Well Integrity – Managing the Risk Using Accurate Design Factors

Abstract

Abstract Wells closed in due to integry issues compose large volumes of recoverable hydrocarbons. In recent years, there has been advances in the understanding of pipe performance. The understanding of these advances is kept with a few specialists, and the industry standard remains unchanged for most engineers working with well intergrity. This paper shed light on these advances and the impact they have to well integrity. A modest estimate for an average well is an upfront saving potential of ~$45,000 USD for tubulars and a reduction of more than 50 metric tons of CO2 saving of the environment. The larger values, however, is with wells closed in due to integrity marginally under the acceptable. This article shows a hidden design margins. On average, pipe resistance to collapse is ~10 to 25% above the industry standard calculations. And for burst design, the real limit is often more than 7% higher than the industry standard calculations. Well integrity is a discipline ensuring safe hydrocarbon recovery on behalf of an operator. Every well is scrutinized and every signal outside the set boundaires from a well is ensued until the integrity is understood and a decision can be made to safely produce or to suspend the well. Well integrity is based on performance of the equipment in the barrier envelopes. Pipe is an important element in both the primary and secondary envelopes. Following a better understanding of pipe integrity, a new integrity work flow is proposed. Well Integrity is a relatively young discipline, where guidelines and stanards have evolved significantly over the last decade. There are still several important issues to be standardized, such as the minimum integrity information to be defined for a well. Examples are operational parameters such as (assumed) effective hole diameter, cementing parameters (rate, preflush, slurry, etc.) which have an impact to the integrity. Other important information to standardize is the restrictions in pressure testing of casing to avoid damage of the cement sheaths. Finally, this article proposes "information management" as the 4th element in the definition of well intergrity. The digitalization wave washing over the industry is about making optimal use of data, which is essential to make good decision in well integrity as much as any other area in the oil and gas industry.