bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Pharmaceutical Care Interventions on the Quality of Life of Group of Hypertensive Patients
Authors: Akonoghrere Rita O  , Arute John E  , Akparobore Akpevwe
Published: August 2016

Studies have shown that pharmaceutical care interventions have the potential of reducing hospital stay and drug therapy problems; it can also improve patients' quality of life. The primary objectives of this study was to show how pharmaceutical care interventions could resolve actual drug therapy problems and prevent potential drug therapy problems; also, to assess the change in the quality of life of hypertensive patients after such interventions. An uncontrolled prospective study was done. Hypertensive patients were recruited at the Medical Out-patients department (MOD) of Central Hospital Warri. Initially 104 patients were recruited, however, a total of 65 eligible patients were eventually used to asses for quality of life. Data were obtained using data collection forms; blood pressure was monitored using a sphygmomanometer, and patients were scheduled for follow up periodically for 6 months. Clinical outcomes and humanistic outcomes were assessed using the SF12 health survey form, and subsequently scored. DTPs were identified, case by case. All identified DTPs were reported in the patients’ pharmaceutical care data collection forms. Relevant descriptive and inferential statistics on data collected were performed. 65 patients were eventually followed up, 21.5% of them were males while 78.5% were females, with 72.3% of them aged 51years and above. Most of them (61.5%) had a family history of high blood pressure; 40% of them were diagnosed to have hypertension and diabetes; only 18.5% of them obtained their prescription re-fill from the hospital pharmacy. At the end of the study, a significant difference in the systolic blood pressure of the patients was discovered and there was a statistically significant association between DTP resolved/prevented and the pharmaceutical care intervention (p<0.001). The correlation between DTPs resolved/ prevented was significant in two domains of quality of life measure – the mental component summary (MCS), and the bodily pain domain. Pharmaceutical care provided to hypertensive patients in a secondary health facility in Warri, Nigeria, resolved some of the drug therapy problems identified and improved patients’ quality of life.
Study on Seasonal incidence of Leaf webber Diaphania pulverulentalis on mulberry
Authors: Bhagyamma C. T. , Kumari N. Vijaya
Published: August 2016

Mulberry, the sole food plant of silkworm Bombyx mori L is prone to various pests and diseases which reduce the quality and quantity of leaf there by silk production. Among various defoliators Leaf webber (Leaf roller) Diaphania pulverulentalis is one of the major pest which causes extensive damage to the mulberry gardens. The incidence of this pest is mainly seen in the major sericulture districts of Andhra Pradesh especially in Ananatapuramu. Hence, the present study is carried out to know the seasonal incidence of the leaf webber on mulberry and its intensity level.
Fracture Diagnosis in Multiple-Stage-Stimulated Horizontal Well by Temperature Measurements With Fast Marching Method
Authors: Cui Jingyuan , Yang Changdong , Zhu Ding , Datta-Gupta Akhil
Published: August 2016

Downhole-temperature measurement is one of the solutions to understanding downhole-flow conditions, especially in complex well/reservoir domains such as multistage-fractured horizontal wells. In the past, models and methodologies have been developed for fracture diagnosis for multiple-stage-fractured horizontal wells. They are based either on a semianalytical approach for simplicity or on reservoir simulation for generality. The challenges are that semianalytical models are not robust enough to describe complex fracture systems, whereas numerical simulation is computationally expensive and impractical for inversion. To develop a comprehensive approach to translate temperature to flow profile, we adopted the fast marching method (FMM) in simulating both heat transfer and the velocity/pressure field in the interested domain (heterogeneous reservoir with multiple-fractured horizontal wells). FMM is a new approach that is efficient in front tracking. Previous studies show a significant success in the investigation of pressure-depletion behavior and shale-gas production-history match. By the nature of heat transfer in porous media, the thermal-front propagation would lag behind pressure, and the noticeable temperature change in the reservoir only happens near hydraulic/natural fractures. FMM can be used to efficiently track the heat front that is associated with the flow field.

In this study, we solve the thermal model in porous media by transforming the general energy-balance equation into a 1D equation, with the diffusive time of flight (DTOF) as the spatial coordinate system. Besides the diffusive heat conduction, the convection, Joule-Thomson effect, and viscous dissipation are considered in the model. The inner boundary of the model is carefully handled, and the drainage volume of each fracture is calculated to identify different inflow temperature related to flow rate at perforation locations. The model was validated by the finite-difference approach. Examples are presented in the paper to illustrate the application of the new method. The approach can be used to quantitatively interpret temperature measurements to fracture profiles in horizontal wells.
Application of Under-Balanced MPD in Fractured Granite Formation of Indonesia
Authors: Chen Peng , Wang Xi , Chen Lei , Wu Meng , Xin Junhe , Cheng Cunzhi , Chen Zhaofa
Published: August 2016

A lot of wells were drilled in the fractured granite formation of Indonesian Jabung Block without any oil and gas show. However, a discovery was made by the utilization of under-balanced MPD technology. This paper gives a description of the technological process of the MPD technology and equipment used in the exploratory well Basement-1#.

