Optimization of Well Testing for Current Reserves Estimation with Modern Wireline Formation Testers and Open Hole Logs in Exploration Wells Drilled in High Porosity Sandstone Suprasalt Sediments Field

Abstract

In Western Kazakhstan, post-salt high porosity clastic reservoirs of the Caspian Basin of Jurassic and Triassic age are represented by multilayer and multi-contact deposits having several gas-oil (GOC) and oil-water contacts (OWC), formed by channel deposits. Reservoirs have good formation properties. Application of advanced logging suite allows to delineate all the key reservoir properties, such as effective oil-saturated thicknesses, all the types of contacts (GOC, GWC, OWC) along with some other properties. However, in such type of reservoirs, it is important to determine a connectivity of individual lobes/lenses – different small parts of deposits. This can only be achieved via well testing and fluid sampling. Traditional well testing has long been a must during the exploration stage to obtain vital information on reservoir dynamic properties. Usually, it is rather a tedious and time-consuming process, especially when there are many uncertainties on reservoir fluid saturations that can lead to increased well construction costs. This paper will discuss an example on how to optimize and accelerate well testing stage using advanced wireline formation tester and extended logging methods in an open hole, which, in turn, allows for faster commissioning of reservoirs into production. It is important to note that wireline formation testers cannot fully replace traditional well testing of wells and reservoirs; however, they significantly expand and improve the capabilities traditional well testing has to offer. Therefore, the most optimal solution proposed by Embamunaigas was the joint use of results of wireline formation tester and traditional well test data in green fields. This workflow has successfully been tested in its license areas in recent years.