bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ABUNDANCE OF KARST-RIPARIAN FOREST IN THE CATCHMENT AREA OF SAMPOLAWA RIVER BAUBAU, SOUTHEAST SULAWESI
Authors: Erif La Ode Muhammad , Djohan Tjut Sugandawaty
Published: September 2015

Riparian forest is a source energy and matter for the aquatic ecosystem. The abilities of riparian forest are to control and recycle the allochthonous inputs from the upland drainage basin and the river itself. This processess are a fundamental aspect of river ecology. We studied the riparian forest in karst ecosystem setting, at the protected forest of Sampolawa headwaters river, Baubau, Southeast Sulawesi. We focussed on the structure and composition of species richness of the forest. Data were collected using quadrate methods, 20mx20m, with 4 replicates placed at each river side. Results reveal that the forest compossed of 7 growth-forms, trees, saplings, seedlings, palm, herbs, liana, and spike moss. The tree species richness of tree and sapling was 33 and 37 species in consecutively. The tree species of Sphatolobus sp., Aglaia silvestris, and Canarium asperum dominated this riparian forest. Similarly the sapling dominance were Sphatolobus sp., Aglaia sp., and Chrysophyllum lanceolatum, as well as the seedlings of Sphatolobus sp., Palaquium obovatum and Chrysophyllum lanceolatum. Thus, the Sphatolobus sp. will be the future tree. However, Anthocephalus macrophyllus saplings were not found, thus this tree was endangered. Soil nutrients of NO3, NH4, PO4, and C organic were high, which indicated that the litterfall decomposition occurred at the forest riparian floor. The Riparian forest was a primary forest and very diversed in species richnes but had low densities. All the tree, sapling, and seedling species characterized the riparian forest of karst ecosystem at the headwaters of Sampolawa River in the karst ecosystem setting.

Keywords: Anthocephalus, karst-riparian forest, headwaters
LEOPARD (Panthera pardus L.) IN PURWODADI, TEPUS, GUNUNGKIDUL, YOGYAKARTA, INDONESIA
Authors: Atmaja Edi Dwi , Dwisetiyani Budi
Published: September 2015

Indonesia is a beautiful archipelago country. It has many habitat type and ecosystem. The most interesting area is karst. By its special characteristics like high concentration of calcium (Ca), makes karst area has a specific and uniquely ecosystem. Gunungsewu is the largest karst area in Indonesia. The surface ecosystem of karst (eksokarst) in Indonesia is very dry, however we can find Leopard (Panthera pardus L), especially in Southern part of Karst Gunungsewu. That is why we are interested to study about it. In this study, we use observation and interview method. From the temporally result (research still on progress), we know that in Purwodadi, Tepus area live two sub-species of Leopards, those are Spotted Leopard (Panthera pardus pardus) and Javanese Black Leopard (Panthera pardus melas) with porcupine (Hystrix javanica), squirrel (Caloscurus notatus), Mongoose (Paradoxurus hermaphroditus), and other small mammals and some birds as their prey. In some cases, we find Leopard eats the dead human body but they rarely eat cattle although it takes in the middle of the farms. The habitat of Leopard was fragmented. Now they only life in five fragmented part of karst Gunungsewu and their habitat degrade slowly from year to year. From the results, we can conclude that conservation in Karst of Gunungsewu especially in Purwodadi, Tepus, Gunungkidul is badly needed. It must be done soon because Leopard becomes extinct. We can use local wisdom to conserve it because it has proven can make a good interaction between human and Leopards in their habitat.

Keyword: predator, tropical, karst, Gunungsewu

 
THE EFFECTS OF GAMMA IRRADIATION AND SOMACLONAL VARIATION ON MORPHOLOGY VARIATION OF MUTANT RODENT TUBER (Typhonium flagelliforme Lodd.) LINES
Authors: Sianipar Nesti F. , Purnamaningsih Ragapadmi , Darwati Ireng , Laurent Danny , . Chelen
Published: September 2015

Rodent tuber (Typhonium flagelliforme Lodd.) is an Indonesian plant with high medicinal potential as anti-cancer. This plant has a low genetic variation in Indonesia. Gamma irradiation can be used to increase genetic variation. This research aimed to explore the effects of gamma irradiation and somaclonal variation on several mutant rodent tuber lines. Six somatic cell populations, which were treated by 6 Gy of gamma irradiation, were successfully regenerated into plantlets. Six mutant lines had been sub cultured into second and third generations by using optimal regeneration media (MS0 supplemented with 0.5 mg/L BAP and 1 mg/L NAA). Rooting of in vitro plantlets had been done by using optimal rooting media MS0 supplemented with 0 mg/L NAA and 0.5 mg/L NAA). Plantlets with good roots were acclimatized and transferred into greenhouse. The morphology of first generation mutant in greenhouse (M1) were characterized and analyzed by using descriptive statistical method. The observed morphological characters including plant height, shoot number, leaf number, and leaf area. A hundred and seventy five (175) mutant lines were obtained on the third generation (MV3) from five somatic cell populations. Mutant line 6-3-x has the highest mean number of shoots, which was 4.62 shoots. Percentage of plant alive after acclimatization in the greenhouse was 78%. Out of 37 M1 mutant lines, morphologically diverse lines were observed with the highest plant height increase:
15.5 cm on 6-2-4-1 mutant line, the highest plant shoots increase: 5 shoots on 6-6-7-8 mutant line, the highest leaf number increase: 17 leaves on 6-6-7-8 mutant line, and the highest leaf area increase: 47.24 cm2 on 6-2-5-2 mutant line. In conclusion, gamma irradiation and somaclonal variation could increase genetic variation of mutant rodent tuber lines as shown by morphological data.

