Unique laboratory tests of the domestic elastic self-healing cement system, under borehole conditions. Application experience

   Background. During the construction of wells, casing strings are cemented. One of the goals of cementing is the qualitative separation of the layers, but in the process of construction, development, and operation of the well, the cement stone may collapse. Violation of the cement stone can lead to leaks in cement stones and the occurrence of sustained casing pressure (SCP).

   The aim of this article is to describe the developed methodology for laboratory testing of a domestic self-healing cement system (SHC) on a unique TS-400 stand, which allows simulating downhole conditions such as pressure and temperature, as well as evaluating the impact of casing pressurizing on the integrity of cement stone and the effect of differential pressure on cement stone. The ability of self-healing of a SHC system in contact with hydrocarbons in conditions close to borehole conditions was also evaluated.

   Materials and methods. The test procedure and methodology were developed by the authors of this article to ensure maximum approximation to downhole conditions and processes that ensure the impact on cement stone in the well in accordance with the conditions at the Bovanenkovskoye field. The tests were carried out on a unique TS-400 stand.

   Results. As a result of the tests, the properties of the SHC to self-healing cracks in cement stone under borehole conditions (pressure, temperature) were confi rmed. The procedure for the formation of a program of non-standard tests has been developed. The nature of cracks in the cement stone, depending on the standoff of the casing, is noted. The results of cementing wells with SHC at one of the fi elds of the Gazprom Neft GC are described.

   Conclusions. A method for testing cement stones in borehole conditions has been developed. Tests of the SHC were carried out under borehole conditions at the TS-400 stand. The ability of the SHC to self-heal cement stone in contact with hydrocarbons has been confi rmed. The effectiveness of the use of SHC in ensuring the well integrity in the field has been confi rmed.

1. Denisov I.V., Gubzhokov V.B. Domestic elastic self-healing cement system as a method of preventing and elimination of sustained casing pressure and productive layers overfl ows. PROneft. Professionally about oil. 2023, no. 8 (2), рр. 40–49. (In Russ.) doi: 10.51890/2587-7399-2023-8-2-40-49

2. API Standart 65-part 2. Isolating Potential Flow Zones During Well Construction. December 2012, рр. 54–57.