The 8-1/2in. hole section was drilled by application of MPD technology. The actual well depth is 8,269 ft, and the MPD hole section is between 4,993ft-8,269ft with footage of 3,276ft. The under-balanced drilling operation with managed pressure, tripping under managed pressure, displacement of weighted drilling fluid and overflow monitoring etc. had been successfully carried out during the MPD operation. Backpressure at wellhead was maintained in between 50-135psi. The abnormal downhole condition was monitored by little change of flow rate in and out of the well. Overflow was controlled in time and fluctuation of bottomhole pressure was decreased by use of accurate operation of the MPD equipment. A system of a synthetic based Gas-To-Liquid (GTL) drilling fluid was used to keep a low density as 7.4ppg since the formation pressure coefficient is around 1.04. The system kept good and stable performance with suspension and carrying capacity.

The overall MPD process was effective without any problems. No losses occur, and non-production time was reduced. Success ignition was not sooner than drilling 30ft into the basement. 57 times of successful ignition were done in 300hrs of MPD operation. The longest continuous ignition reached 75hrs out of total 240hrs of ignition. The maximum total hydrocarbon reached 36.3% and revealed good hydrocarbon shows.

Under-balanced managed pressure drilling could contribute to discovery of oil and gas reservoirs, make benefit to assessment of productivity of oil and gas wells. In addition, it increases rate of penetration, save overflow treatment time, and improve well control process.
Risk Reduction in the Acquisition of Formation Evaluation Data With the Development of Small-Diameter Open-Hole Logging Tools
Authors: Williams P. J. , Mayor T. , Pereira A. , Lawrance S. , Samworth J. R. , James T. , Patel H.
Published: August 2016

Post-drilling open-hole log measurements made by wireline tools are most commonly transmitted to surface via wireline, but the trend is towards increased use of memory-capable tools with greater operational flexibility. The primary purpose of the original memory tools was to operate on wireline in intermediate and TD sections while offering a low-risk alternative to conventional tools in horizontal wells, bad hole conditions and other challenging well scenarios.

This wide operational envelope required the tools to be small-diameter to allow protected conveyance inside drill pipe, but it also required that measurement performance and associated environmental characterization be on a par with conventionally sized tools that generated the majority of the historical record.

The extent to which these goals have been achieved, using evidence from the over 150,000 wells logged with the most highly developed of the small-diameter tool types, is reviewed.

Standard response modelling is essential but insufficient to ensure optimum measurement performance. Findings from the performance in thousands of wells have been used to refine models, hardware designs and processing algorithms, including more precise control on the position of tools in the wellbore.

Log data from test wells and commercial wells are provided showing the measurement quality from small-diameter tools matches that from conventionally sized tools for the large majority of operations.

Log data is also provided from wells that had presented insurmountable challenges for traditional logging tools which demonstrate the conveyance flexibility and the reduced acquisition risk in using the small-diameter tools.

The significance of the findings is that the performance of the most highly developed small-diameter tools has evolved to the point where measurement quality is not a differentiating factor for the large majority of operations, allowing job planning to be driven by the other considerations, in particular the minimization of acquisition risk.
Enhancing Zonal Isolation With Expandable Cement System for Gas Field
Authors: Tanoto E. , Kusumawatie R. , Inayah F. , Widyarsa I. , Jaffery M. F.
Published: August 2016

HPHT well subjects zonal isolation and long term cement integrity into critical factor to achieve long term production life. Repeated cycles of high differential pressure and temperature tend to break bonding between cement, casing and formation. Microannulus as consequence of debonding will provide space. At gas wells, it will provide space for gas migration which may lead to sustained casing pressure. Providing zonal isolation is also important to ensure there will be no communication between two different formations or reservoirs

This paper discusses the design, execution and evaluation of cement technology implemented at 9 5/8-in HPHT intermediate liner. Special softwares were used to simulate gas migration risk and stress analysis to cement sheath. High risk gas migration and microannulus were expected based on sofware results. An expandable cement system was identified as a solution and deployed successfully. In order to achieve better understanding of behaviour of cement slurry at field application, laboratory experiments were performed. To achieve long term cement integrity, it is not only about design of cement slurry, mud removal is one of the key factor need to be considered. Best practices were perfomed to achieve the highest mud removal efficiency.

