Enabling Technologies for Dynamic Reservoir Evaluation and Extended Pressure Transient Testing for the Low Carbon Transition
Authors:   Schlumberger, Jackson Richard , Gisolf Adriaan ,   Schlumberger, Dubost Francois ,   Schlumberger, Tao Chen ,   Schlumberger, Mayzenberg Nataliya ,   Schlumberger, Partouche Ashers ,   Schlumberger, Dumont Hadrien ,   Schlumberger, Yu Hua ,   Schlumberger
Published: October 2022

Oil companies are constantly trying to address uncertainties associated with reserve estimates and assessment of production, while rationalizing field development and production costs. To this capacity, formation testers are widely used to measure reservoir fluid gradients and reservoir pressure, obtain fluid samples, and assess reservoir connectivity. Dynamic data, acquired with interval pressure transient testing and well testing techniques, is used to assess reserves and productivity. However, these evaluation techniques provide dynamic data at different resolution and length scale, and with different environmental footprint, cost, and operational constraints. To help reduce development risks, an extended formation testing technique was developed in response to an industry and customer need. This technique, known as formation testing while tripping (FTWT), was introduced to the industry in 2015 with practical application around the world by a number of oil companies. The FTWT method, which was based on developments on an existing formation testing platform, integrated a number of innovations allowing pumping of large fluid volumes at higher rates, extending testing time, and circulating the produced fluids out of the well for safety and well control, without the requirement for surface flaring. These features enabled longer and safer tests, allowing deeper investigation into the reservoir compared to existing wireline transient testing techniques. Although test durations can be increased, this approach is not a replacement for a well-designed and conducted drillstem test (DST). Rather this is a method designed to bridge the information gap at the length scale between formation testing and conventional well tests. The development and introduction of a new formation testing platform with new architecture and sensor metrology has led to major improvements in capability for dynamic reservoir characterization. A new wireline formation testing technique known as deep transient testing (DTT) has been introduced, which offers significant advantages in capability and technical improvements over the previous FTWT technique. With DTT, the combination of extended flow times, increased flow volumes and rates, and new downhole pressure gauges has enabled dynamic characterization in thicker formation at higher permeability with a deeper volume of investigation than previously possible. Pressure transient testing and sampling results with application of the DTT technique is now becoming an important component in dynamic reservoir evaluation programs for addressing reservoir uncertainties and reservoir concerns during exploration and field development. The DTT technique also aligns with global sustainable development goals by enabling reductions in CO2 emissions by up to 96% percent, for the case of a 6- hour flow test at 100 B/D flow rate compared to a DST of 48 hours duration at 3000 B/D flow rate, albeit notwithstanding the difference of achievable objectives between the two techniques. Higher operational efficiency versus other wireline formation testing systems also reduces energy consumption by more than 50% - thus also significantly contributing to a reduction of emissions.