The Technology Study On The Cementing Cement Dynamic Process Simulation

As the current rapid development of China’s economy, oil and natural gas resource producing significant demand and dependence. To ensure national economic and energy security, oil exploration and development intensify, turn to deeper strata. The number of deep wells has been drilled more and more. The target strata of deep wells are buried deep and have complex geological conditions. The increasing depth of the exploration drilling and underground situation more complex, make cementing more difficulty. Deep borehole conditions are complex, long of open hole. Reservoir pressure system is not uniform; The higher formation pressure, usually has to be increased the mud density before intermediate and production casing running, and many wells are sensitive to the balance of the formation pressure, lost circulation will happen if mud density is a little higher, blowout will be happen. Shale’ water sensitivity is very strong, which is easy to collapse. Borehole is very irregular. Hole’ enlargement is serious. Which make paunch borehole and candied fruit hole widespread. According to the experience of domestic wells well cementing, casing cement floors are asked to return to the ground, leading to a long section of cementing Sealing. In summary, There usually exist following issues in the deep well cementing:the technical problems of long cementing segment; the cementing problems of slim hole and small gap; Narrow window of safety pressure and cementing leakage and gas channeling problems; Cementing Challenges in Deep horizontal wells,under the conditions of irregular borehole cementing quality. Therefore, we must make full consideration for small gap, eccentric annulus, poor high temperature factors in the construction design of cementing. Design the rational slurry column structure of cementing fluid, replacement of displacement and replacement of cement injection pump and so on, to achieve equilibrium pressure cementing. Furthermore, we should make dynamic analog calculation dynamic simulative in the process of cementing in order to achieve safe, reasonable, objective and efficient cementing.According the open hole section length of cementing fluid in the annulus, using integral method to calculate the annular volume of open hole section, thereby calculating the amount of cement is more accurate; Using a variety of cementing fluid flow model(Newton model、Bingham model、Power-low model、H-B model) to describe the rheological model, which makes the cementing fluid flow model to optimize. The theoretical with the practical methods, basing on different temperatures measured slurry six-speed viscometer readings, establish include all six-speed viscometer readings with temperature equation, fit the rheological parameters under different temperatures; Raised the calculation model of segment by the temperature; Consider the impact of the small gap annulus in the calculation of the cementing rheological parameters. Introduce the concept of eccentricity effect coefficient and the formula. Proposed discrimination standards of small-gap annular flow pattern and the formula for calculating the Reynolds number correction. Divide the annular space wells reasonable which give a comprehensive consideration of annular circulating temperature, small gap and eccentric annulus factors, etc. Calculate the friction pressure drop of the whole Well section using the appropriate rheological model, rheological parameters and different annular friction pressure drop under the conditions of the calculation model, creating calculation model of the deep and ultra-deep wells’ cementing rheological, and solute the replacement pump pressure and replacement displacement. Set up the calculation model of dynamic process of cementing which consider the possible effect of the "U" tube in the process of injection, to calculate the wellhead pressure, the actual flow of the well, the fluid surface location, the fluid in the liquid column length, the vacuum section length, the flow pattern of attention point and the annulus dynamic pressure of any concerns flow point of cementing, etc. All of these provide technical support of optimizing the cementing process.The research is finished when the author is engaged in the scientific research "The Cementing Quality Intelligent Control System". According to all the theories and design methods stated in the research and based on SQL Sever2008database, the author develops "The Software of Cementing Fluent Design" using Visual C#programming language. System software is running on Windows operating systems, which includes structure and dosage design of function module, the cementing fluid rheological design function module, cementing construction process design function module. System interface is simple, convenient operation, accurate calculation, illustrated, and calculation result can be output in the form of the Word.This system has been tested on various Wells of liaohe ancient block debugging. After analysing data of well cementing design and construction of data, it can be seen that theoretical model is reasonable, the design result is accord with the results of the construction and the error is small, which can meet the needs of cementing engineering.