Expansion test was perfomed by using pressure curing chamber at 247°F. Expansion was detected for six days simulation which was considered as enough based on stress analysis simulation of compression, traction and microannulus cement sheath performed. It was indicated that expandable cement managed to eliminate microannulus which was created by pressure and temperature changes. Evaluation was performed by locating pressure sensor at the A annulus of 9 5/8-in liner and 13 3/8-in casing. The sensor indicated zero pressure at the annulus while drilling next two more section and during the production life of the well
Evaluation of Miscible CO2-Flooding to Improve Oil Recovery in a Clastic Heterogeneous Reservoir
Authors: Al-Khazraji Ahmed Khalil , Awang Mariyamni B.
Published: August 2016

Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to improve oil recovery and its applicability has grown significantly due to its availability, greenhouse effect and easy achievement of miscibility relative to other gasses. Therefore, miscible CO2-injection is considered one of the most feasible methods worldwide. For long term strategies in Iraq and the Middle East, most oil fields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various miscible CO2-injection scenarios on the performance of the highly heterogeneous clastic reservoir in Iraq. An integrated field-scale reservoir simulation model of miscible CO2-flooding is accomplished. The compositional simulator, Eclipse-300 has been used to investigate the feasibility of miscible CO2-injection process. The process of the continuous CO2-injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and water flooding processes have been performed, and it will continue until January 2063. The minimum miscibility pressure (MMP) for CO2 was determined using empirical correlation as a function of crude oil composition and its properties. Ten miscible CO2-injection options were undertaken to investigate the reservoir performance. These options included applying a wide range of the CO2-injection rates ranged between 1.25 to 50 MMScf/day. All development options were analyzed with respect to net present value (NPV) calculations to confirm the more feasible CO2development strategy. The results showed that the application of CO2-injection option of a 20 MScf/day attained the highest recovery of 28% by January 2063 among the others. The recovery growth was so minor by the increasing the CO2-injection rate above this level. Based on economic findings the option of 20 MScf/day also attained the highest net present value (NPV). The results showed that after January 2063, the oil recovery attained by the different CO2-injection options are less than the one attained by the waterflooding process. Therefore, the miscible CO2-injection became unviable economically after January 2063.
Reducing Risk: Questions Oil and Gas Leaders Need to Ask and Answer
Authors: Matthews Teg
Published: August 2016

This presentation discusses the framework for understanding and responding to risk in the oil and gas industry, and identifies best practices for gathering the right information and improving safety performance. Specifically, risk identification systems should be designed to identify and remediate precursors to injury. Successful systems gain employee commitment across all levels, understanding the causes of precursors through data analysis, and identifying and addressing precursors with sustainable mechanisms. They leave no stone unturned, leveraging data from all departments of the organization, including process safety information (e.g., operational upsets, design flaws, catastrophic fires, and other related variables).
The Principle and Application of a Novel Rotary Percussion Drilling Tool Drived by Positive Displacement Motor
Authors: Xuan Lingchao , Guan Zhichuan , Hu Huaigang , Li Jingjiao , Zhang Bo
Published: August 2016

Experience over the past decades has proved that rotary percussion drilling technology is one of the most effective ways in improving the rate of penetration in deep wells. In the rock breaking process, the drill bit's teeth are forced into the rock powered by the bit weight and impact load, then the contact surfaces of rock and PDC teeth are destructed gradually. The finite element software was used to simulate the process of one PDC tooth breaking up the sandstone with the rotary percussion technology. The force on one PDC tooth in rotary percussion drilling was constantly fluctuating, and the impact load added the instability of load curve. The maximum mechanical strain appeared at the fracture surface, but not the contact surface of the rock with the PDC tooth. When the rock broken reached a steady state, the ratio of eroding energy to total energy consumption stabilized at around 52%.

The research showed that rotary percussion drilling technology is still not mature in the aspects of high-efficiency, long-life, and low-cost. The improvement of the comprehensive performance of the percussion tools needs more intensive study. This paper's objective is to design a novel rotary percussion tool to generate impact load. This new tool uses a positive displacement motor that drives the hammer piston to rotate, meanwhile the piston hits the anvil to generate impulse pulse. Also this tool's impact properties were tested and analyzed through field experiments. The impact frequency of this novel tool is 25.7~37.2Hz, which is adjusted by the flow rate of drilling fluid. The peak value of impact load is 20~42kN, adjusted by spring's compression.

Drilling tests in laboratory experiments showed that the rotary percussion drilling can significantly increase the rate of rock broken, and the highest rate of speed-up compared with the common drilling is 64.2%. Increasing spring compression can improve the rate of penetration in these percussion drilling experiments. A good performance in drilling sandstone experiments in lab experiments proves that this novel tool is helpful in improving the ROP in drilling deep wells onshore and offshore.
Physical Concept Validation Testing Performed for a Pore and Fracture Pressure Margin Prediction System during Offshore MPD Operations
Authors: Johnson A. , Piccolo B. , Leuchtenberg C.
Published: August 2016

A pressure determination system (PDS) was field tested to progress Managed Pressure Drilling (MPD) from a reactive system to one that prevents well control events from initiating. Physical testing performed on an offshore drilling operation successfully demonstrated the capability of the PDS to detect a simulated, unsafe change in fracture margin without incurring significant losses in August 2014. A summarized overview of the test method, conclusions, and results will be discussed as well.

