Review and Analysis of Cuttings Transport in Complex Structural Wells

摘要

Complex structural wells are widely used in the development of marine oilfields, old oilfield sand lowpermeable oilfields. However, poor hole cleaning often occurred in the highly-deviated sections and horizontal sections ofthe complex structural wells, which affects rate of penetration, cementing quality and downhole safety. It is advisable tostudy the behavior of cuttings transport under different conditions. In general, experimental observations and CFDsimulations are main methods to analyze the effects of cutting parameters, fluid parameters and operational parameters onhole cleaning. The correlations and models are applied to predict the number of cuttings and the critical velocity in theannulus. In this paper, an analysis of key parameters is conducted on cuttings transport, the existing problems andcharacteristics of these correlations and models are summarized, and different removal methods of annular cuttings andfuture research needs are discussed. Although major improvements have been achieved in the past several decades, how toaccurately predict the cuttings bed height, critical velocity and other key parameters, and to effectively solve the poor holecleaning still is a difficulty challenge. Therefore, more research will be conducted to further understand cuttings transportmechanism in multi-factors coupling and complex wellbore conditions.