Characterization of hydraulic unit and use of particle size distribution data for unconsolidated laminated sandstone formations

Abstract

This research focuses on two important main subjects. The first study aimed to characterize the hydraulic flow unit with core data obtained from a thin, highly laminated, partially unconsolidated, shale-silty sandstone formation. The second study investigated the use of particle size distribution data obtained from the same formation but from different sources in different areas of field development. Five different measurement methods were studied in detail to perform particle size analysis. At the beginning of the thesis, which is referred to as the HU characterization phase, laboratory examinations were carried out on 77 core samples that were extracted from certain regions of the sandstone formation. The permeability and porosity data that were acquired were subsequently analyzed. In addition, two independent methods were utilized for the purpose of investigating the flow zones of the reservoir, which exhibited varied flow characteristics. The first approach utilized the Flow Zone Indicator (FZI), created by Amaefule. This methodology is popularly known as the slope approach. For a long time, people have used this well-established method to differentiate between different rock zones inside the reservoir by evaluating their flow characteristics. The method relies on hydraulic units and cumulative frequency calculations. The analysis of the log (FZI) curve involved fitting lines with different slopes to the curve and grouping points with identical slopes into the same hydraulic unit. The second method allows for a quick understanding of the flow characteristics present in distinct reservoir regions as well as a comparison of the flow characteristics present in the numerous rock sections present in different reservoirs. Guo defined a parameter known as discrete rock types (DRT), also known as the quantitative method, which makes this possible. We use the FZI values to calculate the DRT, which yields a more comprehensive result. We carried out a comparison of the required calculations and hydraulic units for both systems to identify the advantages and disadvantages of each approach. The data clearly demonstrates that Guo method is an excellent approach for determining hydraulic units. This method exhibits more responsiveness to variations in the core data, resulting in a more comprehensive examination of hydraulic units. In contrast to the first strategy, which only identified four hydraulic units, the second approach was successful in identifying a total of eight hydraulic units. In addition, the second approach provides a comprehensive hydraulic system that consists of hydraulic units with equal numbers, arranged in numerical order from the most efficient to the least efficient, under circumstances when many reservoirs display flow parameters that are comparable to one another. In the second part of the thesis, particle size estimation is used to measure particle shape anisotropy and evaluate surface area regularity. The Particle Size Distribution (PSD) classifies solid particles based on their size, revealing the proportion of each size range to the total amount of solids present. The accurate PSD of unconsolidated reservoirs is an essential variable in the field development process. PSD data is crucial for drilling fluid optimization and designing gravel pack completions. PSD data is utilized for permeability estimation when core data is not available. This research used PSD data to look into different aspects of field development for a gas-bearing, unconsolidated laminated sandstone formation within a certain unconsolidated formation. In addition to the widely used techniques for acquiring PSD data, such as sieve and laser particle size measurement, PSD data was also obtained using microscopic view, thin section imaging, and scanning electron microscopy (SEM). PSD measurements were conducted by analyzing different sources of material, depending on how the data was utilized. The primary materials collected for analysis included cores, plugs, well cuttings, debris, solids, scaling and precipitation products from well clean-up, flowback, and DST operations, as well as scaling and precipitation products from core flow tests and proppants used for gravel pack well completion. Significant variations in the PSD data were detected in the field due to its varied lithology and minerals. Precise engineering methods were employed to evaluate, compile, and utilize PSD data for the optimization of drilling fluid, the design of gravel pack completions in cased holes, and the calculation of permeability. It was determined that appropriately sized CaCO 3 might serve as an efficient bridging agent for the formation, as the formation rock with an identified PSD could assist in the formation of a high-quality filter cake. Determined the optimal proppant size and screen size needed for a cased-hole gravel pack completion based on the formation's PSD. The absence of any notable sand generation in the field confirms the effectiveness of the gravel pack assembly in avoiding sanding. A strong connection was found between the air permeability measured on cleaned and humidity-dried plugs under confining stress and the air permeability derived using various equations. It was observed that while the permeability trends were similar, there were notable differences between the measured data from the plug and the estimated data from the PSD.