The PDS Pressure Control Valve (PCV) is designed to oscillate its position size in a repeatable and gradual fashion and analyze the behavior of Applied Surface Back Pressure (ASBP), Bottom Hole Pressure (BHP), and Flow Out indicators over time. In the event that average BHP begins to near a drilling margin, the behavior of the above indicators at the crest or trough of a wave cycle will momentarily deform indicating an unsafe change in a drilling margin trend that will eventually lead to a recordable well control event if wellbore pressure is not proactively adjusted. Since, average BHP has continuously remained within drilling margins during this process, any resultant gain or loss is negligible. Once the threat of a well control event is detected, the MPD PCV will adjust wellbore pressure to a safer value to prevent the occurrence of a well control event.

During field testing, the PDS concept was verified with two assessments, signal transmission reliability and simulated fracture detection. Both tests were performed in open hole of a medium depth well with a rotating and reciprocating drill string and the mud pumps running. The signal transmission reliability test validated that the PDS can oscillate PCV position in a controlled and consistent fashion as well as create highly repeatable behaviors in ASBP, BHP, and flow rate waves over time. The simulated fracture margin test demonstrated that the PDS has the sensitivity to detect a fracture margin at 20 psi above the driller's intended wellbore pressure with a negligible volume of losses while the PDS PCV oscillated wellbore pressure as described above.

Prior to field testing, a SIT (System Integrity Test) was performed on the PDS equipment installed on MPO's MPD Pressure Control Manifold (PCM) to ensure the system was prepared for concept testing. The SIT was performed with the MPD PCM isolated from well bore riser returns in August 2014. The field tests performed offshore, were previously performed as an initial test, at the MPO Dubai Training Center Flow Loop where the PDS concept was also successfully validated in a laboratory environment. During those tests, the sensitivity of the PDS system was also demonstrated by validating that a 4 inch Coriolis meter in a small, closed loop system was able to detect less than a 1 gallon difference in flow.
Study on Structure Parameters of Reverse Circulation Drill Bit Secondary Injector Device Based on Injector Coefficient
Authors: Yong Huang , Lihong Zhu , Deyong Zou , Hualin Liao , Jinying Wang , Jinshen Yan , Yugang Zhou , Zhibin Wang
Published: August 2016

The hollow-through DTH hammer reverse circulation continuous coring drilling technology has been successfully applied to well drilling. During its application, reverse circulation drilling sometimes does not work in broken formation or under leakage formation condition. Difficulty in sampling is another problem. These problems are primarily caused by the injected gas. It comes into the fissures and not drives the reverse circulation, thereby failing to generate an adequate pressure at the hole bottom to deliver the cuttings into the central channel.

The reverse circulation bit is the pivotal factor in the formation of reverse circulation. To improve the reverse circulation effect, this paper proposes that a secondary injector device be set at the central hole of the original reverse circulation bit. The injector device used for the hollow-through DTH reverse circulation bit is a gas injector designed with the gas injecting principle. Based on the structure principle of the injector and the actual structure of the DTH reverse circulation bit, it is used the bottom nozzle of the bit as injector nozzle and add a pressure diffusion slot, so a multi-nozzle injector structure at the bottom of the bit is formed.

The secondary injector device can effectively improve the reverse circulation effect of the hollow-through down the hole (DTH) hammer drilling technology. The influence of the four structural parameters, namely, secondary injector hole diameter d, center hole diameter D, injector hole angle θ, and distance h from the injector hole to the reverse circulation drill bit bottom, on the injector coefficient n was studied by computational fluid dynamics (CFD) simulation to determine the structure size. The CFD results were verified by experimental method. The results showed that the reverse circulation effect changed with the changes in the secondary injector device structure parameters d, D, θ, and h. A combination of structure parameters allowed the drill bit to achieve the best reverse circulation effect. Considering the effects of the four parameters, d=11 mm, D=44 mm, θ=30°, and h=180 mm were the more rational parameters. Moreover, laboratory experiments were conducted to verify the CFD simulation results. The simulation results that showed the variation of n with different structure parameters were compared with the experimental test results. The comparison showed an error of less than 15% between both results, further verifying the rationality of the structure parameters.

The hollow-through DTH hammer-based reverse circulation continuous coring drilling technology is featured by reverse circulation of fluid medium through the entire hole and continuous upward conveyance of the cores during drilling. This paper studies the structural parameters of the secondary injector device of the reverse circulation drilling bit in order to improve the rate of core recovery.
A Brief Introduction to High Temperature and Foam Free Water Based Drilling Fluids
Authors: Mojammadi Mojtaba Kalhor , Taraghikhah Shervin , Nowtaraki Koroush Tahmasbi
Published: August 2016

Water-based drilling fluids are the most commonly used of the mud systems. High Temperature and Foam Free Water Based Drilling Fluids has been designed for controlling the rheological and filtration and foam properties of water based drilling mud under down-hole conditions.

