Publications

Optimizing well architecture to manage declining trend of global oil and gas market, maturity of the gas field, and economical aspect of the well is a must right now. Shallow light architecture – as optimization result of this challenge – is implemented by targeting shallow reservoir zone to maintain its production level and reducing overall cost at the same time. From technical cementing point of view, shallow light architecture poses some challenges to provide proper zonal isolation. Quick gas migration and weak formation integrity that may lead to lost circulation are one of the main concerns. Moreover, lower temperature that affects development of compressive strength and requirement to start hydration from bottom to top (not simultaneous) have made cementing placement a little bit technically challenged. First cementation of shallow light architecture well was done with conventional cement system and technique resulting in unacceptable Cement Bond Log amplitudes (10 – 90 mV) with patches of free pipe. Post job evaluations with extensive lab tests were done to optimize cementing placement technique and fluids design. Best practices for cement placement were also reviewed and adopted to enhance the cementing procedure. Optimization of mud circulation cycles using low rheology mud, properly engineered spacer and lightweight gas tight slurry, utilization of pseudo-caliper, stand-off optimization at Interesting Zone interval depth and improvement of annular velocity have resulted in excellent Cement Bond Log reading (0 – 10 mV) of subsequent wells. This successful optimization had made shallow light architecture more productive and cost effective in marginal reserves than other well architecture targeting similar shallow zone reservoir. This paper presents the cementing design summary which focused on engineering improvements in spacer and slurry design, as well as cement placement techniques & procedures. The purpose of this publication is to capture and spread the best practices of cementing for shallow gas wells.