The drilling conditions described above have led to the following practices, which are reasonably uniform, in the geothermal drilling industry. Bits Because of the hard, fractured formations, roller-cone bits with tungsten-carbide inserts are almost universally used for geothermal drilling. The abrasive rocks mean that bit life is usually low (50 to 100 m), but many bits are also pulled because of bearing failures caused by rough drilling and high temperature. Much research and development in hard-rock PDC bits is under way,  so it is possible that these bits will come into wider use in geothermal drilling. Tubulars Because of the low-value fluid (steam or hot water), geothermal wells must produce large fluid volumes and so tend to be larger diameter than oil/gas wells; typical geothermal production intervals are 219 to 340 mm in diameter.
Tracers are used in geothermal reservoir engineering to determine the connectivity between injection and production wells. Because injected fluids are much cooler than in-situ fluids, knowledge of injectate flow paths helps mitigate premature thermal breakthrough. As in other applications of tracer testing, the goal of the tracer test is to estimate sweep efficiency of a given injection pattern. Because geothermal systems tend to be open, tracer tests can also be used to estimate the extent of recharge/discharge or total pore volume. Currently, however, the primary use of geothermal tracers is to estimate the degree of connectivity between injectors and producers.
With the purpose of studying Chinese mainland shallow crustal stress state, we have built a spherical shell finite element model including main active faults, tectonic blocks, topography, and Moho discontinuity with the consideration of lithospheric heterogeneity. In this model, we deem gravity and plate tectonic stress as the main influential factors, and use the in-situ stress as the main constraints to make the simulation results and in-situ stress measurement comparable. By this way, we obtain the absolute value estimations of China mainland stress field.
Numerical results are: (1) the general directions of maximum horizontal stress are distributed radially with the center of Tibetan Plateau. From east to west, the directions of maximum horizontal stress gradually rotate clockwise from NS to NNE, NE, NEE, SE, consistent with previous results of focal mechanism solution; (2) the stress states in different study regions vary greatly. Stress is obviously lower in the center of Qinghai-Tibet active block and higher in its surrounding areas; (3) the maximum and minimum tectonic stress σΗ and σh are mainly compressive at the depth of 2000 meters in the shallow crust of Chinese mainland, and the magnitude range are 14.5MPa < σΗ <58.0MPa and 3.8MPa < σh <26.7MPa respectively.
The in-situ stress measurement method is a primary means to understand the present-day state of stress, but due to the measurement restriction, we can only measure the shallow crust stress state. How to take advantage of various known data to analyze the regional crustal stress state quantitatively is a complex problem involving geology, mechanics, mathematics and many other disciplines. The formation of tectonic stress field is determined by many factors such as tectonic movements, geological lithology, topography, rock weight, etc. In-situ stress is the result of the combined effects of these factors. Based on the measured data of stress, the deduction of stress in non-measured region can be regarded as a process of simulating the effects of these factors. In this paper, finite element method is applied to calculate the absolute stress of the shallow crust in China. The fundamental concept of our research is following: (1) Establish our finite element model with the consideration of previous studies concerning geology, geophysics, rock mechanics, etc.; (2) Use gravitational field as the initial field and apply horizontal boundary loading based on results of previous related researches; (3) Adjust physical parameters and boundary conditions to make the simulated shell surface stress directions and value close to the in-situ stress measurement results as possible, and eventually obtain the current Chinese land shallow stress field.
Asia is the largest and the most populous continent in the world covering an area of 44,579,000 sq. Its 4.5 billion people form roughly 60% of the world's population. To understand the intricacies of this vast and diverse continent, it is a common practice to categorize the constituting countries as per the subject--economic development--under discussion. One such categorization is "Tiger Economies." It is the nickname given to the economies of Southeast Asia. The tigers are South Korea, Taiwan, Hong Kong, and Singapore.
Asia is the largest and the most populous continent in the world covering an area of 44,579,000 sq. Its 4.5 billion people form roughly 60% of the world's population. To understand the intricacies of this vast and diverse continent, it is a common practice to categorize the constituting countries as per the subject—economic development—under discussion. One such categorization is “Tiger Economies.” It is the nickname given to the economies of Southeast Asia. The tigers are South Korea, Taiwan, Hong Kong, and Singapore.
