In response to the highly volatile industry situation post-Covid19, E&P companies are abandoning or delaying exploration projects. It is anticipated that to meet growing energy demand in the future, it would require robust reservoir surveillance to improve individual well productivity. Production logging plays a key role in developing reservoir flow characterization and its integration with multiple data sources can allow for a holistic well dynamic description, leading to production enhancement on a well-by-well basis. Multiple case studies are presented in this work that propose a data-driven, integrated workflow which combines production logging data with plethora of under-utilized data sources to constitute an investigative analysis to solve water production conundrum. The workflow developed as part of this work incorporates three distinct stages. Firstly, an in-depth data analysis is conducted utilizing all historical production data/trends and well events to link it with water production as each will have its distinct impact on the type of production logging tools/techniques that would be deployed on the subject well to achieve job objectives. Secondly, real-time production logging is conducted to ensure job objectives as defined in stage one is being met which is crucial to the resultant wellbore zonal profiling. Finally, once the production log visual representation is created, various other open-hole petrophysical and cased-hole well integrity logs are analyzed to make sense of the derived results and suggest reasoning to the state of the reservoir production pertaining to producing water. The case studies discussed in this paper include the use of petrophysical logs, MDT formation testing data, ultrasonic cement evaluation logs, and production log time-lapse analysis. Integrating various data sources with production log analysis allowed for establishment of water production sources in the various case studies discussed. In one case, production related ambiguity was resolved by integrating formation testing and production logging data together. Another analysis revealed channeling behind the casing through a micro-channel in the cement which caused water to encroach shallow perforations. This highlighted the importance of azimuthal cement logging to detect small channels even when omni-directional sonic measurements are depicting good cement placement. Finally, through integrated time-lapse production log analysis, it was discovered how wellbore dynamics were changing chronologically.

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The Ratana Field is a gas condensate field located in the Potwar Basin of Pakistan, discovered in 1990. The field comprises several stacked reservoirs in a thrusted anticlinal fold with two main reservoir compartments, an eastern and a western, which are separated by the main thrusts, but appear to be in pressure continuity through a fracture network. Ratana-2 was the first well drilled in the western compartment which came on production from the Paleocene Patala Formation limestone reservoir and is a major producer in the field. Ratana-2 was subsequently deepened to the Jurassic Datta Formation but because of a stuck drill string in the hole all penetrated reservoirs (Chorgali/Sakesar, Patala, Lockhart and Datta) have been open to flow since November 2009. Well interventions are not therefore possible in Ratana-2 and production and reserves allocation based on limited dynamic data are thus very challenging. Surface-based parameters including water and gas composition analysis, wellhead shut-in pressures, surface production rates and other relevant data were used to perform production and reserves allocation by using a molar equation. The results of the molar equation predictions were cross-checked with the data from nearby well Ratana-4 which is also producing commingled from Paleocene and Jurassic age reservoirs since November 2015. Production logging surveys were acquired twice in over a period of six months and were consistent with the molar equation-derived formation-wise production allocation. Subsequently, the molar equation was used on the available surface data of Ratana-2 for the formation-wise production and reserves allocation and indicates for the first time that the Lockhart Formation as is a contributing reservoir in the Ratana Field and enabling the Lockhart Formation reserves to be booked after seven years of production.