Maximizing Production Data to Understand Well Connectivity, Connected Volume, and Drainage Area for Future Prediction of Reservoir

Abstract

Field C is located at Cepu Block, East Java. This structure is observed as a small closure reservoir with 1347 acre-ft net volume which discovers in 2012 and starts to put on production in 2017. There are 2 production wells (well-1 and well-2) and 1 suspended well (well-3) that drilled to the L layer with oil production. The recovery factor from this layer was predicted around 31.79% of OOIP. After producing for 9 months, the flowrate and flowing pressure from existing wells starting to decline followed with a significant increase of water. Investigation of this performance is conducted in order to evaluate well and reservoir surveillance as part of Layer L development plan.

The objectives of this study to obtain drainage area from two wells (Well-1 & Well-2), investigate well connectivity and discover potential of layer L for production optimization. Updating dynamic model of reservoir to do monitoring of performance becomes a challenge because lack of reservoir data such as static pressure data that rarely collect. Rate transient analysis method becomes an alternative method to help overcome those challenge by maximizing production data analysis from rate and tubing head
pressure to perform well and reservoir surveillance. Workflow in this analysis using the method of flowing material balance to define connected volume, typecurve analysis to define reservoir properties, and validate using multiwell models with history matching.

Analysis is focusing first on a well basis to determine well connectivity. Then continue to the reservoir basis using a multi-well model to understand the drainage at the reservoir level. So that it can be used as a reference to predict reservoir potential in layer L. The result said that from the well basis observation there’s water breakthrough from well-2 also interference indication between Well-1 and Well-2 so that connected volume from well basis need to validate to multi-well model. Analyzing to multi-well model brings a clue that those existing well have not reach their boundary yet during their production, the drainage area also has not reach Well-3 (suspended well) area located in the edge of reservoir. Further observation from well-3 production data can help to validate this study.