Case studies can be instructive in the evaluation of other coalbed methane (CBM) development opportunities. The San Juan basin, located in New Mexico and Colorado in the southwestern U.S. (Figure 1), is the most prolific CBM basin in the world. It produces more than 2.5 Bscf/D from coals of the Cretaceous Fruitland formation, which is estimated to contain 43 to 49 Tscf of CBM in place. In the 1970s, after years of encountering gas kicks in these coals, operators recognized that the coal seams themselves were capable of commercial gas rates. CBM development benefited greatly from drilling and log data compiled from previous wells targeting the deeper sandstones and an extensive pipeline infrastructure that was built to transport conventional gas. These components, along with a U.S. federal tax credit and the development of new technologies such as openhole-cavity completions, fueled a drilling boom that resulted in more than 3,000 producing CBM wells by the end of 1992. The thickest Fruitland coals occur in a northwest/southeast trending belt located in the northeastern third of the basin. Total coal thickness in this belt locally exceeds 100 ft and individual coal seams can be more than 30 ft thick. The coals originated in peat swamps located landward (southwest) of northwest/southeast trending shoreline sandstones of the underlying Pictured Cliffs formation. The location of the thickest coals (Figure 1) coincides with the occurrence of overpressuring, high gas content, high coal rank, and high permeabilities in the San Juan fairway ("fairway"). The overpressuring is artesian in origin and is caused by water recharge of the coals through outcrops along the northern margin of the basin. This generates high vertical pressure gradients, ranging from 0.44 to 0.63 psi/ft, which allow a large amount of gas to be sorbed to the coal. Coal gas in the San Juan basin can contain up to 9.4% CO2 and 13.5% C2 . Chemical analyses suggest that thermogenic gases have been augmented by migrated thermogenic and secondary biogenic gas sources, resulting in gas contents ranging up to 700 ft 3 /ton. Coal rank in the fairway ranges from medium- to low-volatile bituminous and roughly coincides with those portions of the basin that were most deeply buried. Southwest of the fairway, Fruitland coals are typically 20 to 40 ft thick and are considerably underpressured with vertical pressure gradients in some areas of less than 0.20 psi/ft. The low gradients are attributable to low permeabilities, low recharge rates along the southern rim of the basin, and hydraulic isolation from the fairway area.
In this paper, we present for the first time, a classification system for naturally-occurring gas hydrate deposits existing in the permafrost and marine environment. This classification is relatively simple but highlights the salient features of a gas hydrate deposit which are important for their exploration and production such as location, porosity system, gas origin and migration path. We then show how this classification can be used to describe eight well-studied gas hydrate deposits in permafrost and marine environment. Potential implications of this classification are also discussed.
Grishankov, Vyacheslav (Halliburton) | Galimkhanov, Aydar (Halliburton) | Bogdanov, Sergey (Halliburton) | Kharitonov, Andrey (Halliburton) | Tikhonov, Evgeny (Halliburton) | Khalilov, Almaz (Halliburton) | Berezin, Alexander (Halliburton) | Dubrovsky, Maxim (Halliburton) | Tsibulsky, Mikhail (Halliburton) | Suvorov, Anton (RN-Shelf-Arktika OOO) | Netichuk, Igor (RN-Shelf-Arktika OOO)
This document describes the integrated engineering approach and technical solution used to perform a construction project of the first wildcat well in Khatanga subsoil area of the Laptev Sea.
Because of the small scope of performed geological exploration works and the absence of any previously drilled wells within the target area, a low degree of geological knowledge existed for this project. The unique location of the license area eventually complicated the profile of the Centralno-Olginskaya 1PO wildcat well and the logistics on the peninsula, consequently affecting the planning and performance of the project.
In these conditions, RN-Shelf-Arktika OOO and Halliburton encountered a range of challenging tasks associated with high quality planning and safe performance of the expected work scope within the planned timeframes. Other challenges encountered included fulfilling all geological tasks required to reduce expenses and developing technological and organization solutions for the subsequent construction of wells and the discovery of a new oilfield in the Eastern Arctic.
Because of the low level of geological knowledge about the territory, the operator regularly assigned new geological tasks. These changes eventually resulted in a longer wellbore (5530 m, rather than 4200 m), increased scope of geological activities (a longer coring interval of 156 m, rather than 90 m), and well design changes (five casing strings, rather than four).
To ensure the fulfillment of the required tasks, the completion of the project was based on an integrated approach for the integrity of the proposed technological and organization solutions, high quality of planning, and risk management and application of advanced technologies. This approach ensured 100% fulfillment of the geological objectives within the established timeframes and helped to develop a map of lessons learned with recommendations to optimize time and costs in the construction of future wells at the new field. Because of the project remoteness and challenging climate conditions, the well construction cost is the key factor for efficient field development (
The sewage dispersion in the radial sand ridges in the southern Yellow Sea is simulated using a particle-based method based on a three-dimensional numerical model. Six source points, where different tidal currents dominate, are considered. The particles released in Huangshayang Trough, which is dominated by the rotational tidal current, show more diffusive characteristics than those released in Xiyang Trough, where the tidal current is bi-directional. The fraction of total wastewater that originated from different tidal troughs is calculated, which indicate that the source contributions to total wastewater content in Xiyang Trough are nonlocal.
