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This study is intended to show that it is possible to reduce risks, time and costs in well drilling through application of Geomechanics in marginal fields. It refers to the Oritupano-Leona field, East Venezuela, which has more than 700 wells drilled from 1938, 29 of which are horizontal wells. In spite of the production success, 6 over 29 wells, 25%, presented problems due to hole instability that lead to several stuck pipes, sidetracks and down time. Drilling parameters of 23 horizontal wells, operational problems, geomechanical information and regional geology were considered for this analysis. Problems associated to mechanical/chemical instability and operational problems were identified. Geomechanical parameters were calculated and analyzed with the specialized software considering pore pressures, mud density, minifrac and electrical logs, where the stress direction was studied with the interpretation of imaging logs and review of the regional stresses. A friction diagram adjusted to the wide of the breakout was applied, whereas vertical stresses were calculated through density log integration. Rock mechanical parameters were product of RSD tests that included rock mechanical resistance analysis (UCS), determination of the internal friction angle and the Poisson's ratio and Young modulus, calculated with the use of neural networks. Drilling events were visualized in order to define the stability frame of the area for the different operational parameters based in geomechanical parameters previously calculated. With this data a new well design was elaborated integrating trajectory optimization and operational parameters in order to diminish the stability problems. Different mechanical instability values were identified in the study in three zones of the field, and the safe operating window for drilling and operational parameters was identified for each one, guarantying hole cleaning. The application of the criteria and recommendations of the results of this study had an outstanding impact on the horizontal well drilling in the Oritupano-Leona field. In 2005, a new record was established with the drilling of the ORM-174, which is the fastest horizontal well drilled in the field history. Two other wells were drilled in 2006 with excellent results.

This paper describes 12 history cases of the successful applications of Alternate Path (shunt tube) Technology in wells in Bachaquero Lago, Tía Juana Lago and Lagomedio fields, in Lake Maracaibo.The use of divergent tubes combined with packoff in these wells, allowed to complete two zones in a single trip (stimulation or packing in the superior zone and packing in the inferior zone), reducing the number of pipe trips in each well and therefore, reducing the operational risks and drilling costs. This type of completion will also allow independent isolation in anyone of the zones in the event of watering problems, allowing selective production.In all the cases, successful gravel packing were achieved as well as 45% saving in drilling time, compared with conventional completion. In all the cases productivity was higher than the initial estimate, without formation sand production, confirming the success of the application.This technology provides a reliable and profitable alternative for the completion of two or three simultaneous zones.

Sand production is a well-known and costly problem in shallow unconsolidated sands. For years slotted liners have been used to control sand in these types of reservoirs. However, over time sand, fines and other debris can clog slots or make their way into the liner itself, thus blocking production. A new live-well intervention technique making use of a concentric coiled tubing (CCT) vacuum tool (VT) has been implemented in Venezuela1,2,3. The technique incorporates a venturi jet pump mounted on CCT, and is specifically designed to remove solids and/or fluids from the wellbore without placing hydrostatic loads on the reservoir. In sand vacuum mode, strong jets fluidize and mobilize solids into the vacuum as well as prevent a stuck pipe scenario. The jets also aid in opening clogged slots by loosening fines that may be blocking flow. When the VT applies suction, a localised pressure-influenced-zone is formed in the very near wellbore – thus providing an isolated ";point-load"; drawdown on the formation. The jetting action combined with point-load drawdown and drag forces results in solids removal from behind pipe as well as inside pipe. Evidence of this phenomenon are jobs where a solids volume greater than the entire liner has been retrieved to surface. Post job results on jobs performed in Venezuela consistently show reduced skin, increased Productivity Index (PI) and higher long-term oil production. This paper describes the latest in CCT vacuum technology as well as it improvement in time via case studies of several different applications in Venezuela. Also discussed are simple lab techniques, which reveal serious completion issues such as liner slot erosion, fines invasion and drilling fluid damage.