bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial Huff and Puff Project at Mangunjaya Field Wells: The First in Indonesia Towards Successful MEOR Implementation
Authors: Ariadji T. , Astuti D. I. , Aditiawati P. , Purwasena I. A. , Persada G. P. , Soeparmono M. R. , Amirudin N. H. , Ananggadipa A. A. , Sasongko S. Y. , Abqory M. H. , Ardianto R. N. , Subiantoro E. , Aditya G. H.
Published: October 2017

This multidisciplinary paper presents microbial Huff and Puff project results with objectives: 1) to understand the mechanisms through relating laboratory work results, field implementations and a history matching process during reservoir simulation (2) to seek reliability of the microbial Huff &Puff based on improvements of the production performance parameters. After a thorough screening work was done, detail laboratory works produced fluid samples from selected wells was conducted, implementation programs were designed, and a set of equipment consisting of a cultivation tank, a mobile laboratory, and other supporting facilities was installed at the field. The implementation basically involves three stages: (1) preflush, cultivation solution, and post flush (2) injection of cultivation solution and post flush, and (3) injection post flush. Finally, this project conducted a 6-month monitoring program of microbe population and compositional analysis of the produced fluid samples, and production performance analysis of wells production data. The overall growth of bacteria had increased from 2×103 CFU / mL to 5×106 for 176 days in Well MJ122, on the other hand, Well MJ-125 can reach much higher up to 500×106 bacteria (CFU/ml) in 122 days. Using the GC/MS composition analysis for semi-quantitative analysis with standards internal reference marker ratio of Pr/Ph shows monthly biodegradation samples percentage before and after application up to about 34% at the 3rd month of monitoring. The well MJ-125 Structure Analysis of Bacteria Community resulted from Single Strand Conformation Polymorphism (SSCP) Method indicated that the number of Operational Taxonomy Unit (OTU) change during the production was relatively stable and this correspond to their Sorensen Index values. But, MJ-122 well indicated unstable community structure, however, the interaction between microbes which were injected with indigenous microbes was not competitive. The wells water cut versus gross rate profiles show that the MJ-122 water cut drop occurs at low production rate, whereas, the MJ-125 water cut drop occurs drastically both in low and high production rates. The well MJ-125 average oil rate gain is about 20%. However, both wells show peculiar production profiles by depicting a cycle of "a valley of low values". Finally, a history matching process supports understanding of the mechanisms.
Extending Life of Liquid Loaded Gas Wells Using Velocity String Application: Case Study & Candidate Selection
Authors: Andrianata Satria , Allo Keken Rante , Lukman Ade , Kramadibrata Ari Taufiq
Published: October 2017

Depletion of the reservoir leads to a decrease in production rate and continuously drops below its minimum critical velocity. At this point, the liquid which flows vertically upward with gas begins to fall back into the wellbore. Liquids accumulation in the tubing creates additional pressure drop and gives more flow restriction to surface. Smaller diameter tubing string (so-called, velocity string) installation is a simple yet successful methods applied in Semberah field to overcome liquid accumulation in wellbore of low production critical gas wells. This paper discussed case studies and screening improvement of velocity strings installation in the observed field. The project delivered an improvement of candidate screening and design to achieve the continuously flow after installation. Case studies were introduced in this paper as example of success and non-success application. Screening improvement was delivered based on post-mortem analysis. Selection candidate included identification of liquid loading symptom by well behavior, critical rate analysis on each wellbore section, and flow regime analysis. Pressure and temperature bottom-hole survey, either at static or flowing condition had to be provided and matched with velocity string model. Evaluation of new critical rate each wellbore section and new flow regime after installation must be calculated. This applied method was proven to extend production life and increase gas cumulative production in observed field. Better understanding of comprehensive well screening is an important factor to enhance success ratio of velocity string installation project. The improved screening based on field experiences can be used as a reference of velocity string selection candidate and design in other liquid loaded gas field. This paper also discussed further opportunities of un-success cases, which apply a tandem de-liquefaction technology: velocity string and wellhead compressor or gas lifted injection for gas well.
Integrated Stress Calibration by Utilizing Advanced Acoustic Information - A Case Study from Deepwater Malaysia
Authors: Heidari Babak , Millot Pascal , Chujo Kota , Watanabe Yoshiaki , Yoshiyama Tomoyuki
Published: October 2017

