Wellbore Strengthening through Squeeze Cementing: A Case Study

Abstract Formation strength is an important parameter in drilling operations pressure control because it indicates the wellbore pressure containment envelope above which fracture or rock matrix failure starts to occur and propagate if the pressure/stress is sustained. The rock mineralogy, the orientation of wellbore with respect to the direction of regional fault line, the stress regime as well as the permeability of the rock determines the manner in which the rock would fracture. During well operations, situations that may result in the fracture of one of the formations traversed by the wellbore could arise, in which case, the main operations focus shifts to ensuring that the fractured formation is repaired before normal well operations can resume. One of the techniques of reinforcing or repairing a fractured formation is Wellbore Strengthening; which employs a variety of technologies such as deployment of resins and specially designed cement slurry. Over the years squeeze cementing success has greatly improved through studies and using best practices; however, wellbore strengthening through squeeze cementing still poses unique challenges of determining the location of the fractures that need sealing; and also whether these fractures are compatible with the designed cement slurry. Thus squeeze cementing, while being economical and effective, will only succeed if the job is properly designed and executed. This paper will demonstrate, through actual results, the feasibility of squeeze cementing as a means to restore wellbore strength by explaining the basic engineering that goes into designing a successful squeeze cement job for this purpose. It focuses on describing how the multidisciplinary approach of rock geo-mechanics, lithology, fluid mechanics, cement slurry design and proper job execution can contribute to the success of wellbore strengthening through squeeze cementing.