New Life for a Mature Oil Province via a Massive Infill Drilling Program

Abstract

Breathing new life into a mature oil field is a challenge that has been facing national and private oil companies for almost as long as the oil industry has been in existence. Oil production from mature fields accounts for approximately 70% of the worldwide oil production. Unfortunately, more often than not, mature oil fields equate to high cost and low productivity, making mature fields unattractive when competing for resources with other options in a company's portfolio of investments. Major opportunities for production optimization in mature oil provinces are typically scarce, more so, if throughout the long lives of the fields nearly all conventional optimization strategies have already been attempted and implemented. The re-development project presented in this and its companion paper1 (SPE 104041) looked at the technical and business opportunities for two main re-development components. The first component aims to beat the natural production decline curve via the implementation of a massive infill drilling program; the second component aims to maintain production levels through the integration of various Improved Oil Recovery (IOR) methodologies. A multi-disciplinary team studied and recommended the implementation of a massive infill drilling program in a portion of Block 10, operated by Petrobras Energia Peru S.A. in the Talara area of Peru, to improve recoveries in a column of over 2,500 ft of shaly sands, with absolute permeabilities not higher than 1 md and with average well spacing already in the order of 20 Acre. The study included the design of the facilities to process and handle the incremental production. Analyses confirm that a massive infill drilling program would significantly increase the production in a period of 4 years, from current 3,200 bopd. The study also identified the areas with best potential for infill drilling. Among the sub-products developed in the study were a new production database to facilitate the task of mapping and calculating volumetrics, and a new methodology to estimate average net pay thickness from limited log information. The approach and methodologies developed for this project can be used to give new life to mature oil provinces around the world. Introduction The Block 10 (Lote X) of Petrobras Energia Peru S.A. (PESA) is located in the Talara basin, in the northwestern coastal region of Peru (Fig.1), and has an area of 470 sq. Km, all onshore. Oil and gas has been exploited in Block 10 since the early 1910's, mainly from formations of Tertiary age lying at depths ranging from 500 ft to 7,000 ft. As of today, there are in excess of 5,600 wells drilled in Block 10 and the current production is about 12,500 bopd. Perez Companc S.A., a company that was later acquired by PESA, started operations in the block in December 1996. For field management purposes, PESA has sub-divided Block 10 into four areas, namely Coastal, Central, Eastern and Southern (Fig. 2), comprising a total of 17 fields. For reservoir management purposes, the producing formations in Block 10 are grouped into Shallow, Intermediate and Deep formations. The investigation to asses the potential for a massive infill drilling program focuses exclusively on the Coastal area of Block 10, and on the Intermediate (Lutitas Talara, Echino and Ostrea) formations. Figure 3 is a generalized stratigraphic column of Block 10. The history of the Talara basin is very complex from the structural standpoint. It has been associated to subduction phenomena generally connected to tectonical and sedimentary processes, with mainly extensional events that generated intense distensile faulting. In the case of the Talara basin, the normal faults act as permeability barriers and also limit the continuity of the reservoirs. Figure 4 shows a structural map of the Coastal area of Block 10 at the Echino level, while Figure 5 is a cross-section selected arbitrarily, both with the purpose of illustrating the structural complexity of the reservoirs in Block 10. Note that for the purpose of this study, the Coastal area has been further sub-divided into five sub-blocks (Fig. 4).

Study of the mechanisms of streamline-adjustment-assisted heterogeneous combination flooding for enhanced oil recovery for post-polymer-flooded reservoirs

“…Well-pattern adjustment (Cipolla and Kyte 1992;Gould and Sarem 1989;Wu et al 1989) can further enhance the development performance of the non-main streamline area because the streamlines can be totally changed. According to the studies by Flores et al (2006), Sayyafzadeh et al (2010) and Rose et al (2011), well-pattern adjustment can induce the injected fluid to take effect in non-main streamline areas and further enlarge the sweeping area.…”