This unique drilling fluids system has been developed to improve water based drilling operation's speed and save the drilling cost while reducing their environmental impact for rheology and filtration control at high temperatures. Specially-formulated fluid has good lubricity and low toxicity, and at the same time do not create significant foam and corrosion in during drilling operation. This drilling fluids system's unique chemical structure enables this system to provide multifunctional properties such as surface tension reduction, foam control, and viscosity stabilization, HPHT fluid loss controller.

This new drilling fluids system is formulated by using special HPHT synthetic polymers and specialty additives to reduce HPHT fluid loss of the system and provide maximum shale inhibition in HPHT wells, limitation of foam, and increasing ROP. This system significantly reduced the degradation of polymers and fluid loss additives in WBMs up to 375 °F and increase the rheological and filtration stability to improve the thermal stability in higher temperature environments. Experimental results from the performance of this product have been acceptable in down-hole conditions. This also reduces cost and logistics issue especially in offshore and extend the thermal temperature limitations of standard system components, premium starch derivatives and XC polymers.

In present work, laboratory evaluation of specially-formulated fluids to enhance the properties of the HPHT water based drilling mud was investigated. We put and maintain specialty chemicals in from the beginning operation and we did not experience foaming, ever!
Effects of Injection Pressure on Wellbore Stress Using Flow-Stress Coupling Method
Authors: Bataee Mahmood , Irawan Sonny , Ridha Syahrir , Hematpour Hamed , Hamdi Zakaria
Published: August 2016

Enhanced Oil Recovery (EOR) injection methods are increasingly applied globally as the effective method in oil wells. Fluid injection alters the formation stress around the wellbore. In this study an iterative coupling method is proposed to evaluate wellbore stresses for one cycle of water alternating gas (WAG) injection. The effective parameters such as pressures, temperature, saturations and stresses are obtained for the multiphase flow condition using mathematical modeling. In this study, finite difference method is used to calculate pressure, temperature and saturations; and finite volume method is applied to evaluate stresses. Iterative coupling method is used to improve the accuracy of the results. The results show the pressure is boosted around wellbore after injection and how the water bank is pushed by injected gas. Maximum value of radial stress is obtained in the direction of horizontal maximum in-situ stress. Maximum value of tangential stress is determined in the direction of horizontal minimum in-situ stress. Vertical stress around the wellbore is not related to horizontal maximum and minimum in-situ stresses. The shear stress values are small in comparison with other stress types. The accuracy of model results are increased by iterative coupling, which the maximum correction is about 20 psi (0.14 MPa) for pressure. The developed model is capable to be applied in the wellbore to ensure stability for different injection or production cases.
A Case Study: Field Application of Ultra-High Temperature Fluid in Deep Well
Authors: Liwei Wang , Bo Cai , Xiaohui Qiu , Yongjun Lu , Wen Zhai
Published: August 2016

In this paper, we will introduce the performances, research's process and a case study of ultra-high temperature fracturing fluid. The ultra-high temperature well is a carbonate formation with 205°C, located in HuaBei Oilfield, East China. The temperature of NiuDong carbonate formation is more than 200°C in HuaBei Oilfield in East China, acid-fracturing is an important stimulation for NiuDong reservoir. As known, the guar fracturing fluid is usually used less than 177°C because of guar molecule's performances, so we develop a ultra-high temperature polymer as pad fluid of acid-fracturing to stimulate the NiuDong carbonate, the polymer is a novel structural terpolymers which can be cross-linked by crosslinking agent and broken by APS. The structure of thickener is a key factor to increase the high temperature resistance of polymer, so a novel molecular structural polymer with C-C bond backbones and C=C bond monomers is developed for the ultra-high temperature fluid, and the hydration group with C-C, C-S, C-N is also added in the side chains with the purpose of decreasing the dissolution time of the polymer. An organic zirconium crosslinking agent with amide groups is selected to crosslink the polymer fluid, and the cross-linking time is controlled. After cross-linked, the network structures of gel fluid like the uniformed petals in the scanning electron microscope, so the viscosity is very high. Under the conditions of 200°C, 170s−1 and shearing120 minutes, the residual viscosity is more than 130mPa.s, The evaluated tests show that carrying proppant of polymer fluid are good, low interfacial tension and low residues. The ultra-high temperature polymer fracturing fluid has been successful used in a Well of NiuDong sag. Ultra-high temperature polymer fracturing fluid provides a selection for the formation with more than 200°C.
Successful 20 Well Stimulation Campaign in a Mature Oil Field in Myanmar
Authors: Shaoul J. R. , Tkachuk I. , Chia D. J. , Nyo T.
Published: August 2016

Hydraulic fracturing technology is widely used to facilitate and enhance the recovery process from oil and gas reservoirs. Much worldwide experience has been gained in stimulating conventional and shale oil reservoirs; however achieving good stimulation results in mature (depleted) oilfields with moderate permeability can be challenging and can easily fall below expectations for a variety of reasons.

