Design method of deep complex stratum well bore structure based on risk assessment

Abstract

The invention relates to a design method of a deep complex stratum well bore structure based on risk assessment. The design method comprises the following steps: 1) preliminarily determining a casinglayer and a depth; 2) calculating to obtain a risk coefficient of each layer of sleeve; 3) analyzing and coordinating the risk of each layer of sleeve according to the principle that the shallow layerof sleeve shares more risks and the deep layer of sleeve shares less risks: judging whether the risk coefficient of each sleeve is greater than a safety threshold value K or not; checking the tripping-in depth: if the safety factor RNi of the casing pipe at the ith layer is greater than K, selecting the casing pipe layer with the minimum safety factor from the upper casing pipe layers, and deepening the tripping-in depth h of the casing pipe layer; and 4) repeating the steps 2)-3) until the risk coefficient of each layer of sleeve is smaller than the safety threshold K. According to the method, the risk of the deep well bore structure is properly moved upwards, more design space is provided for the layer and the depth of the sleeve of the deep stratum, the comprehensive risk of the wholewell bore structure is reduced to the maximum extent, and a guarantee is provided for safe and efficient drilling.

Description

technical field [0001] The invention relates to a risk assessment-based design method for well body structures in deep complex formations, and belongs to the technical field of oil and gas drilling. Background technique [0002] Wellbore structure design is one of the important contents of drilling engineering design. Whether the wellbore structure design scheme is reasonable or not directly affects whether the drilling and completion construction can be implemented safely and efficiently. [0003] There are many factors affecting the design of the wellbore structure, mainly including: drilling fluid safe density window, geological must-seal point, geological target and drilling cost and other factors. After the research and development of experts and scholars at home and abroad, the basic methods of wellbore structure design from bottom to top, top to bottom, from the middle to both sides and mixed design have been gradually formed, which provide drilling solutions for diff...

AI Technical Summary

Problems solved by technology

[0007] In view of the characteristics of insufficient knowledge of deep formation information and frequent downhole complex situations when drilling in deep and complex formations, the present invention moderately shifts the risks of deep wellbore structure upwards by coordinating the risks borne by casings at various levels, and provides casing layers for deep formations. Provides more design space and lower depth, minimizes the comprehensive risk of the entire wellbore structure, and provides guarantee for safe and efficient drilling

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