Reservoir Modeling and Production History Matching in A Triassic Naturally Fractured Carbonate Reservoir in Sichuan, China

DOI: 10.14800/IOGR.1155

Abstract

Fractures are observed on the image log data in many Triassic carbonate gas fields in the block located in Sichuan Basin, China, and clearly matched at the equivalent analogy outcrops. The pressure transient analysis test (PTA) after the field’s First Gas clearly implies a dual porosity dual permeability system. Sustained high gas rate from all producing wells and the communication between two well pads in distant indicate the significant role fractures play in well deliverability.

To support flow simulation, Discrete Fracture Networks (DFN) modelling was conducted with various static data as inputs. Multivariate Analysis (MVA) was carried out to ensure a quality correlation between reservoir and fracture properties which is the key for fracture modelling. The k_max/k_min ratio of the resulting elliptical fracture permeability tensors were scaled to an uncertainty range defined by integrating the core and FMI interpretation, equivalent outcrop study, and analogy data. The tensors throughout the model were then calibrated to the fracture component of isotropic permeability derived from well test.
  Prior to the simulation, the single well Inflow Performance Relationships (IPR) was calibrated to actual flow test results by adjustment in the simulation model. The production forecast shows that the reservoir depletion profile from the simulation model overlaps well with P/z versus three-year cumulative production based on PTA results, and the single well production from the simulation model matches actual data, indicating a reliable static reservoir model and dynamic simulation process.
  In brief, this presentation is to share the fit-for-purpose approach of reservoir modelling and history matching which has greatly helped better understand the dynamic performance of the reservoir, and therefore to guide optimal field development. The success can be tailored to other fields of similar kind.