Fracture-Related Diagenesis May Impact Conductivity

SPE Journal ◽  
2007 ◽  
Vol 12 (03) ◽  
pp. 272-281 ◽  
Author(s):  
Jim Dean Weaver ◽  
Mark Parker ◽  
Diederik W. van Batenburg ◽  
Philip Duke Nguyen

Summary Rapid loss of fracture conductivity after hydraulic fracture stimulation has often been attributed to the migration of formation fines into the proppant pack or the generation of fines derived from proppant crushing. Generation of crystalline and amorphous porosity-filling minerals can occur within the proppant pack because of chemical compositional differences between the proppant and the formation, and the compaction of the proppant bed because of proppant pressure solution reactions. Findings presented in this paper suggest that diagenesis-type reactions that can occur between proppant and freshly fractured rock surfaces can lead to rapid loss of proppant-pack porosity and loss of conductivity. Introduction Lehman et al. (2003) reported that the use of surface-modification agents (SMA) to coat proppants used in propping hydraulic fractures resulted in sustained and more uniform production from wells. Fig. 1, taken from that publication, shows the production decline curves from some of their data, and it does appear to show a significant change in decline rate compared to the use of untreated proppant. This SMA was described as a nonhardening resin that is insoluble in water and oil. It is supplied in a solvent that is quickly extracted once it is introduced to aqueous-based frac fluids, leaving a tacky, hydrophobic coating on the proppant. Initial use of this type of SMA treatment (Dewprashad et al. 1999; Nguyen et al. 1998a, b) was promoted as a method to increase the conductivity of proppant owing to its capability to prevent close packing of the proppant, which can result in increased porosity and permeability of the pack, by rendering the proppant surface tacky. Subsequent studies indicated that its use provided proppant-pack protection from fines infiltration and migration. This mechanism has been employed to explain the observations that sustained production results from the use of SMA on proppants. This is further substantiated by long-term results obtained in a single field study known for fines production problems. That both mechanisms are active has been well established through laboratory studies, but they alone do not completely explain the reduction in production decline rate as reported. A field study of SMA-treated proppant was reported to the Arkansas Oil and Gas Commission 2004 CBM Workshop that disclosed long-term results on gas production. These were CBM wells in the San Juan basin that typically required refracturing each year to produce at an economical rate. With the SMA-treated proppant, no refracs have been required, and as shown in Fig. 2, production has remained essentially constant for 5 to 6 years. This longevity was initially attributed to prevention of fines invasion into the proppant pack; however, it is possible that there are additional mechanisms operational.

Author(s):  
Josef Flatlandsmo ◽  
Torbjørn Smith ◽  
Ørjan O. Halvorsen ◽  
Johnny Vinje ◽  
Thomas J. Impelluso

Norwegian industries are constantly assessing new technologies and methods for more efficient and safer production in the aqua cultural, renewable energy, and oil and gas industries. These Norwegian offshore industries share a common challenge: to install new equipment and transport personnel in a safe and controllable way between ships, farms and platforms. This paper deploys the Moving Frame Method (MFM) to analyze the motion induced by a crane and controlled by a gyroscopic inertial device mounted on a ship. The crane is a simple two-link system that transfers produce and equipment to and from barges. An inertial flywheel — a gyroscope — is used to stabilize the barge during transfer. The MFM describes the dynamics of the system using modern mathematics. Lie group theory and Cartan’s moving frames are the foundation of this new approach to engineering dynamics. This, together with a restriction on the variation of the angular velocity used in Hamilton’s principle, enables an effective way of extracting the equations of motion. This project extends previous work. It accounts for the dual effect of both the crane and the stabilizing inertial device. Furthermore, this work allows for buoyancy and motor induced torques. Furthermore, this work displays the results in 3D on cell phones. The long-term results of this work leads to a robust 3D active compensation method for loading/unloading operations offshore. Finally, the interactivity between the crane and the stabilizing gyro anticipates the impending time of artificial intelligence when machines, equipped with on-board CPU’s and IP addresses, are empowered with learning modules to conduct their operations.


1989 ◽  
Vol 16 (1) ◽  
pp. 72-81 ◽  
Author(s):  
Brahim Benmokrane ◽  
Gérard Ballivy

Estimation of loss of prestress is an essential part of the design of permanent or temporary prstressed anchors since stability of the retained structure must not be compromised. Findings of a field study on long-term behaviour of prestressed anchors are presented herein: different lengths of anchors in solid rock were injected with cement grout or epoxy resin. Load variation in the anchors with time indicated two distinct stages of loss of prestress: an initial stage of rapid loss of prestress and a second stage of very minor and uniform loss ending about 6 months after prestressing. Our study also showed that restressing anchors after a period of time reduces subsequent prestress loss and that overdimensioning of the injected length does not. Key words: rock, prestressed injected anchor, grout, loss of prestress, creep, relaxation.


2015 ◽  
Vol 55 (2) ◽  
pp. 425
Author(s):  
Camis Smith

Advancing Aboriginal participation in the workplace comes with its challenges, and those experienced in the oil and gas industry are unique. Barriers to participation need to be regularly evaluated and addressed for success. Although Chevron Australia's focus on Aboriginal employment is fairly recent, it receives strong internal support from senior and corporate leadership. It will be important in the future to further this commitment and build ownership throughout the organisation to achieve long-term results and meet business needs and skills gaps. Camis Smith, Chevron Australia's Aboriginal Employment Strategy Manager, will share Chevron's experiences, lessons and challenges in advancing Aboriginal participation in the workplace, and reinforce its reputation as an employer of choice. Chevron is one of the world's leading integrated energy companies and through its Australian subsidiaries, has been present in Australia for more than 60 years. With the ingenuity and commitment of more than 4,000 people, Chevron Australia leads the development of the Gorgon and Wheatstone natural gas projects, and has been operating Australia's largest onshore oilfield on Barrow Island for more than 45 years.


