Exploitation Strategy in the Development of Gas and Oil Mature Fields: Case Study
Authors: Vega Riveros Gina Luz , Yehya Emad 
Published: April 2012

This paper presents the results of the exploitation strategy in the developmentof mature fields such as gas condensate and oil fields. For the gas condensatefield, the integration of the geology, seismic, production and reservoir hadallowed to define flow zones, and also had identified new opportunities fordrilling and then to establishing a strategy for a proper development of thefield under study.

The static and dynamic modeling teams have proven that the four studiedreservoirs in the gas condensate field could be unified in a unique hydraulicunit, and then they were created the static model accordingly. However, and dueto the scarcity of the available information, the official gas reserves wererevaluated and re-estimated using analytical methods (such as empiricalcorrelations, volumetric analysis and material balance). The empiricalcorrelations (such as Eaton and Jacobi) have been used to provide a rapidestimation of the gas condensate reserves. Both stand-alone and comingledproducing intervals have been also identified in the named hydraulic unit understudy.

According to this study results, the oil and gas condensate in place have beenincreased by 9% and 22% respectively compared with the official reserves. Material balance calculation had shown an gas condensate in place (GCIP) ofapproximately of 1,132 BSCF. The economical sensitivity analyses under variousscenarios have confirmed that the best option is to drill a horizontal wellwhich would be producing at different rates ranging between 600 STB/D and 1,500STB/D. The results have also shown that a higher profitability could be gainedfrom a horizontal versus an vertical well.

Therefore, a Field Development Plan (FDP) has been also established during thecourse of this work in order to define different forecasting scenarios. For theoil field case study, the strategy of exploitation can be clearly improved. Field Development Plan should incorporate future workover services, ESPs, gaslift optimization, water-flooding, infill drilling, twin wells, horizontalwells and appraisal wells which will surly add more recoverable oil that theconventional producing activities cannot achieve. A secondary recovery projectusing water-flood was recommended through a spot pattern simulation model. Inexploratory areas, the appraisal wells required the construction of productionforecast and reserve estimation under probabilistic scenarios and statisticaldata by extrapolation from surrounding wells supported by the use of 3-Dseismic. The good FDP would add an extra 50% of the nowadays production to thedaily field production by 2016.

Introduction

This paper presents two interdisciplinary study cases which were performed withthe integration of geology, seismic, production and reservoir to identify a newstrategy of exploitation in the gas and oil fields. The application of emergingtechnologies will make the extraction of hydrocarbons more competitive andprofitable.

In developed areas, this work includes the exploitation of several sands, hydraulic units, multiple hydraulic fracturing, new prospects such as infilldrilling, twins, ESPs, gas lift optimization, horizontal wells, multilateraland highly inclined wells to contact higher reservoir volumes, as well as theimpact on the production can be obtained. The exploratory areas are currentlyunderway because of the geological uncertainties (appraisals) and operationalrisks (offshore) which require the construction of production forecast andreserve estimation under various probabilistic scenarios and statistical datafrom surrounding wells. The performance predictions will be supported by theuse of 3-D seismic.