To narrow the gap between expected results and actual well performance after a successful fracturing treatment it is very important to understand the reservoir characteristics and the actual reservoir potential. Despite the common opinion that stimulating mature, depleted wells is unprofitable, experience shows that stimulating such wells can still result in substantial and profitable production increases.

Twenty hydraulic fracturing treatments performed on wells in a mature onshore oil field wells in Myanmar, in south-east Asia have shown significant increases in initial incremental oil production rate—on average by a factor of two, which was still below the expectations. The treatments have effectively increased cumulative production and arrested exponential decline by +62% per annum. The result is a flatter production profile and has higher sustained oil production rates.

This paper discusses the challenges seen and the results obtained utilizing hydraulic fracture stimulation in a mature oilfield. This case shows the importance of a proper candidate selection method, which has contributed to successful stimulation and improved oil recovery in this case.
Extending Life of Mature Oil Wells with Various Type of Siphon String Application in Offshore North West Java
Authors: Wibowo K. , Widyantoro B. , Kurniawan R. C. , Azizan Y.
Published: August 2016

Offshore North West Java (ONWJ) field has been producing since 1971 with multi-stacked layers, solution gas to weak water drive mechanism, most of wells are completed with dual strings and gas-lifted. This condition compromise a relatively shallow top packer placement. In some cases, abandonment pressure has been reached as characterized by low static liquid level below deepest gas-lift mandrel. Apart from that, tubing integrity is becoming important issue as fields are maturing.

Less operational complexity for the installation of siphon string or velocity string to tackle the two challenges above and better economic returns make it a better option compared to recompletion.

The applied strings are from 1.75″ QT-900 coiled tubing, installed with various configurations of packer, gas-lift mandrel, and length depending upon wellbore completion, artificial-lift concern and well integrity requirement.

Siphon string has been installed in 6 strings; whereby 3 strings with tubing integrity issue (well A, B and C), 3 strings with liquid level below deepest gas-lift injection mandrel (W, Y and Z). After installation, well A and B were flowing for 2 years before they were finally shut-in due to leak below the siphon string assembly. Well C had flowed for another 6 years before it was shut-in. Well X has been flowing since the inception of siphon string in 2006 until this paper is written, well Y has flowed for 8 years and well Z has been flowing for 1 year. An increase of 0.5% – 2% of recovery factors for these wells has created opportunity for other similar wells to continue or increase production.

The first part of the paper will describe on the candidate selection and well configuration, the second part of the part will cover the installation procedures, challenges and lessons learnt. Finally, production results comparison from pre and post installation is presented.
Integrated Holistic Approach to Drill Middle-East Region Sensitive Shales Successfully: Example of Ahmadi, Wara and Middle Burgan Shales in Kuwait
Authors: Khan Ali Nasar , Marie Safaa Mohamad , Gawwad Tarek Abdel , Subbiah Surej Kumar , Tan Chee Phuat , Povstyanova Magdalena
Published: August 2016

Kuwait Oil Company (KOC) was planning further development of the Sabriyah (SA) and Raudhatain (RA) fields by drilling a number of horizontal wells. Both fields presented considerable challenges that included, among other factors, drilling through several problematic shales. The major drilling issues experienced in the shales comprised of tight spots, packs-off, etc. To optimize the drilling process and minimize the risks while penetrating the shales, a decision to conduct a geomechanical study was made. The geomechanical study was focused not only on improvement of the mud weight program (mechanical wellbore stability analysis was conducted) but also on drilling fluid optimization as well.

The drilling fluid optimization analysis was carried out in order to evaluate the potential time-dependent wellbore instability mechanism(s) in the Ahmadi, Wara and Middle Burgan shale formations in the two fields, to define salt concentration for nominated mud types, and to develop solution and strategy to mitigate and/or manage the wellbore instability problems.

Based on the time-dependent shale stability analysis, recommendations were made for drilling the Ahmadi, Wara and Middle Burgan shale formations for water-based mud (WBM) and oil-based mud (OBM). Mud salinities were provided for several combinations of designed mud weight and evaluated breakout mud weight.

