Study On A New High-temperature Cementing Material System And Curing Mechanism

With the increasing exploration and development of the deep oil and gas resources,the number of deep well and super deep well is increasing.Deep well cementing will encounter the problem of high temperture and high pressure in the first place.However,conventional cement formulations,consisting of the grade G cement and a certain amount of the additive materials(e.g.silicon.)system,currently used for high-temperature,cannot meet the cementing requirements in the high temperature circumstances(≥200℃).Research and development of new type high temperature cementing material is of great significance for deep high-temperature cementing.In this paper,we studied a new type of high-temperature cementing material system.We select suitable high temperature cementing materials consisted of active silicon oxide and calcium oxide by testing different hydrothermal materials’ static gel strength,setting time and compressive strength,and finally finded a cementing material system.After that,we studied the rules of hydrothermal synthesistest by testing the relationship between system’s compressive strength and main mineral component ratio,water solid ratio and particle size distribution.We designed a new type of high temperature cementing material system,which is suitable for 100~350℃,and studied the high-temperature curing mechanism using XRD,SEM,TEM and EDS analysis methods.Laboratory study showed that: the new high temperature cementing material system can react to generate curing product which can resist high-temperature from 100℃ to 350℃ by changing the system silicon oxide and calcium oxide II group assignment ratio,water solid ratio and particle size distribution under the circumstances of high-temperature and water.The curing product has excellent properties such as high and stable compressive strength,low permeability,micro expansion,etc;The curing product consist of the type III CSH gel(100~200℃),tobey mullite(150~300℃)and xonotlite(200~350℃),and these type of curing products constantly enrich with time.Increasing the system Ca / Si molar ratio(Ca / Si ratio is less than or equal to 1)contribute to generate the tobey mullite and the xonotlite.Active silicon oxide particle size and water solid ratio have basically no impact on the type of hydrothermal system product.Tobey mullite and xonotlite have excellent performance resisted high-temperature,and can be interwoven into a dense three-dimensional network structure.All in all,the system has an ideal mechanical property resisted high temperature,which can meet the cementing demands under high-temperature.