Keywords : Thyphonium flagelliforme , Gamma-Irradiation Somaclonal-Variation, Morphology-Variation
EFFECTS OF CHROMIUM ON PROTEIN AND CARBOHYDRATE LEVELS IN THE MANTLE OF FRESHWATER MUSSEL Anodonta woodiana (Lea, 1834)
Authors: Nugroho Andhika Puspito , Nugraha Raditia , Prasetyaningrum Nova
Published: September 2015

Chromium is one of the technical importance metals found in the aquatic environment at increasing concentrations, resulting from metallurgic, refractory, chemical, and tannery in­dustries (Satyaparameshwar et al., 2006). The metal is known to be essential for all animals such as maintenance of normal glucose tolerance (Chassard-Bouchaud et al., 1989). It also involves in metabolisms of lipids, proteins, nucleic acids, and mineral substances (Pechova & Pavlata 2007). At elevated concentrations, chromium is toxic to mussels, resulting in changes of mRNA expression, immunomodulation, DNA stability, and stress response path­ways (Franzellitti et al., 2012). Swan mussels (Anodonta woodiana) living at the interface of the free-flowing water and the sediment phase of many lotic freshwater ecosystems are known to accumulate metals in their body. Mussels require carbohydrates as main energy source for their metabolic processes (Honkoop et al., 1999). Proteins are also required by mussels for catalyzing biochemical reactions, transport and storage of molecules in and out, or within cells, and have structural and mechanical functions (Albert et al., 1994). Proteins and carbohydrates are also important components in the shell formation (Marie et al., 2007; Marin & Luquet 2004). Mantle secretes proteins and carbohydrates into extra pallial fluid, which is directly adjacent to the shell. The objective of this research was to study the effects of Cr on the protein and carbohydrate levels in the mantle of A. woodiana.
Introduction of Mycorrhizae Propagules and Rhizobium as Growth Promoter Legumes on Marginal Lands.
Authors: Nurhidayati Tutik , Ermavitalini Dini , Setyaningsih Endang Purwanti , Satriyono Agus
Published: September 2015

The objectives of this study is to evaluate the effect of mycorrhizae propagules and rhizobium on the growth on legume plants (Arachis hypogea) in marginal land. The experiment was conducted in Nguter village Lumajang, East Java. The results showed that mycorrhizae propagules stimulated rhizobium and plant growth by increasing plant height, dry weight and nodule weight. This results implied that mycorrhizae propagules stimulated and rhizobium were advantageous promoting growth at marginal lands.

Keywords: Mycorhiza propagul, Rhizobium, legume and Marginal land
Helicopter Load/Unload Operation Safety on Offshore Platform
Authors: Yonebayashi Hideharu , Collins Tim
Published: September 2015

On offshore oil/gas platforms that have no crane equipment, when a slick-line and/or an electrical wire-line job is required, helicopter load/unload operation is a common method for transporting materials such as winch units, power pack units, BOP units, lubricators, etc., from platform or offshore complex to the platform. A series of materials are separately transported by helicopter so that one lifted material can be within the helicopter maximum loading capacity. A package of transportation typically consists of 4-5 load/unload operations for a whole set of materials. Those frequent load/unload operations are done with a hovering action that has the highest risk among a series of helicopter actions (i.e. taking-off, cruising, and approach/landing). To achieve safety, all risk-mitigating factors are adequately incorporated into a plan that should be shared with all crews (pilot, company supervisor, slick-line/wire-line operators) in advance of the operation. In addition to summarizing general safety tips, this paper discusses mitigations from various point of views. As a result of considering ground crew's psychological response based on actual field experience, this paper recommends how to remove these mental factors that silently act on a helicopter marshaller's action. Moreover, fundamental measures are recommended to update marshalling methods and to use new generation helicopters that are designed for improved safety requirements.
Root Cause Analysis Solves Inoperability Problem with Downhole Flow Control Valves
Authors: Agarwal R. , Galiunas M. , Barrilleaux M. , Stewart C. , Burns M.
Published: September 2015

Eight downhole flow control (DHFC) valves were installed between 2007 and 2012, two in each of four deepwater wells in the Gulf of Mexico (GoM) by BP. Five of the eight valves failed to function correctly when the wells were subsequently commissioned within two to six month after installation. After the first three failures, down hole filters were implemented in the hydraulic control lines as a part of mitigations and remedial actions. The changes appeared to have solved the problem—until two further failures occurred in 2012. This paper presents the physics-of-failure (PoF) based root cause analysis (RCA) conducted to investigate the causes of the last two valve failures. Key elements of the investigation process are highlighted. These key elements can help to make any investigation efficient, effective, informed and objective. The investigation showed that even when a failed part is not available for failure analysis, symptoms of the failure can be used to identify the failed part(s).

