THE MAIN PROBLEMS IN THE CEMENTING LONG EXTENDED REACH WELLS IN CUBA

Cuba advances in the development of drilling long extended reach wells (ERD). An extended range well is defined as one that has a true horizontal deviation-vertical depth (MD/TVD) ratio of more than 2.0. This relationship is an indication of the high complexity of conducting or constructing these types of wells: the higher the ratio, the more complex the well. It is important to note that this is only a basic indicator of the difficulty of drilling and completion of the well. Most of the recently developed wells of this type are in the north-west fields of Cuba, between the provinces of Havana and Matanzas. The True Vertical Depth (TVD) is 1,500 to 2,000 meters, and the horizontal displacement is up to 8,000 meters. However, experience has shown that the quality of the cementation of the extended reach wells in Cuba does not correspond to what is required. Among the most common problems affecting the cementation work of oil wells we can find the poor condition of the well (deviation, well stability, layer of cuts, etc.); poor condition of the mud (high gel stability, high circulation or filtration losses, high solids content, loss of circulating material, incompatibility between drilling fluid and cement); loss of circulation; abnormal pressures (abnormally low pressures, high pressures, etc.). One of the most complex problems to solve by well construction is poor centralization: cement is unevenly distributed throughout the cladding, leaving the cuttings in place. The paper reveals the main problems identified in the cementing long extended reach wells in Cuba and some technological proposals for their solution.