The Pinda Reservoir was the first producing reservoir of the Lower Congo Basin in Angola and as such its mixed clastic and carbonate lithologies have been extensively characterized over the previous two decades. Understanding the Pinda Reservoir is often challenging due to highly complex lithologies and the relationships of secondary porosity to permeability. This paper describes how, use of advanced logging-while-drilling (LWD) imaging technologies, in combination with innovative real-time and post-processing methods delivers new insight into previously established interpretations of the reservoir.
The study used data acquired in two development wells drilled within the Pinda Reservoir offshore Angola. A selection of LWD images, of a quality never previously achieved within the Pinda Reservoir, were acquired. These included: bulk density, photoelectric effect, density correction (Delta-Rho), and high-resolution electrical images. In addition, real-time resistivity images were employed to identify intervals suitable for formation pressure testing and improve operational efficiency.
The overall objective of the acquisition programme was to effectively characterize the reservoir to the maximum possible extent given the technologies available. A key component of this was the imaging technology and examples are shown of the various image types and their associated interpretations. These included; structural dip computation, borehole quality indicators, sedimentological feature description, and characterization of fractures, faults and vugs as well as in-situ stress indicators.
Innovative methods of acquisition and analysis were deployed for the first time in Angola, delivering comprehensive evaluation of the formation and adding new understanding into what is historically the most significant producing reservoir in Angola. The operator now considers the acquisition of this type of data as a key component to the future development of the Pinda Reservoir.
The reservoir data used in this study was obtained from two wells (Angola_x12 and Angola_x15) which formed part of a three-well infield drilling programme undertaken in an offshore block Angola. The primary well objectives for Angola_x12 and Angola-x15 were to assess and produce hydrocarbon from the Pinda Reservoir.