The final two failed valves were in a single well that had been tested operable at the time of installation and shut in with completion brine in the tubing. Two months later, during commissioning of the wells, the valve sleeves failed to shift. Based on an examination of the few recoverable parts from the inoperable flow control systems and a careful review of the fluids to which they were exposed, the failure mechanism for the DHFC valves was identified as deposition of corrosion products on the sleeve that interfered with its sliding. The sleeves with surfaces hardened using quench-polish-quench (QPQ) nitriding process of 13% Chromium (13Cr) stainless steel corroded upon exposure to completion brine with trace oxygen and hydrocarbons with dissolved carbon dioxide from the pay zone.

The performance of DHFC valves with QPQ-nitrided 13Cr surfaces in deepwater wells can now be explained in light of the identified failure mechanism. Wells that were produced shortly after completion had operable DHFC valves since the produced hydrocarbon fluids were not sufficiently corrosive to attack the QPQ-nitrided 13Cr. However, wells which were not produced for at least two months after well completion had failed DHFC valves, since the completion brine along with hydrocarbons had sufficient time to corrode and impair the valves function.

Ten DHFC valves made from Inconel 718 have subsequently been installed, two each in five deepwater wells, and all ten have functioned satisfactorily. The recurrence of a similar incident has been systematically prevented. Further, use of QPQ-nitrided 13Cr equipment on other downhole applications has been reviewed for suitability.
Case History: First Lower Tertiary Multi-Zone Single-Trip Intelligent Completion in an Ultra-Deepwater Development
Authors: Joseph Kevin
Published: September 2015

Multi-zone single-trip (MST) technology is a completion method to perform sequential sand-control treatments to multiple zones in one trip down-hole. The primary advantage of the method is the operational efficiency and resultant cost-savings. The paper presents the challenges surrounding the latest one of five Gulf of Mexico wells installations in an Ultra-Deepwater project, describes the systems used and presents their key factors of success. For the first time, an intelligent well completion was successfully installed together with the MST system, further improving the producing capabilities to collect reservoir information and to manage fluid production.

The paper also discusses the technological advantages of the MST completion method, key lessons learned to date and the major success factors in the project specific to the completion operations. The paper is structured around well integrity, operational efficiency and completion excellence. Well integrity is accomplished by ensuring that completion components conform to the extreme downhole well conditions, maintain well control; and keep zone isolation during high-pressure frac-pack treatments. Operational efficiency was attained by clear guidelines, right personnel involvement, identifying and eliminating any possible operational risk. Completion excellence was achieved by system built-in redundancy features for flawless executions and software modeling to simulate downhole conditions from installation through production phases. The intelligent completions capability and the value added to the system are also presented.
Screen Erosion Guidelines for Sand Control Completion and Sand Production Management. Case Study West Delta Deep Marine (WDDM) Offshore Egypt
Authors: Mahmoud H. S. , Ali A. M. , Abdel Sayed A. A. , Zalam E.
Published: September 2015

The West Delta Deep Marine (WDDM) fields are a Pliocene gas fields located in offshore Nile Delta, approximately 120km North-East of Alexandria, Egypt. These fields are comprised of sandstone reservoirs which are dominated by unconsolidated sandstone.

Sand production has become one of the main issues in WDDM since the discovery of a hole in the body of a liquid outlet valve from the onshore slug catcher. On further inspection, it was discovered that the hole had developed due to the presence of sand/fines causing erosion at the interface in the liquid handling system. Scarab-Saffron field was the primary source of sand production in WDDM with screen failure as the cause of the problem.

This paper details a method for determining maximum safe production rates for sand control wells. This method was developed from a thorough compilation of data from around 51 sand control wells. As a result of this analysis, a simple function of screen erosion limit has proved to be very reliable at identifying wells operating safely from those resulting in damaged screens or unacceptable amounts of produced sand.
Minimum Facility Platform for Sub-Commercial Reservoirs in the Gulf of Thailand
Authors: Chanwith B. , Pheerasak P. , Thitinun S. , Natthawadi L. , Tanadcha T. , Taweepong M. , Yossaran P. , Wanvisa S. , Suchada P. , Pongpat H. , Ratchada L. , Supamittra D. , Vuthiphon T. , Warakorn K. , Wiwit S. , Penporn S. , Choosak K. , Saran U.
Published: September 2015

According to PTTEP reservoir data for the Gulf of Thailand, some of its prospects contain small amounts of reserves that cannot be developed commercially based on the current Conventional Wellhead Platform (CWP) design. In order to profit from these sub-commercial gas reservoirs, a Minimum Facility Platform (MFP) with lean facilities and optimum size must be selected to ensure worthwhile preliminary economic results in such marginal reservoir production. Compared to employing a conventional wellhead platform, in this case, a project team has to achieve a target cost saving of approximately 20% more than would be gained from use of a conventional design. Regarding projecting a production profile, the MFP should be installed in early 2017.