For more than 50 years, coiled tubing (CT) has been an intervention technology used primarily to maintain or increase production. In the last 10 years, CT telemetry systems have been used for such applications as milling, stimulation, well cleanouts, gas lifting, camera services, logging, and perforating. These systems have resulted in increased certainty, improved safety and efficiency, and reduced time and cost. In this article, a review of a CT telemetry system with 0.125-in. tube wire, including the technology development and field applications, is presented for the first time. Unlike conventional CT for which surface-measured parameters, such as CT weight and length and pumping pressure, are the only parameters available to monitor the operation’s progress, CT telemetry systems provide real-time monitoring of downhole data such as pressure, temperature, depth, and others. The CT telemetry system described in this article consists of the surface hardware and software, a 0.125-in. tube wire inside the CT connecting the surface equipment and the downhole tools and sensors, and a versatile bottomhole assembly (BHA), designed in three sizes (i.e., 2.125-, 2.875-, and 3.5-in.). The 0.125-in. tube wire has the dual purpose of powering the downhole sensors and transferring the real-time downhole data to the surface. The sensors available are a casing-collar locator (CCL), two pressure and temperature transducers (capable of measuring downhole data inside and outside the BHA), and tension, compression, and torque gauges. In addition, cameras with front and lateral views and flow-through capabilities could be used. One of the advantages of this CT telemetry system is its versatility: Switching between applications is as simple as changing parts of the BHA, significantly reducing the operational time and cost, and increasing safety. Another advantage stems from the acquisition of real-time downhole data, enabling the CT field crew to intervene promptly on the basis of dynamic downhole events. A state-of-the-technology review of the 0.125-in. tube-wire CT telemetry system is presented for the first time. The many benefits of the real-time monitoring of the downhole parameters during such CT applications are summarized. These applications include logging, zonal isolation, collapsed-casing identification, scale removal, cleanout and perforation, milling, confirmation of jar activation during fishing jobs, and others. Many of these applications were performed together, and the real-time monitoring of downhole data increased the job efficiency, control, and safety, and reduced the operational costs by simplifying the operational procedures and equipment.
Geohazards affecting offshore facilities are typically mitigated through avoidance. However, as stated by
If present, seismically induced geohazards (e.g., seabed settling due to liquefaction) can be mitigated by placing facilities on deep foundations that penetrate through liquefiable layers. Alternatively, facilities can be placed on shallow foundations that are designed to tolerate permanent ground displacements. These ground displacements depend on various factors such as the density and thickness of the liquefiable layer, the depth to the liquefiable layer, and characteristics of the ground motion (e.g., intensity, magnitude, and duration). The magnitude of settlement that needs to be incorporated in design must be based on either a deterministically developed design earthquake scenario or a probabilistically developed annual probability of exceedance (or return period).
This paper describes how hazard curves can be calculated to estimate liquefaction-induced settlement under shallow foundations overlying liquefiable soils. These hazard curves were developed using the PEER performance-based earthquake engineering (PBEE) framework (Deierlein et al., 2003). The PBEE framework incorporates the probability of seismically induced ground motions developed from a probabilistic seismic hazard analysis (PSHA), the probability of liquefaction conditioned to the occurrence of a ground motion, and the probability of settlement conditioned to the occurrence of liquefaction. The results of the analyses are discussed, and recommendations are made for incorporation in evaluation of geohazard and designs considering their occurrence.
For more than 50 years, coiled tubing (CT) has been an intervention technology primarily used to maintain or increase production. In the last 10 years, CT telemetry systems have been used for such applications as milling, stimulation, well cleanouts, gas lifting, camera services, logging and perforating, increasing certainty, improving safety and efficiency, and reducing time and cost. In this paper, a review of a CT telemetry system with 2 ⅛-in. tube wire, including the technology development and field application, is presented for the first time.
Unlike conventional CT for which surface-measured parameters, such as CT weight and length and pumping pressure, are the only parameters available to monitor the operation's progress, CT telemetry systems provide real-time monitoring of downhole data such as pressure, temperature, depth, etc. The CT telemetry system described in this paper consists of the surface hardware and software, a 2 ⅛-in. tube wire inside the CT connecting the surface equipment and the downhole tools and sensors, and a versatile bottomhole assembly, designed in three sizes (i.e., 2 ⅛-, 2 ⅞-, and 3 ½-in.). The 2 ⅛-in. tube wire has the dual purpose to power up the downhole sensors and to transfer the real-time downhole data to surface. The sensors available are a casing collar locator (CCL), two pressure and temperature transducers (capable to measure downhole data inside and outside of the tool), and tension, compression, and torque gauges. In addition, cameras with front and lateral views and flow-through capabilities could be used. One of the advantages of this CT telemetry system is its versatility: switching between applications is as simple as only changing parts of the bottomhole assembly, significantly reducing the operational time and cost and increasing safety. Another advantage stems from the downhole data certainty in real time, as the CT field crew can promptly intervene based on dynamic downhole events.
