TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis 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 i nitial 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.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe heavy-oil reservoir Bachaquero-01, in the Lagunillas district of Venezuela's Lake Maracaibo, has been productive since 1934. Because the oil gravity is only 12º API, steam has been injected since 1971 to increase production. To further optimize production, stand-alone horizontal wells have been drilled since 1996. However, in only 4 months after steam was injected into the horizontal wells, a very fast decline of up to 50% of initial production was observed in these nongravelpacked wells.In a drilling-and-completion campaign from October 2000 to January 2001, 18 horizontal wells were successfully drilled and gravel-packed. In this paper we describe the gravel-pack techniques applied to minimize the rapidly declining rate of production in horizontal alternate steam-injection wells. We explain the method used for screen and gravel-size selection and summarize the completion operations and gravel-pack fluids that were used. We describe the modification of an existing hydraulic packer with a high-temperature seal of 600ºF-a combination used for the first time worldwide. Finally, we illustrate the successful drilling-and-completion campaign with case histories and production performance.The gravel-packed wells had an average increase of 15% productivity after 1 year with no sand production. The gravelpack operations were executed at a pump rate of 2 to 3 bbl/min with a sand concentration of 0.5 to 0.7 pounds of proppant per gallon added (ppa), observing continuous fluid returns of 50% to 80%. The packers were successfully field tested after a period of three weeks of steam injection.

One of old and most important West Venezuelan Oil fields is the LL-03 reservoir which has accumulated more than 1200 MMBN and actually represent the 30% medium oil daily production of Exploitation Unit "La Salina", Maracaibo District, PDVSA. This reservoir is characterized for contain 30% of shale with not consolidated sand at low pressure with 450 psi at 3500 feet of depth with interleayer of clay and high permeability with lost of severe circulation risks, in order to develop the reserves of 24° API oil it was designed and execute the secondary recovery project called Fase IV through instrumented horizontal wells into low-pressure zone. Due the depleted conditions of this reservoir it was begun the search of new alternatives for perforation fluids competitive at technical and economic levels, being one of the main challenges to ensure the success in the construction and completion for extend horizontal wells. After obtained the formulation of the optimal fluid to use it was come to design the directional plan and the mechanical completion for sand control, being considered in addition the use of permanent downhole gauge for pressure and temperature readings, conforming therefore the instrumented well. The stability of the system, the effectiveness of the saline seal and operational practice allowed the successful perforation of 3 instrumented horizontal wells (2 injectors and 1 producer) with the formulated saline fluid in a horizontal section of 2699 feet average without observe hole instability problems having completed the wells with mesh screen for sand control and permanent downhole gauge for pressure and temperature readings in a concentric string, after removing the filter cake generated by the perforating fluid it was obtained 22 months of continuous and stable production of 900 BNPD results Vs 450 BPPD expected for PB-763 well, opening opportunities for the perforation of 3 wells in similar conditions and it was begun the project for perforation of the first multilateral well in this same reservoir. INTRODUCTION The reservoir LL-03 of the Miocene from the Rosa Mediano field after 50 years of production maintains reserves surpluses in the order of the 340 MMBN with pressure levels that oscillate between 300 – 600 psi, reason why the drilling has been associated to the risk of lost of circulation. In order to increase the area of drainage in wells drilled in the LR-60 sand of this field, it was begun the construction of horizontal wells making an investigation of the fluid to use to maintain the stability of the hole in the whole horizontal section of production during the drilling, selecting water based system of "aphrons" obtaining excellent operational results allowing the construction and completion of the well, but unsuccessful production level due to the low obtained initial production, reason to perform a chemical treatment for the removal of the damage created by the filter cake generated by perforation fluids obtaining an initial production of 1300 BPD, which was lower than the expected potential. This field has been put under projects of secondary recovery by water injection to maintain the production present of the reservoir, such has been implanted from year 1979 with the construction of vertical wells, denominated Phase I, the second and third project called Phase II and Phase III with peripheral geometric adjustments of seven inverted points and beginning the injection from year 1985, next to this is made an extension of Phase I in 1999. Later to these advances of secondary recovery it was performed a study of simulation made to the LL-03 reservoir from year 2000, being created a new project of secondary recovery denominated Phase IV, which would have a horizontal well adjustment of extended arm (over 1000 feet of length in the horizontal section of production/injection), expecting to recover 70.48 MMBNP. In order to obtain the objective of this project it was made an investigation of the type of drilling fluid to use, initiating the study with the obtained experience years back with another system of fluid, the same one was evaluated technically and economically against other systems being very competitive, in addition it had to be of easy removal to satisfy the volumetric success.

Concurrently in the West of Venezuela, they have come proposing technicians to improve the recovery of oil weighed through of new processes of thermal stimulation that do not use water steam as agent of heating. In this work it is considered the injection of hot gasoil the reservoir and exists the thermal stimulation process´s physical mathematical foundation, based on the several mechanisms of heat transference as convection and conduction, as a whole with the mechanism of transference of matter for liquid diffusion - liquid, which one, it based in: A Balance of calorific energy, through it is determinated distribution of temperature in the reservoir, and the heat losses to the adjacent formations evaluated by the model of Marx and Langengein, besides the model of production defined by Boberg and Lantz. A Balance of matter ruled by Fick's Law of the diffusion oil -solvent, and the equation of difusitivity that governs the transitory behavior of pressure defined by Everdingen and Hurst. The stability of the simultaneous solution of the differential equations system is acceptable, due the founded solutions are analytical type. Operationally the efficiency of the stimulation and the field practice, they will be key points that there will allow the successful execution of the planned process, through the wells completation with sand control filters, sensors of pressure and temperature, besides the thermal equipments of completation that requiere the thermal processes. To illustrate the field application of the proposed technology, there was selected the reservoir Bachaquero-01. The results obtained in several running of sensibilities, indicate that it is achieved an increase obtains in the mobility factor of the oil at reservoir conditions of 10,5 times superior than the original one. Giving cycles of production of approximately 10 months, for a stimulated average rate with hot solvent of 850 BN/day versus stimulated average day with steam of 380 BN/day, in an arrangement of conformated wells by two horizontal ones in parallel. The obtained results indicate that the heat solvent injecting technology to the formation is more favorable alternative than the steam alternate injection process, due it is predicted a major optimized recovery of oil by cycle. INTRODUCTION The use of hydrocarbons solvent liquid, as the naphtha, kerosene, gasoil, they have been used to improve the process of the recovery of oil for steam injection, and to been reported and studied in a lot of works, even several processes have been patented depending on the type of solvent used, specifically in the injection of vapor/solvent. Allen (1976), proposed the use of a pot-hole of mixture composed by an aromatic hydrocarbon as solvent and a gaseous component as dioxide of carbon, to establish a preferential way between the well injector and the producer well, after which the oil is moved for constant injection of warm water or steam. Best (1979), Otherwise, he present a improved stimulation with steam in which one the oil in the formation is submitted to one o more steam cycles, followed of a pot-hole of mixture of a hydrocarbon solvent before the following cycle of steam injection. Later, Buckley and Grist (1980) propose the injection of a pot-hole of mixture of a distilled solvent, as tolueno or refined oil mixed with an oil sulfonato surfactante, in order to increase the permeability to the water in the reservoir before the injection of the steam. In this case, the proposed solvents and the schemes might be used in the cycles of steam injection, as well as in any process of thermal stimulation with steam. Islip y Shu (1984) present an invention that consists in the injection of a given quantity of a steam and solvent with the producer closed well. The injector well is then closed and the producer well is opened to extract the fluids from the formation, these stages are repeated cyclically in the time.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis 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 i nitial 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.