This MFP is to be designed for 5 years of production life. Maximum production capacities are 40 MMSCFD gas, 1,400 BOPD and 2,000 BWPD. The production is for sour service with a maximum export of 50% CO2 and 50 ppmv of H2S

The following are featured as new characteristics of the MFP design: Reduced number of wellhead slots from 16 to 9-15Commingled flow lines to reduce the number of actuated on-off valvesCombined and integrated functions of test separator to booster compressor packageUse of 100% solar power with battery backup and removal of Thermal Electric Generator (TEG)Reduced export pipeline size from 12”/16” to 10”/12”Reduction of overall deck area by 20%, resulting in wellhead platform structural weight reductionOptimized material selection and corrosion inhibitor systemOptimized equipment specification to align with manufacturer's standardRemoval of closed drain system, drainage to be handled by export gas pressurization

With the development governed by the MFP concept, 24% of the sub-commercial field volumes could be potentially recovered to support the added sustainability of the energy supply in Thailand. In other words, these previously sub-commercial prospects could be re-evaluated and re-integrated into new field development plans. Furthermore, the MFP could replace future Conventional Wellhead Platforms for the further improvement of the overall NPV project.
Human Factors Risk Programs Implementation at Drilling Material Dispatch Unit and Well Equipment Repair Workshop
Authors: Al-Dhamen Fahad , Gopaul Garry , Al-Shatti Ahmad , Al-Khaldy Ali
Published: September 2015

This paper looks at two operations vital to the Drilling Operations at Kuwait Oil Company (KOC) –the Drilling Material Dispatch Unit and Well Equipment Repair Workshop. Both support the entire Drilling and Work-over Program in Kuwait Oil Company (KOC), and significantly affect not only the daily oil production but also future projected growth objectives.

It examines in depth the various human factors categories -individual, job and organizational factors that adversely affect HSE performance in these operations, and looks at solutions to these unique problems. The paper is unique in its approach, in that it offers a practical insight into the many human factors challenges, some which require long term solutions, that have emerged in a highly growth oriented E&P environment.

Applications

The paper compares the human factors identified in these areas, to industry recognized “Performance Influencing Factors”. These are factors that adversely affect human performance and increase the likelihood of accidents, and illustrates that human factors is a common issue faced by others in the industry. Control Measures to reduce risks due to human factors are presented, which will be useful for implementation in many similar operations supporting the drilling function or maintenance workshop type environment.

Results & Conclusions

Mismatches between job requirements and people's capabilities provide potential for human error and accidents. This is particularly important when dealing with the issues of unskilled labor combined with workforce literacy challenges in an industrial setting.

Physical match includes the design of the workplace and the working environment, while mental match includes perception of tasks and risks. Both physical and mental matches must be considered in one's specific work environment, through risk assessments and subsequent implementation of control measures.

Significance of subject matter

Successful human factors integration can bring benefits not only to Health, Safety & Environment (HSE) performance, but also to productivity in companies, by proactively identifying and rectifying human performance issues related to the organization, job and the individual.
Proving the Concept of Unconventional Gas Reservoirs in Saudi Through Multistage Fractured Horizontal Wells
Authors: Al-Momin Ali , Kurdi Mohammed , Baki Sohrat , Mechkak Karim , Al-Saihati Ali
Published: September 2015

Saudi Arabia has embarked on an exploration journey for its unconventional gas resources by recently targeting three different areas across the Kingdom. The targeted formations include tight sandstone, shale and tight carbonate with a permeability range of 200 nano-darcy to 0.1 MD. Extensive exploratory work has been performed in each of the areas through drilling vertical wells to identify and characterize potential targets through coring and open-hole logging along with flow potential testing of those targets after placing vertical fractures, which is beyond the scope of this paper. This paper highlights the progress of the unconventional program through drilling horizontal mono-bore wells and stimulating them with multistage fracturing using Plug-N-Perf technique. Three case studies, one from each targeted formations, are presented in this paper. The subjects addressed are: Well completion including the selection of tubing and liner sizes, metallurgy and grades along with performing stress and thermal analysis simulating the expected loads during proppant fracturing to determine the maximum safe loads at each stage.Proppant fracturing design including the number of stages and clusters, the spacing of stages, proppant type, size and volume, and fracturing fluid systems. The design is based upon the geomechanical and petrophysical interpretations of the openhole logs together with onsite calibrations and measurements.Plug-N-Perf and fracture stimulation operations and executionFracture fluid clean up and flow testing

The paper summarizes the workflow adopted, the lessons learned and challenges overcome after drilling, completing, fracturing and flow testing of several unconventional gas wells in Saudi Arabia.
Drilling Through Layers of Unstable Shale Formations and Depleted Sand Sequences, the Managed Pressure Drilling / Wellbore Strengthening Approach to Successfully Drill Offshore Development Wells. A Case History
Authors: Henry I. , Hernandez J. , Ngan A. , Arnone M. , Boutalbi S. , Lagrandeur C.
Published: September 2015

