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Shaft integrity pre-judgment method

An integrity and pre-judgment technology, applied in the field of oil and gas wells, can solve the problems that the contribution of the integrity failure of the whole well is difficult to define, is too subjective, and has little guiding significance, and achieves strong model generalization ability, wide coverage, and accuracy high degree of effect

Pending Publication Date: 2021-06-15
CHINA NATIONAL OFFSHORE OIL (CHINA) CO LTD +1
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AI Technical Summary

Problems solved by technology

However, the existing methods do not consider the influence of various production factors on the one hand, and the value of the severity of failure consequences is too subjective, and the accuracy of the evaluation results is not high; on the other hand, it is difficult to define the contribution of each unit to the integrity failure of the whole well; in addition, , the existing evaluation methods have little guiding significance for practice, and it is impossible to predict the number of years of failure in the future

Method used

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Embodiment

[0058] Such as figure 1 As shown, a method for predicting wellbore integrity based on random forest algorithm provided by the present invention comprises the following steps:

[0059] 1) Establish big data samples: 1500 training samples {X 1 ,X 2 ,…X 6 ,X 7 ,C} as the following table. The seven attribute values: X 1 is the well type, X 2 For Ibetsu, X 3 Whether the casing is fully sealed for production, X 4 is the production time, X 5 is the reservoir temperature, X 6 is the reservoir pressure, X 7 for CO 2 Content; a conclusion value C indicates whether the wellbore of the well is complete, divided into two categories: "yes" or "no".

[0060] No. x 1 Well type

x 2 Ibetsu

x 3 Fully sealed

x 4 time

x 5 temperature

x 6 pressure

x 7 CO 2 content

C completeness 1 Naoi oil well yes 10 140 80 5％ no 2 Directional well oil well yes 12 120 64 8％ yes 3 Directional well gas well ...

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Abstract

The invention relates to a shaft integrity pre-judgment method. The method comprises the following steps of S1, establishing a big data sample according to existing oil and gas well data; S2, determining features of a well to be pre-judged; S3, randomly generating k data subsets from the big data sample; S4, calculating information gain rates of discrete attributes and continuous attributes of the k data subsets; S5, utilizing the information gain rate to split a subset, and establishing a first decision tree to a kth decision tree; and S6, placing the features of the well to be pre-judged in the kth decision tree, and voting to decide the shaft integrity of the well to be pre-judged in the nth year. The method overcomes the defects that an existing method is low in accuracy and prone to being interfered by abnormal data, and pre-judgment is not accurate due to the fact that factors such as production time, reservoir temperature and pressure are not considered.

Description

technical field [0001] The invention relates to the technical field of oil and gas wells, in particular to a method for predicting the integrity of a wellbore. Background technique [0002] The failure of wellbore integrity is one of the main risks faced in the production process of high-temperature and high-pressure oil and gas wells. It is characterized by the pressure phenomenon in the annular space where the pressure should be zero. Once oil and gas leakage occurs, it will seriously threaten the safety of personnel and equipment. At present, the failure of wellbore integrity is becoming more and more prominent in high-temperature and high-pressure oil and gas wells. For example, among the more than 16,000 production wells in the OCS area of ​​the Gulf of Mexico, 43% of them have annular pressure. [0003] Existing research on wellbore integrity mainly focuses on risk assessment, that is, to quantitatively calculate the integrity risk of target wells. The idea is to deco...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F16/2458G06F16/28G06K9/62G06Q50/02
CPCG06F16/2465G06F16/285G06Q50/02G06F18/24323
Inventor 袁俊亮殷志明范白涛李中幸雪松谢仁军周长所罗洪斌
Owner CHINA NATIONAL OFFSHORE OIL (CHINA) CO LTD