A state-of-the-technology review of the 2 ⅛-in. tube wire CT telemetry system is presented for the first time. The many benefits of the real-time monitoring of the downhole parameters during such CT applications as logging, zonal isolation, collapsed casing identification, scale removal, cleanout and perforation, milling, confirmation of jar activation during fishing jobs, etc., are also summarized. Many of these applications were performed together and the real-time monitoring of downhole data increased the job efficiency, control and safety and reduced the operational costs by simplifying the operational procedures and equipment.
The paper summarizes the results stemming from 10 years of global experience with the 2 ⅛-in. tube wire CT telemetry system. A new case history involving the 2 ⅛-in. tube wire CT telemetry system and a vibratory tool is presented for the first time. As currently there is a strong inertia to automate the drilling operations, all details presented in this paper show that the CT telemetry systems are poised to become standard technologies for all CT operations in the not-so-distant future.
Frankenmolen, Sebastiaan (Shell Global Solutions) | Ang, Sze-Yu (Shell Global Solutions) | Peek, Ralf (Peek Solutions) | Carr, Malcolm (Crondall Energy) | MacRae, Ian (Crondall Energy) | White, David (University of Western Australia) | Rimmer, Jeffrey (Shell Philippines Exploration and Production)
AbstractThermal gradients from a heating front travelling down a flowline at start-up can cause a flowline to walk much like a worm creeps by repeated contractions and expansions of its body. To stop this for the Malampaya flowline, pipe-clamping mattresses (PCMs) were invented, developed, and deployed within a period of 12 months. The objective of this paper is to share the knowledge and experience from this novel but effective solution to mitigate pipeline walking.PCMs provide a cost-effective alternative to rockdump or conventional mattresses to axially restrain a pipeline at a location chosen so that the required restraint capacity is minimized. They are inspired by conventional mattresses and bear some similarity to them, but they are designed so that the weight of the mattress acts to clamp the pipeline with a high leverage. Thus 100% of the weight of the mattress is effective in generating axial friction with the seabed. This solution can be applied at any point along the line (chosen to minimize the required resistance) without requiring flanges or collars on the pipeline.From the most recent survey results 15 PCMs with a dry weight of around 9 tons per PCM, plus 7 tons for the logmat installed over every PCM appear to be effective to stop the walking of the Malampaya flowline. This performance is as expected from extensive analysis (FE and otherwise) to reproduce the observed walking behavior prior to restraining, to estimate the required restraint capacity, and to estimate the resistance provided by the PCMs.This paper describes the PCM, the clamping forces they generate by leveraging the weight of the PCM and logmats installed over them, and how the friction generated with the soil is estimated from interface shear tests on samples collected from the site, considering cyclic pore pressure generation and dissipation effects. It also briefly covers FE analyses to reproduce the observed walking behavior, and determine the required restraint capacity, the PCM fabrication, installation, and monitoring of the post-installation performance.
Legislation worldwide is aiming at a good balance between environmental protection and capital expenditure on water treatment systems. There is a clear trend to move from integral discharge parameters like BOD, COD and Dispersed Oil to more focused approaches aiming at Zero Harmful Discharge. The leading management tools are the Environmental Impact Factor from Norway and the Risk Based Approach being developed by OSPAR. Here the Toxic and Nontoxic contents are recognized. This has led to new water treatment technologies using other separation mechanisms than gravity/coalescence to achieve Zero Harmful Discharge. The Macro Porous Polymer Extraction (MPPE) technology uses liquid-liquid extraction to remove dispersed and dissolved toxic constituents. A real life experience on the disastrous effect of unknown toxic content on the bio treatment confirming the Environmental Impact Factor model will be presented. MPPE treats Offshore produced water since 1994 with a 99% removal performance of dissolved and dispersed Oil, BTEX, Poly Cyclic Hydrocarbons (PAHs) and other non-polar toxic constituents. Examples of applications in the North Sea, Europe (TOTAL, Statoil, Shell) and Australia (Woodside PLUTO, Shell FLNG PRELUDE, Inpex ICHTHYS) will be presented. The trend of aiming at Zero Harmful Discharge is supported by future projects in other Geo areas and other markets like shale oil. Finally benchmark studies on current MPPE units show a structural Mercury removal that is being further investigated.