Abstract
Achieving effective zonal isolation across multiple sections in the presence of weak formations is a significant challenge in the oil industry. The objective of this study is to address this challenge by discussing two successful primary cementing operations across total loss zones in deep gas wells.
In both cases, a meticulous approach was taken. The first involved a production casing, drilling from the previous casing string to the target depth, while the second operation was an intermediate casing. Despite encountering total losses while drilling, conventional lost circulation treatments failed, leading to blind drill the section. To address the zonal isolation challenge, a multi-stage cementing technique employing a novel plug and differential valve (DV) tool set was utilized, capable of withstanding pressure up to 3,000 psi. Extensive placement simulations were conducted to optimize mud removal and cement slurry design properties for the three-stage jobs.
The cement bond logs acquired post-operation exhibited excellent results, confirming successful zonal isolation in both cases. Despite encountering total loss zones, the meticulous planning and execution of the cementing process ensured achievement of the objectives. The utilization of the multi-stage cementing technique, coupled with the novel plug and DV tool set, proved instrumental in mitigating losses and enhancing cementing effectiveness. The comprehensive evaluation, including open hole (OH) caliper log assessment and extensive placement simulations, contributed to optimized mud removal and cement slurry design properties, further enhancing the success of the operations. Overall, this study highlights the efficacy of integrating advanced cementing techniques with detailed planning to overcome challenges associated with zonal isolation in weak formations. The successful outcomes of these operations highlight valuable insights that can inform and improve future cementing practices in similar challenging environments within the petroleum industry.
This paper presents a novel approach to cementing operations in challenging formations, particularly total loss zones encountered in deep gas wells. The utilization of a novel plug and DV set, capable of withstanding high pressures, offers a promising solution to enhance cementing operations in challenging conditions, contributing to the advancement of cementing practices in the petroleum industry.
