Abstract

The Orinoco Oil Belt or “La Faja”, located in Venezuela, is the biggest reservoir in the world holding heavy and extra-heavy oil stored in highly permeable non-consolidated sands. To maximize reservoir exposure to production from these low pressure reservoirs, long horizontal sections in the reservoir are needed. Because of this, longer horizontal sections are being drilled and will continue to be drilled in the Faja.

The Faja reservoirs dip towards the north where drilling of horizontal wells has been concentrated in the last three decades, in wells drilled to true-vertical-depths (TVD) from 2,500 ft to 4,000 ft. As drilling in the last five years in Faja has moved towards the south, wells have been completed at TVDs from 1,500 ft to 4,000 ft. The recent development of the Junin Division of Faja, in the last two years, has required placing the wells at southern reservoirs at TVDs from 1,200 ft to 1,500 ft. Drilling these shallow horizontal wells demands adequate planning and execution to manage risks coming from high dogleg severities drilled with downhole motors, such as cyclic stresses of bottom hole components, high torque and drag, poor hole cleaning, inadequate weight-on-bit transfer, pipe swaps and stuck pipe events. Despite of the operational limitations seen when drilling shallow ERD wells with motors, a good number of wells recently drilled in southern Faja have reached important regional records of horizontal footage drilled. The current shallow horizontal record was drilled at 1,231 ft TVD; this well also coincides to be a record for Venezuela in terms of horizontal section drilled. The TVD over horizontal step-out ratio, or Extended Reach Drilling ratio (ERD), for this well was 1 to 4.4, which also constitutes a regional record.

After different operators drilled in Junin 28 shallow ERD wells with downhole motors, PDVSA, PetroMiranda and the service company tried out a point-the-bit RSS in three new shallow ERD wells. This paper presents the optimization experience using RSS to drill for the first time shallow ERD wells in Junin Division. An operational and technical comparison of RSS versus motors in Junin operations, as well as progress in the learning curve is also presented.

The experienced gained drilling horizontal sections of 28 shallow ERD with motors and three more wells drilled in the 8½-in. horizontal drain with RSS has become in an important performance step change to start planning drilling new southern blocks of Junin Division, where reservoirs could be as shallow as 1,000 ft.

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