Eliminate losses in the production section

The operator wanted to eliminate losses in a challenging 6-in openhole production section. The narrow pore-pressure window and fracture gradients impose formation instability, leading to severe lost circulation problems during the construction phase and compromising zonal isolation objective of the well. The 4 1/2-in production liner on the first appraisal well was cemented with total losses, requiring the revision of the cementing strategy. Mitigation measures of strengthening the formation or adding lost circulation material (LCM) would be insufficient. The first attempt was made in the next well, where the production liner was cemented.

Maintain cementing ECD and obtain effective mud displacement

A mud weight reduction from 1.2 to 1.05 sg was proposed prior to cementing. MPD equipment including RCD 3 rotating control device system and SUPER AUTOCHOKE high-pressure drilling choke control system maintained constant bottomhole pressure. With the assistance of VIRTUAL HYDRAULICS drilling fluid simulation software, the operator created a well displacement schedule with the required surface backpressure adjustment. CEMENTICS zonal isolation software determined the optimal pumping and backpressure schedule to maintain the cementing ECD within acceptable range and obtain effective mud displacement. To further reduce the risk of loss circulation, CemNET advanced loss-control fiber technology was proposed to further reduce the risk of lost circulation.