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In the present work, the phenomenon of the peritectic reaction was characterized in a medium-alloy steel. Several directional solidification and thermal-analysis experiments were done to investigate the reaction process. Directional solidification experiments carried out did not tend to show any direct evidence of a peritectic reaction. Microsegregation studies on the directionally solidified samples and those solidified under isothermal conditions bring out some interesting features. It has been documented that if the segregation ratio for Ni is higher than that for Cr, there is a correlation that the peritectic reaction had occurred in that region. On the other hand, a higher Cr segregation ratio as compared to Ni showed the possibility that the liquid had directly transformed to ␥-austenite without undergoing a peritectic reaction. Measurement of energies of transformations and the analysis of their values in different segments of the cooling-curve differential thermal analysis (DTA) experiments have helped in understanding the peritectic reaction. It is revealed that the transformation is more like diffusionless transformation, where ␥-austenite directly precipitates from ␦-ferrite. Indeed, this proposition is also supported by the segregation patterns for Cr and Ni obtained in the solidified samples of this steel during directional solidification and DTA experiments and also by calculations to show the presence of enough lattice defects or vacancies to aid the aforementioned transformation.

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The history of La Ceiba field began 10 years ago when six exploration wells were drilled to assess the potential of this field. The wells were drilled with several incidents of stuck pipe and the resulting necessary side-tracks to reach the final depth. Until last year no further attempt had been made to drill in this field. With little information available from the exploration wells concerning drilling practices, the drilling campaign began with the goal of improving the previous performance, making the drilling of the complete wells faster and safer than in the previous drilling. An engineering process was begun to find the best drilling solution for the field, starting with proven technologies such as positive displacement motors (PDM) and drill bits used in similar fields; however, this methods alone were not sufficient to meet the challenges of the field. New technologies were used for the different challenges and applications through coordinated work between the drilling engineering departments of the different parties involved in this field and using all the information available in the drill bit selection database, including logs and stability data for the tools selected to drill each phase of the wells. With evolution of the learning curve, drilling progressed from initial drilling involving 12 runs with time-consuming trips to surface to change either the drill bit or PDM, to drilling the same interval in 5 runs with the time on bottom increasing compare to previous experiences due to the introduction of tools more suitable to the environment requirements a rotary steerable systems (RSS) in combination with a specially designed drill bit. Problems commonly faced in the upper sections were, the trajectory was not strictly followed, were solved with the introduction of the RSS in this section; use of the tool saved 10 days of rig time and set a bench mark for the field and similar wells in western Venezuela. The development of this field shows that by solving the issues related to the well depth, temperature and constraints well design for these wells in western Venezuela, it will be possible to reach the oil reserves, at the same time decreasing the time spent in the drilling process.

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