The following conclusions were drawn based on the geomechanical study: Water activity of the Ahmadi, Wara and Middle Burgan shale formations was moderately high. Hence, it was feasible to select an optimum drilling fluid design (whereby the mud pressure penetration was fully counteracted by the chemical potential mechanism) for WBM and OBM for the shale formations, even though overbalance pressure in the formations was relatively high. The Ahmadi, Wara and Middle Burgan shale formations could have been drilled using the designed mud weight programme and salinities for the two mud types without significant time-dependent wellbore instability problems in the analyzed planned wells.If the recommendations on mud weight and/or salinities were not fully followed, the shale formations could deteriorate with time due to either mud pressure penetration mechanism being not fully counteracted by chemical potential mechanism or over-dehydration. Increase in drag that could indicate formation deterioration should be established based on drilling parameters and rig capabilities.
Managing BHA Components Integrity with a Fatigue Management Workflow
Authors: Suryadi Hendrik , Li Ke , Brovko Katerina , Parkin Edward , Ossia Sepand
Published: August 2016

BHA integrity is important to successful drilling operations. Fatigue failure is the primary cause of twistoffs. There has been no method to predict and monitor fatigue life of BHA components while drilling. Current preventative methods include predefining the collar life based on past experience and tracking the cumulative pumping hours. When total hours reach the predefined life, the collar is junked. This method is inaccurate because the pumping hours do not accurately reflect the fatigue life of a collar. Regular inspections by nondestructive testing (NDT) to detect any cracks should reveral the initiation of fatigue failure. However, a collar can still consume its fatigue life, initiate a crack, and finally twist off while drilling, causing significant loss of time and money.

Fatigue damage consists of two stages, crack initiation and crack propagation, with crack initiation accounting for most of the total life. Rotating bending is the driving force for fatigue cracking. It induces cyclic stresses and strains at the stress risers, which are the fatigue-critical features. Fatigue data can be presented in the form of M-N curves, where M is the applied bending moment and N is the total life in number of cycles. The BHA bending moment distribution can be computed with a BHA analysis. Given a bending moment, the cyclic stresses and strains at the most critical feature of the most critical BHA component are typically determined with finite element analysis. The life of the most critical feature can then be calculated with the stress-life or strain-life curve of the collar material. This governs the life of the entire BHA.

A fatigue management workflow has been created for planning and execution monitoring phases. During planning, the engineer can calculate the expected fatigue life of the BHA and optimize for the expected duration of the job. The result can be used to select reliable components with sufficient fatigue life for the job. While drilling, this method enables engineer to continuously monitor the consumed fatigue life of any BHA component and make the decision to replace the tool before a failure occurs downhole. After the job, the consumed life can be recorded in the maintenance system to track the remaining life and decide what preventive maintenance is required.

This innovative workflow has been implemented to manage BHA integrity for medium to high dogleg severity (DLS). The approach to managing fatigue life enables risk mitigation for BHA integrity, pushing kickoffs deeper, shortening the curved sections, and increasing reservoir exposure, including reentry applications. Field cases have proven that the solution provides engineers with a new tool to reduce fatigue failures by predicting expected fatigue life consumed on a job, selecting correct tools, and proactively managing the drilling risks.
Tailored Innovative Bit Technologies Lead to Significant Cost Saving and Performance Improvement in the Ultra-Deep Formation of Tarim Basin in West China
Authors: Teng Xueqing , Zhao Liang , Xu Zhixiong , Cheng Xiaomin , Li Ning , Chen Demin , Feng Shaobo , Zhou Bo , Yang Xiongwen , Zhang Tao , Liu Yu
Published: August 2016

For the ultra-deep ultra-high pressure wells in the Kuqa foreland basin of the Tarim basin in western China, it has been an ongoing challenge for more than a decade to drill through the Cretaceous Bashijiqike (K1bs) formation in a more efficient and economical manner. It is comprised of sandstone and mudstone with abundant natural fractures in the upper K1bs with frequent severe fluid loss occurrence and middle and bottom K1bs are both comprised of highly compacted sandstone, mudstone and siltstone without the presence of natural fractures. In the past, it requires an average of 8, and sometimes up to 16, premium PDC bits and more than 90 days to complete the target interval. This paper discusses the continuous effort in the development and introduction of ongoing bit technologies to drill through the Bashijiqike Formation and the development of methodology that tailors different bit technologies to different sections of the Bashijiqike formation according to drillability characteristics. Dissecting the formation into different sub-zones and matching them with suitable bit technologies results desirable efficiency and significant cost reduction.
BHA Modeling and Application of Bi-Center Bit with Unique Vibration Dampening Tool to Improve Hole Opening Performance in Offshore HTHP Exploratory Well in Krishna Godavari Basin, India
Authors: Lobo Monali , Agarwal Chakshu , Sharma Deepak , Lang Clifford , Brickell Nigel , Pathak Mandar , Chakraborty Biswajit
Published: August 2016

In a technically challenging & high cost environment such as HTHP wells, careful selection and adoption of advanced technologies for the successful completion of the well is paramount. As per the original well design of the subject well, it was planned to drill with a bit & under reamer which was actuated by a ball drop mechanism. This led to the restriction of placing the under reamer close to the bit as MWD/LWD had limited pass through & hence the under reamer had to be run above the tools leaving approximately 25-30 m of rat hole un-opened along with inability to retrieve radioactive source in an event the BHA was lost in hole. This required two separate BHA runs to open the rat hole in order to place the casing shoe as deep as possible. The additional hole opening trip would have resulted in extra time and hence additional cost, moreover it was prudent in HTHP well to place the casing shoe exactly at right depth to achieve well objectives. Hence, use of Bi-center bit to simultaneously drill & under ream without any pass through restriction was evaluated.

