New Methodology for Quantitative Cement Evaluation Using Sonic Logging while Drilling:First Application in Middle East

摘要

Well Integrity is a major concern and a crucial step during the life cycle of the well.That is especially the case after the Macondo incident that changed the perspective of well integrity and proved how misinterpreting the data can lead to severe consequences to the safety of people,financial and environmental impacts.With the new innovations and technologies that we have nowadays,the oil and gas industry has expanded and entered more complex and challenging environments.The technological development of directional drilling allowed better reach and better oil and gas production from the reserves by using multiple angles while drilling.In Saudi Arabia,thousands of wells drilled each year where numerous cement integrity challenges faced especially in high angle wells.Wireline(WL)developed their tools over many years to provide an advanced assessment for cement bond evaluation with a reliable measurement.However,many local cases where observed where cement evaluation through WL was not a possible option due to some challenges such as well control issues and downhole condition.As a result,we needed to implement an alternative solution that can provide a quantitative cement evaluation through different means to address client challenges in cases where the WL service is not a valid option.Due to the high demand for real-time logging and rig time saving,Logging While Drilling(LWD)expanded its service offerings to address client challenges related to well integrity.In 2004,LWD started to provide top of cement(TOC)service utilizing its sonic tool that indicates qualitatively the presence or absence of cement in the annulus.However recently,LWD developed the first algorithms that delivers a quantitative cement evaluation through an LWD sonic tool utilizing a hybrid methodology.This new approach is a combination of two different types of interpretation which are amplitude-based and attenuation-based methodologies.This paper will present a successful trial test of the quantitative cement evaluation through LWD that was done in Hout Field in Saudi Arabia and verified with conventional WL cement bond log.The results of this test proved that LWD cement evaluation can be a viable alternative solution to running WL logs.Especially when the conveyance of WL is not feasible or even as a cost-effective solution to save tripping time.