Two hole sections (12-1/4″ × 14-3/4″ and 10-5/8″ × 12-1/4″) were planned to be drilled through sequences of unstable shale and depleted sand packages with no drilling windows, which are defined by the shale Wellbore Stability Gradient (WBSG) delimited by the “intact wellbore wall zero failure degree” and the depleted sand fracture gradient criteria. Historically, significant non-productive time (NPT) associated with wellbore instability and lost circulation had resulted in sidetracks and other costly remediation in both hole sections. The operator and the service provider have identified the Constant Bottomhole Pressure (CBHP) variant of Managed Pressure Drilling (MPD) and wellbore strengthening as the necessary technology approach to safely drill through both challenging hole sections. Dynamic and static wellbore strengthening were applied to increase the near wellbore stresses across the depleted sands to create a drilling window, whilst the MPD CBHP was used to mitigate bottom hole pressure fluctuations and cyclic stress across the shale packages.

The MPD well evaluated in this paper had just four hours of non-productive time related with downhole problems and wellbore stability, a minimal fraction when compared to the 980 hours lost in the previous conventional offset well. The MPD well did not require any back reaming operation, whereas the offset well in the area required 7 back-reaming events to get a good quality wellbore. A total of 533 hours were required to drill the 2 hole sections in MPD compared to the 2,410 hours required to drill the same sections conventionally in a previous offset well in the area.

This paper summarizes the key MPD planning, engineering, results obtained and lessons learned that delivered a successful campaign of producer wells.
Tractor-Conveyed Magnetic Fishing in an Extended-Reach Lateral Completion
Authors: McMullen Chris , Hathaway W. Ephraim
Published: September 2015

As operators in the Appalachia basin explore the Utica formation that underlies the previously-developed Marcellus shale, economic and environmental drivers have pushed drilling rigs to their limits in delivering wells that are both deeper and have longer lateral sections. These extended-reach lateral wells, with total measured depths (TMD) exceeding 18,000 ft, impose new completions challenges stemming from technical limits and the utilization of new technologies. This paper will demonstrate the need to adapt while dealing with new constraints. Specifically, this paper will report on the successful use of e-line, a tractor, and a magnet to retrieve a fish from plug-and-perf operations in an extended-reach lateral.

One major challenge in performing a plug-and-perf completion on the extended-reach lateral in this case study was that the toe of the well extended further than could be cost-effectively cleaned out with a service rig or coiled tubing. Therefore, large-bore cast iron permanent frac plugs, which are designed to be produced through, were used to isolate frac stages in the toe. Before pumping a subsequent stage, a dissolvable ball was seated on the plug to isolate the previously fractured stages.

While plugging and perforating, the wireline adapter kit of the plug setting tool backed off the toolstring, creating a fish above the plug. It was unclear if the adapter kit was still whole or had broken into multiple components. The challenge in recovering the fish was that if it had disassembled, smaller components of the assembly could potentially slip through the bore of the recently set plug. If this occurred, the plug would need to be milled before a fishing attempt could be made. Therefore, it was concluded that the fishing tools needed to be able to delicately engage the fish but still achieve a sufficient bite to hold the fish as it was dragged up the lateral. An overshot tool conveyed on coiled tubing was deemed too aggressive. Similarly, pumping down a wireline fishing tool was dismissed as the force from the pump down could potentially push the fish through the bore of the frac plug. Therefore, the decision was made to tractor-convey a rare earth magnet on e-line. This method successfully retrieved the fish on its first run, saving at least 3 days compared to the next-best recovery method.

This paper will detail the planning and execution of this fishing operation in order to provide insights for planning other extended-reach lateral completions. Specifically, this paper will show that existing technologies can be employed to overcome the challenges associated with fishing in extended-reach laterals.
Implementation of Drilling Systems Automation - Halifax Workshop Summary: Industry Standards, Business Models and Next Steps
Authors: Florence Fred , Chapman Clinton , Macpherson John , Cavanaugh Martin
Published: September 2015

The SPE Drilling Systems Automation Technical Section (DSATS) is a committee tasked with supporting the growth and implementation of drilling automation. In September 2014, DSATS held a dual-stream workshop in Halifax, NS, Canada with focus on both the technical and business issues relating to implementation of this new technology. The workshop identified key business issues, both blockers and enablers and, for the first time, proposed a step towards a potential industry technical guideline that allows the machines and models used in drilling to communicate in real time. Workshop participants identified future actions that will continue to advance the development of drilling automation. This paper summarizes both the topics presented and the actions identified as necessary to advance the implementation of drilling systems automation.

The workshop used two parallel tracks: a technical track dealing with the communications technology needed for drilling systems automation, and a business track focused on technology implementation issues. This novel format spurred a crosspollination of ideas since attendees were free to attend either track and switch between tracks during the conference, thereby contributing to topics of interest.