Several critical issues, related to application and BHA design, were faced by the Well Engineering team. Reaming while Drilling (RWD) with bi-center bits has always been challenging in terms of vibration-related inefficiencies. Due to the asymmetrical geometry of the bit, imbalances in force and mass have been responsible for the vibration related problems. Secondly, due to the minimum pass through requirements, these assemblies are virtually always run with under-gauged stabilizers as it allows a certain degree of lateral movement within the constraints of the enlarged hole.

All of these issues could have caused the pilot-bit drilling an over-gauged hole along its axis which results in the bit drilling off center giving an overall under-gauged hole as the pilot of the bit is not centralizing the reamer. A unique eccentric vibration dampening tool (ideally located in the string) was used to mitigate the drillstring vibration & bit whirl. This paper describes the well specific BHA design & placement of the vibration dampening tool used to improve hole opening performance. A total of 4 bi-center bit runs over three hole sections & different sizes i.e.12.¼″× 14.¾″, 10.3/8″ × 12.¼″ & 5.7/8″ × 6.¾″ are also discussed in the paper.

Unusual problems were encountered while drilling shoe track & landing collar for liners in 10.3/8″ × 12.¼″ and 5.7/8″ × 6.¾″ hole section. Lessons learnt, recommendations & contingencies to be planned for successful application of bi-center bit are discussed.
Dare to Change: An Approach to Implement Enterprise Level of Real Time Well Solution for Collaborative Working Environment
Authors: Mohamad Azlan , Yusoff Noorazmah , Aris Sazalee , Bismo Dismas , Regan Matt
Published: August 2016

Petroliam Nasional Berhad (PETRONAS) has long realized the importance of real-time drilling data. The company utilizes the technology to monitor rig site operations. An in-house real-time surveillance-monitoring centre, called the Smart Drilling Optimization Monitoring Centre (Smart DOMC), was established in 2010 within the company’s headquarters. The centre’s real-time environment was fully managed by a single service-company: data aggregated on the rig site was kept in the service company’s server, in the service company’s proprietary format, and only accessible to the drilling engineering team via the service company’s web-based application. This approach forced PETRONAS to be wholly reliant on the service-company’s own technical application and service, with no ownership or control of (the company’s) real-time data architectures, and only nominal visibility of dataflow and management.

In line with the company’s Integrated Operations (IO) initiative and driven by the company’s increasing amount of operations, the availability of a standardized independent real-time data management infrastructure became a critical component in order to facilitate seamless flow of real-time technical data transparently throughout the organization, particularly within the Smart DOMC and the operation team’s disbursed workplaces.

Thus, in 2014, the Real Time Well Solution was implemented. The new solution is an enterprise real-time data management solution with web-based delivery, which leverages the Wellsite Information Transfer Standard Markup Language (WITSML) as the standard format for the exchange of data. It is a secure infrastructure wholly resident within PETRONAS IT environment, which consists of clustered database servers with load balancing and failover backup servers ensuring high-availability, and capable of facilitating the flow of real-time drilling data from multiple rig sites, for the company’s domestic and international operations. It offers advanced customizable web-based features for domain experts to view real-time drilling data, through the standard web-browser and mobile devices.

This paper will describe PETRONAS Real Time Well Solution and the three main challenges faced in implementing the new solution. Four case histories detailing the utilization of the WITSML infrastructure during critical well construction operations will also be reviewed. With the new System, PETRONAS is able to implement industry-accepted and non-proprietary standard in accessing real-time information, take immediate ownership and better control of data aggregated on rig sites, and integrate real-time information with existing corporate third-party applications.
Risk Impact Analysis Maximises Safety, Efficiency & Drilling Cost Effectiveness: Vital in Today's Oil Price Era
Authors: Gibson Michael
Published: August 2016

With most of the world’s ‘easy play’ oil and gas fields having been found and now being produced, Operators have little choice in many cases but to drill in more and more difficult conditions in order to produce the oil and gas which the world demands. This increase in difficulty is further compounded by a very low oil price these past 18 months (2014 – 2016) which means that every effort must be made to reduce not only the cost of drilling itself but also to ensure that no untoward event occurs such as a blowout.

This paper describes a very significant drilling success story completed in Europe (UK North Sea) which has direct applicability to South East Asian Operators & Drilling Contractors. By carrying-out effective Risk Analysis this difficult well was drilled successfully & economically.