Embedment

About: Embedment is a research topic. Over the lifetime, 2441 publications have been published within this topic receiving 31444 citations.

Lateral and Upward Soil-Pipeline Interactions in Sand for Deep Embedment Conditions

Abstract: The soil–pipeline interactions in sand under lateral and upward movements are investigated with particular attention to the peak forces exerted on the pipe. The analytical solutions for estimating the peak forces are summarized and it is shown that, for deep embedment condition, there is large uncertainty in the true values since the bounds established by the analytical solutions are large. In order to find the solution for the peak force and to investigate its transition from shallow to deep failure mechanism, finite element analyses of lateral and upward pipe movements are performed for different embedment conditions. Two different soil models (Mohr–Coulomb and Nor–Sand models) are used for the simulations. The accuracy of the analysis is first examined by simulating experimental tank tests. The analysis is further extended to deeper embedment ratios of as large as 100. The obtained finite element results are used to construct a design chart for deep embedded pipelines.

Influence of rigidity on laterally loaded pile groups in marine clay

Abstract: Pile-supported marine structures are designed for significant amounts of lateral load. In this paper, the influence of parameters like flexural rigidity of pile material, embedment length of pile, and arrangement of piles with respect to the direction of loading on the behavior of laterally loaded pile groups has been studied through an experimental program. The results obtained from lateral load tests carried out on model pile groups arranged at different spacings and embedded in a marine clayey bed are presented and discussed. The results indicate that the lateral load capacity of the pile group depends mainly on the rigidity of pile soil system for different arrangements of piles within a group. This is further substantiated by a simplified finite element analysis bringing in the differences in passive resistance. The group efficiencies under lateral loading obtained from the present investigation are found to be in good agreement with the predictions of earlier researchers.

The Effects of Fracturing Fluids on Shale Rock Mechanical Properties and Proppant Embedment

Abstract: The development of shale reservoirs has grown significantly in the past few decades, spurred by evolving technologies in horizontal drilling and hydraulic fracturing. The productivity of shale reservoirs is highly dependent on the design of the hydraulic fracturing treatment. In order to successfully design the treatment, a good understanding of the shale mechanical properties is necessary. Some mechanical properties, such as Young’s modulus, can change after the rock has been exposed to the hydraulic fracturing fluids, causing weakening of the rock frame. The weakening of the rock has the potential to increase proppant embedment into the fracture face, resulting in reduced conductivity. This reduction in conductivity can, in turn, determine whether or not production of the reservoir will be economically feasible, as shale rocks are characterized by their ultra-low permeability, and conductivity between the reservoir and wellbore is critical. Thus, shale reservoirs are associated with economic risk; careful engineering practices; and a better understanding of how the mechanical properties of these rocks can change are crucial to reduce this risk. This paper discusses various laboratory tests conducted on shale samples from the Bakken, Barnett, Eagle Ford, and Haynesville formations in order to understand the changes in shale mechanical properties, as they are exposed to fracturing fluids, and how these changes can affect the proppant embedment process. Nanoindentation technology was used to determine changes of Young's modulus with the application of fracturing fluid over time and under high temperature (300 °F) as well as room temperature. Mineralogy, porosity, and total organic content were determined for the various samples to correlate them to any changes of mechanical properties. The last part of the experiments consisted of applying proppants to the shale samples under uniaxial stress and observing embedment using scanning acoustic microscope. The results of this study show that maximum reduction of Young’s modulus occurs under high temperature and in samples containing high carbonate contents. This reduction in Young’s modulus occurs in “soft” minerals as well as the “hard” rock-forming minerals. This reduction of modulus can cause the effective fracture conductivity to decrease significantly. Introduction In geology, shale has traditionally been defined as a sedimentary rock containing high percentages (more than 50%) of clays and lower percentages of silica or carbonate minerals (Britt and Schoeffler, 2009). However, many of the shale prospects that are currently being developed in the petroleum industry are not shales, as defined in geology. They are, instead, “prospective shale” reservoirs, which are fine-grained clastics that are characterized by their ultra low permeability and usually composed of silica and carbonate with a small amount of clay minerals (Britt and Schoeffler, 2009). Generally, shale rocks have been considered as source rocks for conventional oil and gas reservoirs. However, with technological evolution in the petroleum industry, such as hydraulic fracturing, the rising oil and gas prices, as well as the escalating demand for fossil fuels, these rocks are increasingly regarded as the source, the seal, and the reservoir. Subsequently, development of such reservoirs is becoming more and more technically and economically feasible. The reasons behind the success of these shale systems are largely dependent on excellent hydraulic fracturing designs that require a good understanding of the mechanical properties of the subject and confining formations. In hydraulic fracturing design, Young's modulus is one criterion used to define the most appropriate fracturing fluid and other design considerations. Young's modulus provides an indication of how much fracture conductivity, kfw, can be expected due to width and embedment considerations. Without adequate fracture conductivity, production from the hydraulic fracture will be minimized if not completely eliminated. This paper discusses conditions where Young’s modulus is shown to decrease