EFFECT OF TEMPERATURE AND ADDITIVES ON STRENGTH OF CLASS G OILWELL CEMENT

Strength properties of Class G oilwell cement are tested under different conditions by using a Static Gel Strength Analyzer,an High Temperature-High Pressure Curing Chamber and other instruments.Characteristics of development and change of compressive strength properties are studied under different temperature and additives.Critical temperatures at which the strength begin to decline are determined to be 110℃ and 150℃ respectively.When temperature exceeds 110℃,the strength will reduce after it reaches a certain value with the increase of curing time.The reasonable amounts of silica sand which will be added to cement slurry to enhance the strength of hardening paste are determined to be 30%~40%.The characteristics of development and change of compressive strength for cement slurry with silica sand are revealed,which there are a two-stage type and one-stage type within the temperature range of 110~150℃ and 150~200℃ respectively.The influence of additives on the strength and the scope of application of additives are analyzed.The nature which temperature etc.affects on strength properties is revealed.