The technical track included work to define a common interface for equipment control based on the OPC-UA communications protocol and a rig information model, or data dictionary, which is necessary for modeling the process of drilling a stand using normal drilling machinery. The business track examined issues surrounding the use of large data sets, sensors and problems encountered when using them, reliably, in real time. Participants discussed their concerns with existing drilling contracts which do not always cover the legal responsibilities of all parties involved in the construction of a well using an automatic drilling system.

The workshop developed a rig information model as a guideline for data communications in the automation of drilling a stand. This model will be the basis for developing an open standard that all interested parties can use in creating drilling automation products. Additionally, the workshop initiated the work on transferring drilling automation technology into the open business arena. DSATS working groups and future planned workshops will further explore critical topics, such as data quality, modeling, and simulation.
Using Swelling Materials to Control Fracture Complexity: Experimental Study
Authors: Gomaa Ahmed M. , Sun Hong , Nelson Scott , Qu Qi , Boncan Go Virgilio
Published: September 2015

Enhancing complexity of the created fracture geometry is the primary challenge for hydraulic fracturing treatment design in shale formations because of their stress anisotropy. Near-wellbore diversion may be required to evenly stimulate all perforated clusters; far-field diversion inside the created fracture may induce additional branch fracturing by overcoming the stresses holding the natural fractures closed. Increasing the pressure within the fracture enables further fracture extension.

The objective of this study is to experimentally confirm the bridging ability of a swelling diverter particle and to establish a correlation between increase in pressure and its location (far-field or near-wellbore) with time, pressure, proppant and diverter loading, fluid viscosity, and fluid types.

The study confirmed that increasing fluid viscosity and/or reducing flow permeability will increase the flow resistance (and therefore pressure) in any path. For fracturing application, an HEC fluid with extremely high viscosity (millions of centipoise) developed maximum increase in pressure of 3 psi/in. of fracture length. Swelling particles of the type described in the study can increase their diameter in water by up to 500% at 75°F and 800% at 175°F in water. If this growth occurs during flow in a fracture, it can preclude further movement and create a “bridge” that increases the fluid pressure inside the fracture. Injecting 100-mesh sand with the particles increased the bridging pressure from 12.5 psi/in. of fracture length for the particles alone to 125 psi/in of fracture length. The authors believe that this occurs because the sand particles create friction with the fracture face. Particles swell more rapidly in water than in 30 pptg linear guar gel, and more rapidly in linear gel than in crosslinked 30 pptg guar gel. Therefore, variations in the fracturing fluid can control the swelling of particles, a factor that can be used to “place” the diverter material deep in the fracture for far-field diversion, or closer to the perforations for near-wellbore diversion. An oxidizer breaker can be used to break the swollen particles, leaving no visible precipitation as indication of damage. The results from this paper can help in understanding the diversion parameters required to effectively enhance the complexity of the fracturing geometry.
Machine Learning as a Reliable Technology for Evaluating Time-Rate Performance of Unconventional Wells
Authors: Fulford David S. , Bowie Braden , Berry Michael E. , Bowen Bo , Turk Derrick W.
Published: September 2015

Production Data Analysis is a practice wrought with inconsistencies. In the application of any single model, the quantity of answers arrived at by experienced evaluators is often equal to the number of evaluators analyzing the data. The cause of such inconsistency is bias on the part of evaluators. While the colloquial use of bias typically implies systematic error, in this paper we define bias as an expression of belief by the evaluator. With the lack of recognition of bias, no manner exists in which to gauge its accuracy. A method that requires explicit expression of one's bias in rate-time decline behavior can provide an objective manner in which to evaluate it.

In this work, we present a machine learning method to forecast production in unconventional, liquids-rich shale and gas shale wells. Gong et al [2011] developed a method for probabilistic decline curve analysis using Markov-chain Monte Carlo simulation (MCMC) as a means to quantify reserves uncertainty, incorporate prior information (i.e. bias), and to do so quickly. However, their approach resulted in limited use of discrete P10, P50, & P90 production forecasts, as these often did not align with production data. We extend their approach by a) utilizing the Transient Hyperbolic Model (THM) to represent the various flow regimes present in unconventional wells, b) a methods for construction of representative "percentile neighborhood" forecasts, c) construction of Type Curves from an analyzed well set, and d) a modified likelihood algorithm to improve the accuracy of discrete forecasts. The accuracy and calibration of the method is demonstrated by an analysis of 136 wells in the Elm Coulee Field of the Bakken. Quantification of change in rate-time behavior due to completion design, and the inference physical behavior and properties, is demonstrated using a tight oil play in the Cleveland sand formation of the Anadarko Basin, and a shale play in the Wolfcamp formation of the Permian Basin.

