The Lower Lagunillas-03 reservoir, in Maracaibo Lake, Venezuela, has been producing for more than 80 years from La Rosa (25 API gravity) and Lower Lagunillas (19 API gravity) formations. The average pressure is less than a 1/3 of its oil bubble point pressure; whereas more than 70% of the OOIP remains in place. Several waterflooding projects (Modules) with different injection patterns have been implemented since last 40 years, which have shown different results in term of production behavior and oil recovery. Therefore, an optimal waterflooding scheme has not been identified yet for the fifth waterflooding module (Lower Lagunillas Formation) and also for future waterflooding modules to be implemented for revitalizing the potential of this mature reservoir. It is essential in this case to ascertain the objective of an optimal waterflooding scheme in order to unlock the promissory oil recovery potential considering current reservoir conditions and financial resources. This was accomplished based on an innovative hypotetico-deductive method, which considers cycles of formulation-testing-analysis-emerging of hypotheses (scenarios), and starts with the formulation of a simple or relevant hypothesis (expectation) about a feasible exploitation plan. It is tested using a numerical or analytical model campaigned with economical optimization workflow and its results inquires to evaluate the hypothesis in the light of initial expectations as discarded or chosen, or whether some emerging hypotheses might be conducted and others might not. In turn, they are cycled until analysis of prediction determines probity of hypotheses or the refined research of hypotheses is stopped. Contrary to initial expectations, many hypotheses about waterflooding patterns for the fifth module were tested, such as new horizontal injector-producer wells (direct line drive), inverted seven-spot, and inverted five-spot from existing wells. Nevertheless a substantially increased Net Present Value (2 times greater compared to Base Case) was reached by testing inverted five-spot patterns using infill drilling and extending the area to be flooded so that it emerges as a novel strategy for unlock the potential of this mature reservoir.

The workflow for mature-field redevelopment requires a multidisciplinary team to analyze, select, and rank well candidates for intervention and production optimization. An objective evaluation of the well's productivity and reserves is essential for identifying possible alternatives to increase production. For this study, an analysis was conducted on 152 wells from the Carito field. As the second-largest oilfield producer in the Maturin sub-basin of eastern Venezuela, the Carito field encompasses approximately 150 km2 and comprises the El Carito and Carito south reservoirs. The Carito reservoir presents a high degree of heterogeneity resulting from complex, compressional faulting and varying sediments and includes hydrocarbons containing gas, condensate, volatile, black oils, and tar mat (oil mixed with wet sand). The Carito south reservoir behaves like a black-oil reservoir. The workflow presented in this study identified 20 candidate wells ranked by their potential to increase production. An intervention plan was then defined and ranked according to technical and economic criteria. This paper presents the successful application of this methodology in the Carito field to improve well productivity by approximately 7,000 bpd, proving that the method can be easily adapted to other areas.