The Impact of Pore Structure on Kerogen Geomechanics

Production stimulation techniques such as the combination of hydraulic fracturing and lateral drilling have made exploiting unconventional formations economically feasible. Advancements in production aspects are not always in lockstep with our ability to predict and model the extent of a fracturing job. Shale is a clastic sedimentary rock composed of a complex mineralogy of clay, quartz, calcite, and fragments of an organic material known as kerogen. The latter, which consists of large chains of aromatic and aliphatic carbons, is highly elastic, a characteristic that impacts the geomechanics of a shale matrix. Following a molecular simulation approach, the objective of this work is to investigate kerogen’s petrophysics on a molecular level and link it to kerogen’s mechanical properties, considering some range of kerogen structures. Nanoporous kerogen structures across a range of densities were formed from single macromolecule units. Eight units were initially placed in a low-density cell. Then, a molecular dynamic protocol was followed to form a final structure with a density of 1.1 g/cc; the range of density values was consistent with what has been reported in the literature. The structures were subjected to petrophysical assessments including a helium porosity analysis and pore size distribution characterization. Mechanical properties such as Young’s modulus, bulk modulus, and Poisson ratio were calculated. The results revealed strong correlations among kerogen’s mechanical properties and petrophysics. The kerogen with the lowest porosity showed the highest degree of elasticity, followed by other structures that exhibited larger pores. The effect temperature and the fluid occupying the pore volume were also investigated. The results signify the impact of kerogen’s microscale intricacies on its mechanical properties and hence on the shale matrix. This work provides a novel methodology for constructing kerogen structures with different microscale properties that will be useful for delineating fundamental characteristics such as mechanical properties. The findings of this work can be used in a larger scale model for a better description of shale’s geomechanics.

Turbidite Fasies of Lower Penosogan Formation in Karanggayam Area, Kebumen, Indonesia

A continuous clastic sedimentary rock outcrop in the Karanggayam Area, Kebumen represents the complete deep marine fan facies of the Middle Miocene Lower Penosogan Formation. Lithology association and vertical succession were observed from a 63 meters detailed measured section along the Karanggayam River. This study aims to identify and classify the turbidite succession as well as the depositional environment of the formation within the North Serayu Basin, Central Java. From the bottom to top the Lower Penosogan Formation is divided into: A2, B2, C2, D2 and F2 facies which represents basin plain, overbank (levee and distal levee), crevasse splay, channel-fill and frontal splay facies respectively. Changes in the depositional environment are interpreted to be influenced by the dynamic changes in morphology and global climate change caused by underwater volcanic activity as a result of Middle Miocene tectonic activity.

Research On Petrophysical Properties Of Chosen Samples From The Point Of View Of Possible CO2 Sequestration / Výzkum Kolektorských Vlastností Vybraných Horninových Vzorků Z Hlediska Možné Geosekvestrace CO2

Man-made CO2 emissions (the so called anthropogenic CO2 emissions) and their increasing trend can be, by some scientists, considered a serious menace for the sustainable development of mankind, and their reduction a prerequisite for the environment protection. Carbon dioxide is one of the most important gases that cause a greenhouse effect which warms up the earth surface as a consequence of a different heat flow between the earth and the atmosphere. Our laboratory measurements determined the porosity, permeability and grain density for clastic sedimentary rock samples which were drilled from an underground gas storage facility. Additionally, our results showed a reduction in porosity and permeability after a confining pressure was applied. We assume that this effect is caused by internal structure changes due to the repeatedly increased and decreased net pressure applied to the samples

The Optimal Selecting Technique on Well Logging Items and its Application to Identify Complex Lithology Profile

Finding out the parameters with strong reflecting ability to construct recognition function can improve effectively identifying precision on complicatesets of geophysics data. Based on building the evenness parameter among individuals in one set and distance parameter between two sets, we perform optimal choice on well logging items of four lithology sets named as general sedimentary rock set, volcano-clastic rock set, volcano-clastic sedimentary rock set, lava set in Hailaer Base. By using optimal selected items into model clustering technique, the precision of the lithology identification is more than 85%.