Reservoir Architecture as a Driver for Effective Field Development Planning in an Un-Appraised Field; Kz field, Kazakhstan as a Case Study

Abstract

Successful oil and gas field development in clastic reservoirs is usually dependent on the amount of subsurface data available to be evaluated during field maturation. The general rule is that more data reduces subsurface uncertainties. This invites expensive appraisal campaigns that invariably leads to delays in investment decisions and increased costs in development projects. The present study highlights how the understanding and definition of the architecture of the reservoir coupled with the use of analogue database as a methodology can be used to enhance hydrocarbon development in fields that are not fully appraised. The un-appraised Kz field is used as a case study. Kz field, with an expectation In-Place oil of ca. 1150 MMstb is located SW of the Kashagan field in the Caspian Sea, Kazakhstan. The field consists of 11 stacked hydrocarbon-bearing reservoirs of varying thicknesses penetrated by a single exploration well. Due to the paucity of well penetration, subsurface uncertainty that impact on hydrocarbon volume and recovery is high. The methodology used was to combine the wells log and core data in addition to the use of sequence stratigraphic technique to derive sedimentological conceptual models. Analogue databases were then used to derive a geological meaningful range of dimensions for the geometry of the respective sand bodies. These ranges were then used an input for in-place volume ranges. Evaluation results showed a volume range that could support a go-forward decision for further investment in the field. Based on these results, some preliminary field development decisions were taken prior to dynamic simulation. Decisions include; (i) Drill six wells (ii) Do Multi-zone Well Completions and (iii) use two drill centers to optimally develop the field (Phase-1). The key strength of this approach is that some key Field Development decisions can already be made before appraisal using basic sedimentological concepts and analogue database studies.