly of the strontium is selected to identify and study the unconformitysurfaces is that other indexes including vanadium and nickel are prone to being affected by late diagenesis to cause unexpected changes, but Sr is very stable and cannot migrate due to the late diagenesis, the original sedimentary characteristics of the formation can truly be reflected, and the measurement of Sr concentration is highly operable and accurate. In particular, an irreplaceable role is played in identifying low-order unconformity of carbonate rocks which lack obvious angular contact relationship and biological fossil indicators. Abnormalities of Sr concentration with wider range (>=14 %) can indicate the existence of the unconformity surfaces. The method has the characteristics of obvious characteristics, high sensitivity, accurate conclusion, few interference factors, simpleoperation, time and labor saving, easy judgment, good universality and the like.

Description

technical field [0001] The invention relates to a method for identifying low-order unconformity surfaces of carbonate rocks. Background technique [0002] Unconformity refers to the strata contact relationship between the upper and lower sets of strata of different ages with sedimentary discontinuity or lack of strata, which is usually formed by regional crustal movement, sea level rise and fall or local tectonic action. The main oil and gas basins in my country have experienced tectonic movements such as Caledonian and Hercynian, forming a series of stratigraphic unconformities. These unconformities play an important role in controlling the generation, storage and accumulation of oil and gas resources, and the identification and research of unconformities are of great significance to oil and gas exploration and development. [0003] Unconformities of different orders develop in carbonate formations. Among them, the unconformity of the higher sequence mostly belongs to the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B49/00
CPCE21B49/00
Inventor 高志前樊太亮卫端
Owner CHINA UNIV OF GEOSCIENCES (BEIJING)
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