Enhancing Projects Value by Embedding the Full-Scale Production System into Reservoir Model – A Case Study of Karachaganak Field, Kazakhstan
Authors: Aktassov Kanat , Karlykhanov Yerzhan , Tleukhabyluly Olzhas , Imagambetov Kanat , Folefac Alexander , Uxukbayev Gadilbek , Abonaem Khaled , Muratbekov Said , Channa Tahir 
Published: November 2020

This paper presents a successful case study of building a robust “in-situ” Integrated Production Systems Model (IPSM) directly in Reservoir simulator (ECLIPSE) without adding complexity of third-party network simulators (e.g. PETEX) and scripts. Based on the case study, ECLIPSE based IPSM model has proved to add incremental value over standalone ECLIPSE model by providing more accurate production profiles and reducing development costs by avoiding “under-designing” or “over-designing” of project facilities.

High level group tree had been replaced by the detailed architecture that is well aligned with the actual surface field network layout. Considering the large number of production nodes, HFP (Horizontal flow performance) tables for existing and future pipelines generated and updated using the in-house developed automatic workflow based on OPEN SERVER platform and linked to the nodal analysis software. Flow rate-pressure calibration of simulated data to observed data across all 400+ manifolds, pipes and well chokes are performed beforehand based on regularly updated data from internal real-time production data management system.

The current reservoir pressure at Karachaganak gas condensate field (KGK) is below the saturation point. Producing Gas-Oil ratio and water cut at well and field level increases over production life that in turn creates bottlenecks in the surface gathering system. The production system includes around 200 production and injection wells connected to three inter-flowing processing facilities, which simultaneously constrained by gas and water processing capacities, gas compression for re-injection and contractual gas sale obligations. Recent practice for assessment of oil plateau extension projects in the field was to use either standalone ECLIPSE model option or full-scale Integrated Asset Model (IAM) based on integration of RESOLVE, GAP and ECLIPSE. ECLIPSE based IPSM model reproduced historical pressure losses of the surface pipelines at similar resolution of IAM model at much shorter computational runtimes. It also improved the rate-pressure transition from history to forecast in comparison with standalone results. In addition, new model setup helped to identify bottlenecks in the well flowlines and to propose solutions by properly rerouting the wells. Furthermore, significant CAPEX cost savings achieved by finding optimal size and number of trunklines from manifolds to Processing plants.

The novelty of this production-forecasting tool is the generation and integration of detailed surface gathering system into dynamic model without using third-party network simulators and to bring its accuracy to the levels sufficient not only for the long-term forecasting but also for medium-term and short-term optimization work. Mainly, this study is vital for a big oil and gas fields, where high precision is the critical for decision making and production success.