Novel Liquid Foam Stabilizer for Cementing Applications

Abstract

Deepwater drilling and cementing have been a challenge due to the low temperature at seabed, low fracture gradients, shallow water flow, gas hydrates, etc. Foamed cementing is one of the best practices that have been used for deep water wells. Dry foam stabilizers have been used but are limited to the number of jobs achievable with pre-blended cement on the rig. Introducing a liquid foam stabilizer improves logistics and flexibility, so one type of cement can be used for all cementing jobs, including primary and remedial jobs. In this study, the performance of the novel liquid foam stabilizer was thoroughly evaluated with different types of cement and mixing fluid at various temperatures. API class H or class G cement with a foaming agent and the new foam stabilizer were mixed with fresh or sea water at different densities. The salt tolerance of the liquid foam stabilizer was investigated by adding a variety of salts at different concentrations. This liquid foam stabilizer also was evaluated at different concentrations and different foam qualities. The evaluation includes foam stability and density distribution of set cement. Both the set and unset foam stability were tested. The test results show that the liquid foam stabilizer significantly improves the foamed slurry stability and the density distribution of the set cement. The new liquid foam stabilizer helps foamed slurry and set cement stability with different types of cements, with fresh and sea water at temperatures from 40 to 190°F. In addition, it helps to improve system flexibility and logistics. Land and offshore applications of the new liquid foam stabilizer will also be described in detail.