We show that this implementation of supervised machine learning, in combination with well-calibrated bias, improves the estimation of uncertainty of the distribution of forecasts. Additionally, hindcasts performed at various time intervals results in accurate Mean 5 year cumulative production. We observe that the "percentile neighborhood" forecasts are reasonable fits of production data comparable to those that may be created by a human evaluator, and that the type curve computed is representative of the decline behavior of the wells upon which it is based. We conclude that, given the speed and accuracy of the process, machine learning is a reliable technology as defined by the SEC, and can replace the process of manual production forecasting by human evaluators for most unconventional wells with consistent trends of production history.
Secret Weapon Against the Red Queen: Using Chemical Packers and Degradable Mechanical Diverters in Refracturing Operations
Authors: Fragachan Franisco E. , Babey Andrew G. , Arnold David M. , Heminway Evan M. , Yuan Feng
Published: September 2015

Over the last five years, horizontal drilling, fracturing and multi-stage completion technology advances in unconventional shale resources has helped US oil production grow by 65 percent.1 Even though, production rates in unconventional plays can decline dramatically, up to 70% in the first year. To replace the loss in production, oil companies have traditionally drilled more wells. This decline phenomenon is called the Red Queen, named after the character in Lewis Carroll's “Through the Looking-Glass” who tells Alice “(Run) Faster! Faster! It takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!”2 Refracturing may become the secret weapon against the Red Queen that allows existing shale wells to sustain hydrocarbon production without new wells being drilling.

In this paper, several case studies will highlight how temporary and degradable chemistry in both liquid and solid materials can be introduced as a means to provide temporary isolation between zones in shale refracturing operations. These chemical diverting agents forms a solid impermeable barrier or seal that in time will break or degrade to liquid form, leaving the existing zone that was diverted open to permit flow.

First scenario will focus on an open-hole sidetrack well drilled in an existing vertical well. Through the use of a chemical packer for support and isolation, a retrievable six zone sliding sleeve system was deployed. The second case and third case histories will focus on the impact degradable mechanical diverters are having not only on the refracturing market, but how they could potentially be used on new wells to increase zonal coverage and help mitigate the need for refracturing by increasing zonal coverage during the initial stimulation treatment.

This paper will present and discuss this unique application and performance of the fracturing completion design, and provide another approach of re-fracturing operation for unconventional plays.
Forecasting Production Performance in Reservoir-Network Coupled Systems with Asphaltene Modeling
Authors: Valbuena Ernesto , Barrufet Maria , Killough John
Published: September 2015

This manuscript presents the development and implementation of a new integrated reservoir-network compositional simulator for analysis of asphaltene precipitation within tubing and production pipelines. The need for integrated models for flow assurance analysis in assets with high potential of asphaltene precipitation is demonstrated for the following scenarios: i) natural depletion, ii) downhole asphaltene inhibitor injection, and iii) artificial gas-lift system.

Fully-implicit compositional formulation forms the basis for reservoir and network simulators. Implementation of a tightly-coupled solution allows assessing mutual interaction between subsurface and surface components. Compositional delumping from reservoir to network fluid characterizations enables accurate modeling of complex thermodynamic phase behavior for asphaltene precipitation. The Peng-Robinson equation of state with volume translation models phase equilibria in coupled solution and asphaltene precipitation in network pipelines. Asphaltene accretion to internal pipe walls is estimated with a mechanistic transport model to forecast reduction of flow area and its impact on production performance.

Solid precipitation and deposition in the production system have a negative impact on production rates, pressure management, and field operations. Results show increased thickness of asphaltene deposits in time, reaching up to 50% diameter reduction after a few months of production for the cases evaluated. Pipeline diameter increase at wellhead promoted asphaltene formation, caused by fluid velocity reduction. Bottomhole injection of asphaltene inhibitor reduced formation of solid deposits by 90%. Artificial gas-lift systems influence deposition profiles due to fluid compositional changes and velocity in the wellbore column.
Environmentally Preferred Process for Efficient Boron and Hardness Removal for Produced Water Reuse
Authors: Cao Jiasheng , Monroe Stephen , Hendry Dolly
Published: September 2015

Treatment and reuse of produced water has become increasingly attractive. The complicated nature of produced water, however, and its variability make it challenging to reuse. Boron (B), a common component in produced water, is a concern when reusing produced water for hydraulic fracturing fluids. Excess boron in water can interfere with the timing of crosslinking reactions in hydraulic fracturing fluids, and premature crosslinking can increase friction pressure (horse power) when the fluid is being pumped. Lowering the boron concentration in produced water, therefore, will help to prevent or reduce formation damage and increase the stability of the hydraulic fracturing fluid. This paper presents a patent-pending and environmentally preferred process for boron and hardness removal from produced water.

