An Advanced Three Phases Allocation Approach in Multi-Stacked Reservoirs with High Complexity on Historical Data During Field Development Plan
Authors: Majidaie Saeed , B Yakup Muhammad Hamzi , Bt Idris Nurul Nadhira , Khanifar Ahmad , Kechut Nor Idah , Benayad Nourreddine 
Published: October 2022

Abstract
Quality of commingled production data and reliability of back-allocation from stacked reservoirs with numerous platforms, wells, and strings play an important role in reservoir simulation modeling for history matching and prediction. A long historical data, limited surveillance data including routine well tests, pressure, and PLT, relying on conventional back-allocation for high water-cut strings with tubing integrity issues are the common pain points. The pre-HM tool is developed to provide a reliable and clean dataset for modeling.
Pre-HM tool includes advanced functionalities such as data quality index (DQI), areal-vertical multiphase allocation, integrated allocation, leak identification and quantification. DQI is designed for a systematic interpretation to identify missing data, potential errors, and outliers in historical data. Multi-phase allocation helps to improve areal and vertical allocation based on the water cut behavior type curve compared to the conventional KH-method. Integrated allocation is designed to handle the uncertainties associated with metering and back-allocation using the multi-solutions approach. Clustering and ranking processes for similar solutions are validated against material balance to propose the best solutions for modeling.
This technology has been deployed in several fields to examine the capability of different modules on the dataset. In most of the studies, the DQI module could demonstrate a rapid analysis of potential errors and outliers’ identifications in historical production data which was quantified by a 26% improvement. Moreover, the quality checking and cleaning process shows an improvement of 20 to 50% in timesaving compared to the conventional approach. Utilizing the advanced allocation results post DQI which were validated through material balance at reservoir sand package levels as input for the history matching process of simulation modeling works obtained a very good and reasonable history matching quality index (HMQI) improvement up to 25 to 35% in well levels. This improvement resulted in reasonable history matching without using unrealistic multipliers and reducing the uncertainties during prediction works. Leak assessment results proposed possible leaks in eleven wells which five of them were proven to have leaks based on available leak diagnostic job done by the operation team. An advanced multiple-solutions search engine combined with multi-phase deliverability models and material balance analysis to assess the uncertainty in the layer-phase allocation of different surveillance datasets compared to static KH-allocation.
This tool assists reservoir engineering with data quality checks and analyzing the historical production in an effective manner and provides an alternative solution to facilitate the history matching process in dynamic simulation modeling and reduce the uncertainties range. The multi-phase splitting factors is a key advanced feature compared to the single-phase method which is commonly used in the industry. This technology can be potentially deployed during any FDP project and simulation work.