2019 ◽  
Vol 10 (4) ◽  
pp. 1613-1634 ◽  
Author(s):  
Oladoyin Kolawole ◽  
Ion Ispas

Abstract Hydraulic fracturing treatment is one of the most efficient conventional matrix stimulation techniques currently utilized in the petroleum industry. However, due to the spatiotemporal complex nature of fracture propagation in a naturally- and often times systematically fractured media, the influence of natural fractures (NF) and in situ stresses on hydraulic fracture (HF) initiation and propagation within a reservoir during the hydrofracturing process remains an important issue. Over the past 50 years of advances in the understanding of HF–NF interactions, no comprehensive revision of the state of the knowledge exists. Here, we reviewed over 140 scientific articles on investigations of HF–NF interactions, published over the past 50 years. We highlight the most commonly observed HF–NF interactions and their implications for unconventional oil and gas production. Using observational and quantitative analyses, we find that numerical modeling and simulation is the most prominent method of approach, whereas there are less publications on the experimental approach, and analytical method is the least utilized approach. Further, we suggest how HF–NF interactions can be monitored in real time on the field during a pre-frac test. Lastly, based on the results of our literature review, we recommend promising areas of investigation that may provide more profound insights into HF–NF interactions in such a way that can be directly applied to the optimization of fracture-stimulation field operations.


Author(s):  
Shankar Sundararaman ◽  
Mark Cerkovnik ◽  
Luiza Ferreira ◽  
Phil Ward

Drilling and intervention risers are widely used for oil and gas production in deep as well as shallow waters in oil fields around the world for subsea operations. The risers come in a diverse array of configurations, some of which may be challenged by fatigue if operated in high currents or seastates. The suitability of the selected riser and the operating limits are assessed by conducting strength and fatigue analysis based on design codes such as API RP 2RD, [7], API RP 16Q, [9], and API RP 17G, [10]. Typically, drilling and intervention activities are conducted for short periods of time but used repetitively. The codes are clear about the return period of the design environmental event which must be checked to insure safe operation with respect to strength; however, assessment of fatigue integrity can be more difficult to determine. The allowable fatigue operating environment should account for the ability to disengage, the time required to disengage, the damage rates in particular seastates, prior accumulation of fatigue damage, and variations in soil, tension and internal fluid weights. In this paper, an orderly method of establishing the allowable fatigue operation limits for drilling and intervention risers is presented based on Monte Carlo simulations along with a case study implementing the methodology in a shallow water environment. To illustrate this concept, a riser with wellhead and conductor system is assessed and is subjected to directional loading from several long-term seastates. The variation in effects is studied by doing fatigue analysis for different durations: 3 days, 1 week, 3 months, 1 year and 10,000 hours.


Subject Prospects for the hydrocarbons sector under the new government Significance After three years of GDP contraction, a new government is pursuing increased foreign investment in hydrocarbons, to boost employment and growth and to repair the budget. In the long term, Greenland is likely to emerge as an international shipping, mining and hydrocarbons centre. For now, the fall in the international oil price has seen oil exploration stop. The wish for economic development is leading a new generation of Greenlandic politicians to embark on re-integration with the EU, where a ban on seal products is the greatest obstacle to closer ties. Impacts Infrastructure and climate challenges mean that full-scale oil and gas production is at least 15-20 years away. Emerging Greenland-China economic ties may create a new alignment in the opening up of the Arctic. A relaxation of the EU seal products ban would ease negotiations on Greenland's further integration with the bloc. Enhanced EU-Greenland ties could extend the EU's role in the Arctic.


Subject The outlook for the LNG market. Significance With major oil and gas reserves, and around 5% of global GDP, South America might in theory be expected to play an important role in the global liquefied natural gas (LNG) business. It both produces and consumes LNG, but the factors affecting LNG production and consumption are national and global rather than primarily regional. In global terms, the region is neither a major producer nor a large market. Impacts With no new LNG production or export facilities currently announced, the region will not become a major producer soon. The Panama Canal will play a key role in facilitating LNG trade around the region and globally. For countries lacking material gas production, for example Chile, LNG will continue to be a key energy source. Growing gas production in Brazil and Argentina over the medium to long term may increasingly relegate LNG consumption.


2019 ◽  
Vol 59 (3) ◽  
Author(s):  
Nathan Fay

This year marks the golden jubilee of Australia’s offshore petroleum industry after the first gas was produced from Bass Strait by Esso and BHP’s Gippsland Basin Joint Venture. For half a century our industry has been driven by technology – pioneering technical excellence and pushing the envelope in the pursuit of much needed oil and gas production. Today, the landscape in East Australia is changing and gas is at the forefront of the discussion. Declines in East Australia’s historical conventional fields have seen gas supply tighten and prices rise. There is a strong need for additional affordable and reliable gas supply. While continued improvements in technology remain a critically important enabler in developing Australia’s gas resources; global supply and demand, regulatory frameworks, and the commercial arrangements that underpin new developments are becoming more and more important. ExxonMobil Australia’s new Chairman, Nathan Fay, has a wealth of experience working with gas markets around the world. He will explain why it is so important for policymakers to establishment a stable free market environment to encourage these long-term relationships. To view the video, click the link on the right.


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