Study on separation factor models for well anti-collision analysis

Rafael A Madeira,Dan Sui

doi:10.1007/s13202-021-01235-w

Rafael A Madeira, Dan Sui

Open Access

https://doi.org/10.1007/s13202-021-01235-w

Copy DOI

Abstract

Anti-collision analysis has been becoming even more important in the past few years with the increasing amount of wells drilled in highly congested fields. The separation factor (SF) is a critical safety parameter to avoid wellbore collisions, where the pedal curve method (PCM) is the commonly used way for the SF calculation. However, such method may be conservative in many situations and possibly triggers an unnecessary early stop drilling due to its conservation. In this study, our work aims to evaluate and compare the different types of the SF models. In addition, an alternative and supplement method of the PCM, called as elliptic cylinder of uncertainty (ECoU) method, is proposed. The radius of the ECoU considers the distance of the intersecting points of the center-to-center line and the cylinder surfaces of both reference and offset wells. By introducing the cylinder surfaces into the SF calculation, it could extend the collision avoidance along the whole well path to reduce multiple-points collision possibility. The findings in the study help us for better understanding of the SF analysis and also show that using the ECoU indication has a great potential in fields applications as a viable method to keep the drilling operations’ safety.

Highlights

BackgroundThe enhancement of the oil and gas recovery in mature fields is leading worldwide companies to increase a number of wellbores in the same area
The findings show that using the cylinder distances have a good potential as an alternative measure factor for anti-collision analysis
From the separation factor (SF) models analysis, it is clear that the model provided by the Industry Steering Committee on Wellbore Survey Accuracy (ISCWSA) is the most robust and less prone to numerical errors than the other two

Summary

Background

The enhancement of the oil and gas recovery in mature fields is leading worldwide companies to increase a number of wellbores in the same area. The anti-collision analysis identifies the position of a planned well in relation to other nearby wells It determines if a wellbore can be drilled safely without colliding with others. The Industry Steering Committee on Wellbore Survey Accuracy (ISCWSA), known as SPE Wellbore Positioning Technical Section (WPTS), was created to address the use and accuracy of the directional drilling instruments, and the issues related to anti-collision, well interception, and industry education, etc. They have been working through the years to promote the standardization of the anti-collision analysis. The SF calculated by the pedal curve radius (Lawrence 1972) can erroneously indicate that two wells (reference and offset wells) have collided

Objectives and novelty

Summary and conclusions