Compact Intelligent Completion: A Game Change for Shushufindi Field
Authors: Rodriguez J. C. , Dutan J. , Serrano G. , Sandoval L. M. , Arevalo J. C. , Suter A. 
Published: June 2014

Production in the Shushufindi-Aguarico oil field (SSFD), Ecuador, is from three stacked reservoir sands: basal Tena, U, and T. The SSFD is considered under saturated and is characterized as having two simultaneous driving mechanisms. The first mechanism is associated with solution gas drive, and the second is associated with an active bottom and lateral aquifer. This latter mechanism offers high recovery factors that oscillate between 25 and 30% and high water cut in most of the wells, especially in those producing from the T sand.

The reservoir is compartmentalized by stratigraphic pinchouts with the result that each of the sands has a different pressure regime: T sand from 2400 to 2600 psi, U sand from 1400 to 3000 psi, and basal Tena sand from 1200 psi. The reservoir pressure limits natural flow; therefore, artificial lift is required.

The dominant artificial lift method is the electric submersible pump (ESP), which is used in 106 wells. Other methods in the field are hydraulic pumping in 5 wells, gas lift in 1 well, and bean pumping in 1 well.

The saturation pressure for the U and T sands varies between 1010 and 1062 psi. Some wells are exploited with dynamic bottomhole pressure (Pwf) below the bubblepoint pressure; there are cases where Pwf is approximately 600 psi.

Originally, the casing used to complete wells in the field was 5 ½-in. × 17 lbm/ft and 7-in. × 26 to 29 lbm/ft. The wells perforated during the last 3 years have been completed with 9 5/8-in. × 47 to 53 lbm/ft casing and 7-in.× 29 lbm/ft or 26 lbm/ftliner. From the beginning of production in the field in 1970, a total of 140 ESPs have been run: 17 ESPs in 5 ½-in. casing, 39 ESPs in 7-in.casing, 42 ESPs in 9 5/8-in. casing, and 42 ESPs in 7-in. casing.

Wells are completed as monobore completions, either in the U or T sand, or have been selectively completed when both sands are to be exploited sequentially. The latter completion includes a sliding door to allow sequential production over time. In 2012, concentric dual completions were deployed in four wells, with some success. This technology involves high risk to the well operations because of its complexity (numerous accessories), tie drifts, and lack of flexibility to intervene the well with even a rigless intervention. Additionally, this completion technique requires high CAPEX and a considerable amount of surface equipment. This makes a future workover operation lengthy and risky.

A very important production consideration in this field is that the hydrocarbons regulatory authority in Ecuador, ARCH, does not allow the commingled exploitation of the U and T sands because of the issues this raises with reservoir management and petroleum accounting.

The technical and regulatory challenges are the drivers for considering intelligent completion (IC) or compact IC for the operator, Consorcio Shushufindi (CSSFD), and evaluating and testing IC and compact IC completions for this field are the objectives of the present technical work.

As part of this work, significant advances have been made in increasing the information that makes up the portfolio for a candidate well; this information includes a definition of the architecture required, conceptual simulations to estimate production rate for the sands, operation philosophy, advantages and disadvantages of the application, and antecedents worldwide. In addition, technical presentations have been conducted at all levels of management to explain the technical justification and the benefits of implementing IC completions in terms of production optimization, reserves development, reduction of formation damage induced by the effect of well intervention (recompletions), etc..

Based on early technical meetings with the ARCH, Petroamazonas (PAM), and the Hydrocarbon Secretary (SH), a pilot test has been approved which will implement and evaluate IC in five wells in the SSFD field.