The radial sand ridges (hereafter indicated as “RSRs”) over the Jiangsu Coast (Fig. 1), cover an area of more than 200 km from north to south and approximately 140 km from east to west. The RSRs consist of more than 70 sand ridges with various dimensions radiating from the Jianggang towards the open sea (Wang, 2012). Since was initially observed in the 1950s, this area has received extensive attentions for its complicated hydrodynamics and peculiar geomorphology (He, 1979). Several large-scale field surveys have been conducted in terms of the hydrology, geomorphic characteristics, coastal climate and so on (e.g., Ren, 1986; Wang, 2002; Zhang et al., 2012). On the other hand, various numerical models have also been developed and applied to study the hydrodynamics and sediment dynamics in the RSRs (Zhang et al., 1999; Zhu and Chang, 2001; Xing et al., 2012).
The tidal currents in the RSRs are dominated by two different tidal wave systems, which are determined by the land boundaries of China and Korean Peninsula. As the progressive tidal wave from the Pacific Ocean enter the Yellow Sea, part of the wave is reflected by Shandong Peninsula forming a rotational tidal wave system. This rotational tidal wave meets the following progressive tidal wave, resulting in the formation of an approximately stationary tidal wave. This stationary tidal wave converges to the central region of the RSRs leading to remarkably large tidal range and current speed (Zhang et al., 1999). Moreover, the tidal currents and the underwater topography both show significant regional differences between the southern and northern part of the RSRs, which is correspondent to the distribution of the two tidal wave systems (Xu et al., 2016).
Nor has it been the purpose of the discussion presented thus far to provide explicit formulas for predicting quantitatively the recoveries from specific reservoirs or for evaluating them as items for sale or purchase. It has been an aim of this work to provide an exposition of the physical principles underlying the behavior of oil reservoirs so as to permit an understanding of their performance when observed in practice and an anticipation of the broad features of their performance from the consideration of basic data gathered during their development.
Baltika, the world’s first oblique icebreaker designed to break ice sideways, left Murmansk on 20 March 2015 and headed to the Russian Arctic. The purpose of the three-week voyage to Kara Sea and the Gulf of Ob was to evaluate the vessel’s icebreaking performance and operational capability through extensive full-scale trials in challenging Arctic ice conditions. In the ice-free Barents Sea, the seakeeping characteristics of the asymmetric icebreaker hull were also evaluated in moderate seas.
Performance trials were carried out in three different ice thicknesses, ranging from 40 cm thick saline sea ice in the Kara Sea to up to 1.22 m thick hard low-saline ice outside the Sabetta LNG terminal in the Gulf of Ob. During these trials, Baltika exceeded her design icebreaking capability of 3 knots in 1 m thick ice in both ahead and astern directions. In addition, the oblique icebreaking mode was demonstrated for the first time, and the vessel performed beyond expectations.
While the main goal of the trial voyage was to confirm Baltika’s icebreaking capability, both the vessel’s crew and the designers gained considerable operational experience during the daily operations in the challenging ice conditions. After the best way to tackle obstacles such as ridged ice fields was discovered, Baltika was found out to be equivalent - sometimes even superior - to conventional icebreakers despite her lower propulsion power.
There have always been those who have doubted the feasibility of the oblique icebreaker concept. The extensive full-scale ice trials in the Russian Arctic have shown that Baltika, the first icebreaker with an asymmetric hull, could not only break ice sideways, but also sometimes out-perform conventional icebreakers in other operational situations as well. The concept is thus seen to hold potential for a number of missions such as escort and port icebreaking and in offshore projects.
The region of the radial sand ridges along Jiangsu coast is a realistic nonlinear system, which has the unique ridges-and-troughs morphology and convergent tidal current field. In such marine system, the assessment of water environmental capacity affected by pollutants should be built on the understanding of local transport patterns. The transport characteristics of pollutants originated from land areas were analyzed using dynamical system approaches based on Lagrangian particle-tracking technique. The differences due to the release location and release time of pollutants were analyzed, totally different pathways due to the temporal perturbation of velocity fields illustrate their dependency on initial tidal phases.
The environmental capacity of water body is related to many factors, among which the flow pattern decided by both the geomorphology and physical conditions is a significant one. Thus, understanding of the transport characteristics of pollutants carried by water parcels is the basis for quantitative assessment of water environmental capacity. Extensive research using Lagrangian particle-tracking techniques has been reported in pollution management study, such as the prediction of oil spilling flick movement (Olascoaga & Haller, 2012), the sewage diffusion modelling (Coulliette et al., 2007), water quality modelling of coastal bathing places (Schippmann et al., 2013) and the rest. This kind of techniques, which is conducted in the Lagrangian framework, provides a straightforward and efficient way to dive into the related subjects concerning environmental issues. Moreover, dynamical system approaches using Lagrangian particle-tracking techniques have became increasingly popular in applications to geophysical fluid problems in recent years. The recognizing of Lagrangian coherent structures (LCSs) is a general solution for defining and detecting regions with different manifolds in geophysical flows. These regions distinguish particles’ movement separated by such structures as transport barriers. What we need for extracting these underlying flow structures are velocity fields derived by different means, including satellite imagery, radar survey , ocean models and the like.
