A method for detecting expansion rate of oil well cement

Abstract

The invention discloses a method for detecting the oil-well cement expansion rate, and belongs to the technical field of cement preparation. The method comprises the steps of slurrying, mould filling and curing and demoulding. The method is characterized by further comprising the steps of initial measurement, age period measurement and expansion rate calculation, wherein the curing and demoulding step comprises the process that a cement test block is put into a curing box, and demoulding is conducted after curing is conducted; the initial measurement step comprises the process that the direction of the cement test block subjected to demoulding is marked, then the cement test block is put into a measuring device subjected to zero correction, and the initial length L<0> of the cement test block is measured; the age period measurement step comprises the processes that the cement test block subjected to initial measurement is put into the curing box to be cured continuously, and the length L<x> of the corresponding age period is measured after the corresponding age period is achieved; the expansion rate calculation step comprises the process that the expansion rate is calculated according to the formula shown in the description, wherein 250 represents the effective length of the cement test block. According to the method for detecting the oil-well cement expansion rate, the expansion rate of the cement test block can be tested at different environmental temperatures, the testing data error can be reduced, and the measurement precision and accuracy of the expansion rate of the cement test block can be improved.

Description

technical field [0001] The invention relates to the technical field of cement preparation, in particular to a method for detecting the expansion rate of oil well cement. Background technique [0002] In the cementing process of oil and gas wells, gas channeling is a frequently encountered technical problem. Current research shows that there are several factors that lead to gas channeling. During the solidification process of cement slurry, due to the drop of liquid column pressure, shrinkage of cement stone, water loss of cement slurry, etc., an annular gap is formed between the cement sheath and the formation. Under formation pressure, oil and gas move upward along the cracks to other formations or wellheads. Especially in high-pressure wells and natural gas wells, the problem of gas channeling is more prominent, which not only seriously affects the production of oil and gas resources, pollutes other formations, and may even cause serious production safety accidents. In o...

AI Technical Summary

Problems solved by technology

The pavement cement concrete expansion coefficient testing device used in this detection method has an unreasonable structural design. First, it can only detect the expansion rate of cement stone at a curing temperature of 10-50 ° C, that is, the expansion rate of cement concrete for pavement, and cannot detect more. Expansion rate of cement stone under high ambient temperature; second, it is necessary to embed a temperature detector in the cement concrete test piece, which is difficult to recycle and reuse, and the material cost is high; third, the concrete test piece is fixed in the water tank and cannot be moved. During the test age, the displacement sensor cannot be reused

However, the ambient temperature of oil well cement varies greatly, and the properties of the expansion components of cement vary greatly at different temperatures. Using this device to test the expansion rate of oil well cement, there are large errors in the obtained data, which cannot provide information for oil well cement on site. Objective data reference makes it easy to form an annular gap between the oil well cement sheath and the formation, resulting in gas channeling and production safety accidents

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