The traditional approach to boron removal has been to add chemicals (like activated alumina (Al2O3) or cerium oxide (CeO2)) or a chemically impregnated material (activated carbon) and clay as sorbents for boron removal from produced water, but these techniques have seen limited success. In these conventional approaches, sorption efficiency was affected by solution pH, initial boron concentration and other contaminants in the water. The method presented in this paper, however, is an environmentally preferred and simple process of adding liquid sodium silicate (Na2SiO3) to produced water for boron and hardness reduction. Efficient boron removal from more than 150 mg/L to less than 30 mg/L was achieved using this process, while at the same time, total hardness (as CaCO3) was reduced by more than 80%. While the waste solids that were created do contain high levels of calcium and magnesium silicate, it is proposed that they could be used for cementing material for oil industry applications thereby reducing the environmental impact of the process. Compared with other methods such as boron-selective resin, reverse osmosis (RO) or chemical sorption, this process exhibited better performance in the efficient removal of boron and hardness from produced water.
Geology Driven EUR Prediction Using Deep Learning
Authors: Crnkovic-Friis L. , Erlandson M.
Published: September 2015

We present a geology driven deep learning Estimated Ultimate Recovery (EUR) prediction model for multi-stage hydraulically fractured horizontal wells in tight gas and oil reservoirs. The novel approach was made possible by recent development in the field of deep learning and the use of big data (200,000+ geological data points and 800+ wells). A Deep Neural Network (DNN) was trained to learn the relationship between geology and the average EUR (estimated by decline analysis). The model was validated on wells from other geological regions to show its generalization capabilities.

The DNN model we present significantly outperforms both volumetric estimates and type curve region averages (even on highly developed acreage). It generalizes well across geological areas with limited loss in accuracy. On a test region not used during model creation it produces a mean absolute percentage error of 33.1% compared to 69.7% for type curve averages. Oil and gas recovery are treated separately and the model outputs the oil to gas ratio. The model was trained and tested on data from the Eagle Ford Shale but the general methodology should be applicable to other resource plays.

The model is applicable in the exploration stage, as it only requires geological data. This is important as type curve regions require production data to be constructed, and are thus not available until the area has been in production for some time.
Evaluation of the EIF Onshore Discharges Tool for Assessing Environmental Risk from Accidental Spills and Leaks Associated with Hydraulic Fracturing Operations
Authors: Firth S. K. , Musdalslien U. I. , Hagemann R. E.
Published: September 2015

Prompted by regulatory requirements to work towards “Zero harmful discharges” to the Norwegian Sector of the North Sea, the oil industry developed the “Environmental Impact Factor (EIF) Produced Water” risk management tool. This helps to identify best measures for reducing risk from the offshore discharge of produced water and is used by all operators in the Norwegian Continental Shelf for reporting continuous improvement. Its success has led to the application of the EIF concept as part of the risk evaluation for other types of discharge, both onshore and offshore. This paper presents the EIF Onshore Discharges tool and evaluates its use for application to hydraulic fracturing (HF) operations.

The EIF Onshore Discharges tool uses quantitative modelling techniques in combination with generic principles for environmental risk assessment to predict the volume of three receptor compartments (soil, groundwater and surface water) potentially impacted as a result of intentional or unintentional liquid discharges or releases. In this instance the tool has been used to predict potential impacts from a range of accidental release scenarios associated with hydraulic fracturing (HF) operations. These included surface and subsurface spills/leaks of HF fluids and flowback water. Various HF fluid blends were assessed using a variety of release locations to represent the range of key factors affecting risk. The purpose has been to raise awareness and identify proper risk mitigation measures.

The results indicated a large range in potential impacts arising from unmitigated accidental releases. This variation could be explained by differences in the release scenarios, HF fluid composition and variability in receiving environment conditions. The results also appear to be in line with impacts experienced from known spills, adding confidence to the tool's predictive ability.

Whilst the probability of such releases occurring is very low, the fact that some scenario/chemical combinations have the potential to cause significantly higher impacts than others helps identify key considerations for risk management decisions. In particular, the modelling demonstrated that some HF fluid blends posed significantly higher environmental risk than others, prompting consideration of chemical substitution as part of the overall risk management strategy for the HF operations. Other ways in which the tool aids risk management decisions include identifying higher risk locations where additional risk prevention and/or mitigation measures would be warranted and helping to define spill response measures.
End-to-End Data Provenance
Authors: Rundle R. T. , Vuurboom R. , Duroy Y.
Published: September 2015

Data provenance is the chronology of an object, i.e., all the transformations and actions that modified the state of the object from the time of creation to the present. End-to-end data provenance is the ability to account not only for the data provenance of a single object, but also to account recursively for the data provenance of all other objects that affected the state of the object. The purpose of data provenance is to help ensure data integrity.

Modeling has become an important aspect of shared earth problems. As the role and extent of modeling of the subsurface expands and its use is taken up by larger teams, determining the provenance of data becomes ever more important. The explosion of data and the appearance of increasingly diverse teams require the establishment of better data provenance to guard the integrity of the modeling results. Such a data provenance model is presented in this paper.

The economic consequences of such an approach are significant: better integrity of modeling results leads to more confidence in those results, which reduces perceived risk and, in turn, can improve the economic performance of field development.

The solution to the problem of end-to-end data provenance has six elements: The ability to uniquely identify objects of the shared earth problemAn object repository that supports federation and extensibilityThe ability to associate an immutable change history with each objectThe loose coupling of metadata and actual data of an objectClient-side caching of actual dataA comprehensive security model for the object.

Each of these elements solves an important aspect of ensuring data integrity. Such an approach is increasingly important as model-based approaches become ubiquitous, and the available data become more voluminous, and the teams that handle the data and modeling results become larger and more diverse.