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This paper describes the transformational application of Artificial Intelligence (AI) in Equinor's annual well planning and maturation process. Well planning is a complex decision-making process, like many other processes in the industry. There are thousands of choices, conflicting business drivers, lots of uncertainty, and hidden bias. These complexities all add up, which makes good decision making very hard. In this application, AI has been used for automated and unbiased evaluation of the full solution space, with the objective to optimize the selection of drilling campaigns while taking into account complex issues such as anti-collision with existing wells, drilling hazards and trade-offs between cost, value and risk. Designing drillable well trajectories involves a sequence of decisions, which makes the process very suitable for AI algorithms. Different solver architectures, or algorithms, can be used to play this game. This is similar to how companies such as Google-owned DeepMind develop customized solvers for games such as Go and StarCraft. The chosen method is a Tree Search algorithm with an evolutionary layer on top, providing a good balance in terms of performance (i.e., speed) vs. exploration capability (i.e., it looks "wide" in the option space). The algorithm has been deployed in a full stack web-based application that allows users to follow an end-2-end workflow: from defining well trajectory design rules and constraints to running the AI engine and evaluating results to the optimization of multi-well drilling campaigns based on risk, value and cost objectives. The full-size paper describes different Norwegian Continental Shelf (NCS) use cases of this AI assisted well trajectory planning. Results to-date indicate significant CAPEX savings potential and step-change improvements in decision speed (months to days) compared to routine manual workflows. There are very limited real transformative examples of Artificial Intelligence in multi- disciplinary workflows. This paper therefore gives a unique insight how a combination of data science, domain expertise and end user feedback can lead to powerful and transformative AI solutions – implemented at scale within an existing organization.

The purpose of this study was to evaluate the effects of preoperative external cobalt 60 beam irradiation on nerve regeneration. Ninety 250-g male Sprague-Dawley rats were studied. Peripheral nerve regeneration was measured by walking track analysis and histomorphology of the proximal, grafted, and distal nerve segments. Ninety animals were randomly assigned to one of five treatment groups, receiving a total fractionated dose of 30, 50, 70, and 90 Gy. Each animal received a 15-mm interposition nerve graft into the right posterior tibial nerve 6 weeks following completion of radiation therapy. The left leg served as a control. The remaining 10 animals received a nerve isograft subjected to a single dose of 30 Gy prior to placement (group 5). Walking track analysis was performed monthly through 8 months. At the conclusion of 120 and 240 days, sections of the proximal, grafted, and distal nerve were harvested, stained, and examined histomorphologically. Evaluation of the print length index demonstrated no statistical difference between our previously established nonirradiated controls, the irradiated groups, and the irradiated isograft group (group 5). The total number of axons per square millimeter was significantly decreased in the distal segment of all irradiated groups when compared with the controls. No statistical difference in number of axons per square millimeter was noted in the irradiated isograft group. Furthermore, no statistical difference was noted in the nerve fiber density between the control group, the preoperative irradiated groups, or the irradiated isograft group (group 5). Despite the reduction in myelinated regenerating fibers, no reduction in function was observed as measured by walking track analysis. Thus, immediate reconstruction of peripheral nerve defects in the face of preoperative irradiation may not be contraindicated.

This study investigates the histomorphologic and functional effects of external-beam irradiation on peripheral nerve regeneration in the rat model. All animals received a 1.5-cm interposition isogeneic nerve graft to the right posterior tibial nerve. Group 1 animals served as controls and Groups 2 and 3 received fractionated postoperative irradiation doses of 66 and 106 Gy, respectively. All animals were evaluated for functional recovery with monthly walking-track analysis. At the end of 8 months, the animals were sacrificed and segments of the grafted and distal nerve were harvested for histomorphologic analysis. A statistically significantly fewer number of axons were found in the distal segment of the irradiated specimens, compared to controls. There was no significant difference in the nerve-fiber density of the grafted or distal segments, compared to controls. Functional evaluation by walking-track analysis showed no difference between the irradiated groups and controls over the length of the study. These results suggest that acute nerve grafting of nerve defects in the face of planned postoperative irradiation is safe.

We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve, long bone, intestine, or blood vessel.

Introducion. Tissue engineering holds great promise for nerve replacement and restoration. The present study evaluated the efficacy of utilizing poly-DL-lactic-co-glycolic acid (PLGA) formed tubes through an extrusion process for peripheral nerve regeneration.