Poor cementing quality will easily lead to oil-water channeling in the well, which will not only affect the follow-up operation, but also destroy the in-situ stress balance in a region and cause casing damage in a large area. Therefore, cementing quality inspection is very necessary.
There are many methods to detect cementing quality, such as well temperature method, isotope tracer method, acoustic wave method and gamma density method. These methods have their own advantages and disadvantages. Using gamma density logging and acoustic variable density logging to comprehensively analyze the cementing quality of oil and water wells can learn from each other's strong points and solve the multi-solution problem in cementing quality testing.
1) Based on the analysis of the causes of micro-rings and their responses in acoustic logging and gamma density logging, an interpretation method for comprehensive evaluation of the first and second interface micro-rings in cementing is proposed.
2) According to the requirements of workover and other operations for cementing quality inspection, the estimation methods of cement filling rate and compressive strength of cement sheath in casing-formation annulus are studied with gamma density logging as the main method and acoustic logging as the auxiliary method.
3) Aiming at the unresolved problem of evaluating the cementation state of cement and stratum interface in cementing quality inspection, an evaluation method based on comprehensive analysis of acoustic logging, gamma density logging and natural gamma logging data is proposed.
4) In order to detect the circumferential cementation and loss of cement sheath outside casing, the method of inversing the local loss of cement sheath by using the eight-sector amplitude of sector cement cementation logging is studied, which greatly improves the circumferential resolution of cement sheath detection.
The comprehensive interpretation of cementing quality gives the cementation of the first and second interfaces, the filling rate and compressive strength of cement stone, and the leakage angle of cement ring, which is more accurate and comprehensive than the previous interpretation results.