The Shushufindi field is located in the Oriente basin of Ecuador. The field was discovered in 1972 and is sparsely developed with about 200 wells covering an area of approximately 400 km2. An initial lithofacies characterization based on capillary pressures, pore throat size distribution, and log derived total porosities and permeabilities has provided a coherent grouping for the reservoir types that matched in over 92% of the wells. The importance of pore throat size in the initial lithofacies characterization has spurred the use of nuclear magnetic resonance (NMR) logs. NMR laboratory measurements on core samples complement the characterization with continuously calibrated pore body size derivations. Furthermore extensive whole core studies have shown that the pore throat size has a substantial impact on the initial oil saturation. Failures to respect this later point had previously generated disappointing oil production results. The challenge for the subsurface and engineering team is to take advantage of a lithofacies-based method to determine appropriate completion intervals and generate reliable production predictions. Open hole wireline log measurements of derived pore bodies size show a good correlation to NMR laboratory measurements on plugs when grouped within the initial lithofacies characterization. These data are used to provide a calibrated continuous pore body size curve based on the NMR binned porosities, and using the inferred initial oil saturation, to estimate the flow capacities for each lithofacies. This approach provides adequate support for selecting the reservoir rock with the best flow capacity, thereby optimizing the well completion. In thin beds where the vertical resolution of standard density and NMR logs is insufficient to discriminate the best facies a modified method has been developed. Very high resolution imaging has been coupled with flushed zone (Rxo) measurements and high frequency dielectric dispersion log to identify the potential production. This paper presents a lithofacies characterization enhancement methodology using NMR derived pore body size as implemented in the Shushufindi field, the results to date, its impact on the selection of completion intervals, and the resulting improvement in production from this technique.

Shushufindi is a mature oil producer field located in Ecuador; it was discovered in December 1968. For 20 years was development by foreign oil industry and then was transferred to national oil company. In February 2012 a contract was signed between Petroamazonas and Consorcio Shushufindi. Since this date until now the production has been incremented from 34800 bopd to 75000 bopd. The main Artificial Lift system applied to the field is electro submersible pump (ESP). High water cut, scale, low pressure, gas production, corrosion and other are problems that have presented in the wells affecting the run life of ESP. A Multidisciplinary team has been created to work on a plan to improve the artificial lift system performance and increase production through the application of a monitoring and optimization process. Initially failure frequency was reported due to tubing casing communication, cable failure or motor failure. Therefore some optimization studies on these wells to use 12 and 18 pulses variable speed drive (VSD) instead of 6 pulses in order to minimize the harmonic distortion from the input side of the VSD. Where realize that, it is a common petroleum engineering practice to produce the oil with minimum operating cost, while maintaining the facilities to serve efficiently for its design life time. In the meantime the production rates of the well should be convenient to their capabilities. Any fault in the design of the proper production equipment for each well reduces the equipment life, increase maintenance cost, and workover need and, therefore, increase the total oil production cost. Performance indicators were established to evaluate the performance of electrical submersible pumps from the beginning of the contract. The ESP average run life is 669 days. On 2013 the percentage of indirect failures was 89.3% and direct failures 10.7%. Tubing Casing Communication failure is the most important which represents 49.7%.Actually there are 140 producers wells completed with ESP of which 64% has remote monitoring. Optimization studies on production parameters and operating conditions of ESP are continuously evaluated to perform increase of frequency, amperage consumption optimization, recommended operating range for ESP, downhole equipment replacement, equipment deeping, and others are done in order to increase production and ESP run life.

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.

The Shushufindi field, located in the Oriente basin of Ecuador, has been producing since 1972. In December 2011, the field had approximately 150 wells, with a total production of 45,000 bopd. Field operations were then passed to the Consorcio Shushufindi (CSSFD) led by Schlumberger for a period of 15 years. Since then, 30 new wells and 26 workovers have been completed by Schlumberger Production Management (SPM) in the field, with a production of 60,000 bopd in May 2013.A methodology with four successive distinct phases was created, aiming for a complete reservoir characterization over 18 months prior to delivering the five-year field development plan (FDP) in October 2013. Each petrophysical phase focused on providing a reliable basis for the first two years of operations, and regular updates to the static and dynamic models.In conjunction with operations support, a comprehensive data acquisition plan was launched with advanced core analysis and special logs to support the advanced reservoir characterization. The deployment of technologies such as the Dielectric Scanner* multifrequency dielectric dispersion service, the combinable magnetic resonance tool, and the FMI* fullbore formation microimager, among others, was key in revealing the reservoir's true characteristics.Advanced petrophysics delivered a description of the main reservoir heterogeneities and properties, along with a facies characterization tied to an advanced core analysis including capillary pressure and pore throat size measurements. From this, hydraulic flow units were established in a deterministic characterization over the waterflood pilot well patterns. Additionally, a quantitative evaluation of thin beds and low resistivity pay zones provides the potential for their incorporation in the original oilin-place computation. These findings have contributed to a revision of the depositional concepts for the field.