Davoli, Giancarlo (Eni Exploration and Production) | Boz, Alberto (Eni Exploration and Production) | Baruffini, Luca (Eni Exploration and Production) | Minervini, Matteo (Ieoc Production BV) | Zhemchuzhnikov, Vyacheslav G. (North Caspian Oil Development)
Outcrop analogues represent a strong help in the building of geological models for exploration and reservoir studies. In particular, whenever the detail of the available subsurface data set is inadequate to describe the complexity of the geological setting, the study of a proper outcrop analogue may help reducing considerably the structural and reservoir architecture uncertainties.
In September 2002, the Kalamkas 1 exploration well successfully tested a multi-layer sandstone reservoir in the north Caspian Sea, the reservoir being composed of a thick succession of interbedded sands and shales, Jurassic in age. Given the encouraging results of the exploration well, and in order to get a better understanding of stratigraphic succession in the offshore license area, Agip KCO (then JV Operator), with the collaboration of the Satpaev Institute of Geological Sciences of Almaty and the Sedimentological Department of Eni E&P Division, decided to carry out a geological field survey in the Karatau Mountain Belt. The Jurassic paralic exposures have been studied with the aim of building the geological model for the time equivalent Kalamkas reservoir. Stratigraphic, sedimentologic and structural data have been collected in order to frame the Karatau and the Kalamkas offshore strata within a common regional geological framework. At the same time, a detailed field work approach, integrated with high resolution satellite imagery and LIDAR data acquisition, allowed to obtain a semi-quantitative reservoir-scale model to be used for driving an early Kalamkas offshore reservoir modelling. This paper illustrates the summary of the field work done in 2004 and 2005 and the application of the results to an early phase of the Kalamkas project workflow.
Making an efficient and wise concept selection decision—quickly selecting the right project—is often of equal or greater importance than later design and execution tasks for determining project success. Value lost from a suboptimal concept selection decision or from a needlessly prolonged decision process is independent of value generation opportunities during design and execution, and cannot be recouped during later project phases. This paper presents decision framework and production forecasting processes that complement one another, and promote an efficient and high-quality concept selection decision for tight or unconventional resources. The method is for both oil and gas resources, and is especially useful for assessing and developing large contiguous tracts.
High quality production forecasting is very important during concept selection. Better quality concept selection decisions will also result if the alternative conceptual plans are equally optimized when the decision is made, and our assessment process facilitates both accurate forecasting and equal optimization of the various development alternatives. Our method includes symmetry element reservoir simulation models and an efficient economic spreadsheet model with an optimizer. The sector simulation models run fast and can evaluate many cases, but they still explicitly address the physical effects relevant to flow in porous media with vertical, transverse, hydraulic fractures intersecting horizontal wells. The decision framework is structured so that some decisions are independent of the simulation model, and those decisions are rapidly optimized within the economic model. We introduce a fracture efficiency factor which may be important for modeling the diminished performance observed as the number of stages increase in multi-fractured horizontal wells. This fracture efficiency factor may also be an important discriminator of performance between wells fractured using aqueous vs. non-aqueous fracturing fluids. We also show how to use meaningful constraints with a symmetry element model to ensure that the economic forecasts are both realistic and achievable.
The methods in this paper are applicable to tight and unconventional resource projects, which we lump together and refer to as UCRs. The authors' company uses a five-phase project management process similar to that now used by many other integrated oil and gas companies. In our company's process, project phase 2 is called "Concept Selection?? (Reynolds, Brennan, et al. 2004), and others call it Front-End Loading 2 (or FEL2). Part of wisely managing any project includes identifying the important decisions that will impact project value, and understanding when these decisions need to be made relative to each other. A common understanding of the decision framework among the project team and the decision makers is critical. The authors' company uses a tool called a Decision Hierarchy to identify and specify the sequence of the project decisions. A decision hierarchy includes three elements called "Givens??, "Focus Decisions,?? and "Tactics,?? which we refer to collectively in this paper as the decision framework. For any project phase, the givens are the decisions that have been made in a previous project phase, and the givens also include all the project assumptions. The "Focus Decisions?? are those being made during—and that will be locked down at the end of—the current project phase. Decisions which can be made and finalized during a later project phase are called "Tactics.?? The Discussion section of this paper includes a decision hierarchy illustration with our example assessment.
The oil field is now monitored and controlled 24 hours a day from any location throughout the world. But, it was not always like that. The rapid invasion of technology can be traced back to the US west coast. In San Francisco and the nearby area known as Silicon Valley, information technology (IT) developed from the idea stage into an industry that has changed the world. Can anyone conceive of a day at work without a computer and the Internet?