Use of graphs to assess well safety in drilling projects and during operations by identification of available barrier elements and consolidation of barrier envelopes

Two independent barrier envelopes are the usual requirement used in most well operations to avoid catastrophic accidents.These are classified as primary-concerning preventing the occurrence of a kick,and secondary-concerning controlling the kick to avoid a blowout.Barrier envelopes consist of barrier elements,thus verifying the quality of these elements is fundamental.Barrier elements may be either redundant or mandatory,and these relationships are what constitute the barrier envelopes.In this work,we present a methodology to evaluate well safety by identifying existing barrier elements and barrier envelopes and mapping their relationships through the usage of graphs technique.This technique explicitly states the relationship between barriers and between them and envelopes.It enables a simpler visualization for well designers and allows the development of computer programs to control the safety and integrity of wells,both in the design phase and during drilling.12 graphs are provided for a 4-phase well(conductor,surface,production,and drill-in),considering both the primary and secondary enve-lopes.Reasoning for constructing each graph is thoroughly provided.If these graphs are used,reliability values can then be assigned to each barrier element,which results in the reliability of entire barrier envelopes.This can be further extended to analyze the safety of each operation by applying the system to operational sequences and even comparing well designs.

Thermal performances and invisible thermal barrier formation mechanism of arc-shaped metal-fin-enhanced thermally activated building envelopes with directional heat charging feature

Thermally activated building envelopes(TABEs)are multifunctional component that combines structural and energy properties.Based on re-examining the heat charging processes,an arc-shaped metal-fin-enhanced TABE(Arc-finTABE)with directional heat charging features is proposed to optimize the thermal barrier formation process.A comprehensive parameterized analysis is conducted based on a validated mathematical model to explore the influence of 5 fin-structure design parameters and the static insulation thickness.Results verified that the directional charging strengthening fins can improve transient thermal performances of Arc-finATBE and enlarge horizontal and vertical sizes of the thermal energy accumulation area surrounding the pipeline,while the maximum growth in extra heat loss is less than 3.17%.From the perspective of promoting heat injection into expected areas,the straight main fin configurations with the angle of main fins of 30°,shank length ratio of 0.4 and no leftward mounted fins are preferred in load-reduction mode,while the angle of main fins of 150°,shank length ratio of 0.8 and multiple fin designs,especially with one of the main fins horizontally toward the indoor side,are more favorable in auxiliary-heating mode.Besides,it is recommended to add one arc-shaped branch fin to each main fin to achieve a balance between performance improvement and material usage.Moreover,branch fins with larger arc angles are preferred in auxiliary-heating mode,while smaller arc angles are conducive to injecting heat into the wall along main fins in load-reduction mode and preventing the heat near the inner surface from being extracted.Under the direct influence of the strengthened invisible thermal barrier,Arc-finTABEs can reduce the amount of static insulation layer by 20%–80%while achieving equivalent thermal performances as conventional high-performance walls.