"Block X," located in offshore Sabah is operated by JX Nippon Oil & Gas Exploration (Deepwater Sabah) Limited., which had drilled several exploration wells and acquired extensive wireline and LWD information to evaluate the block for further exploration and future development. Drilling exploration wells in a deepwater environment can lead to drilling difficulties. For example, a very narrow safe mud weight window was encountered in the discovery Well X and subsequent drilling difficulties delayed the well delivery. In orderto minimize the drilling risk for upcoming prospects, detailed petrophysical, geological and geomechanical studies have been conducted based on extensive evaluation of wireline and LWD data.

Determination of horizontal stress directions and magnitudes are an important part of building the 1D mechanical earth model, which allows optimizing perforation and completion design, and production planning. Knowledge of the stress directions also helps to optimize well trajectory design so that wellbore instability can be minimized. Several methods for identifying stress directions are available and investigated, including borehole breakout orientation and shear sonic anisotropy information. For complementing the existing drilling data (leak-off and formation integrity tests), the horizontal stress magnitudes are determined using the dipole radial profiles and the sonic anisotropy using acoustoelasticity theory.

The variation in shear sonic slowness within the elastic region of the rock is compared to the stress distribution caused by the presence of the wellbore. The relationship between shear slowness (modulus) and stress is then established to provide the acoustoelastic coefficient and horizontal stress magnitudes (both minimum and maximum) are then determined. These results were used to reduce uncertainty in the state of stress, and used in optimizing the wellbore trajectories for future development wells.

In the current study, besides conventional stress calibration data such as LOT/FIT and calliper information, advanced sonic information helped to calibrate further the stress profile, which resulted in a comprehensive understanding of the stress regime of the study area. These results are utilized to better design the mud weight program for the drilling of future Deepwater prospects in Block X.
Reservoir Rock Typing for Sweet Spot Identification within Complex Clastic Reservoir: A Success-Story from Northwest China
Authors: Wan B. , Jiang B. , Meng X. , Li S. , Yang Y. , Gong H. , Zhao H. , Wang W. , Wei G. , Zhuang X.
Published: October 2017

The studied reservoir is represented by complex clastic deposits located in northwest of China. From the core description, there are 15 rock types and five oil bearing gradesvarying from no oily to oil immersion. So the reservoir is very heterogeneous and it is very challenging to identify the best zones for fracturing. To mitigate this challenge, it is of utmost important to understand and evaluate the relationship between reservoir heterogeneity and oil saturation level to find out the best reservoir rock type for further completion work.

At the beginning of the work, detailed analysis have been done and a very strong relationship is observed between core grain sizes and oil bearing grade. In the current study area, high resolution borehole image logs are acquired but core data is available only for short intervals. Consequently, borehole image based methodology has been developed to characterize relationship among grain size, sorting and oil saturation. Also, Reservoir Rock Type (RRT) has been computed using integrated result from shale content, effective porosity and image derived advance outputs to identify sweet zone for hydraulic fracturing.

The study shows very interesting results from integrated image analysis within sandy interval, with decreasing grain size the oil bearing grade is increasing and the oil bearing grade is maximum in the medium grain sized pebbly zone. Four main reservoir rock type has been computed from clay content, effective porosity curves and image derived sorting index data. RRT result shows very good relationship with the oil bearing grade. Good RRT is dominated with oil immersion, Good to Moderate RRT is dominated with oil spot, Moderate RRT is dominated with oil stains and Poor RRT is dominated with no oily.

This RRT computation method from image derived high resolution data provides very valuable information for proper evaluation of this complex reservoir and sweet spot identification. This workflow has been established as a standard workflow to be applied in other parts of the study area. Also, this work can be a very good example to follow in similar complex clastic reservoirs from any part of the world.
Corrosion Under Insulation CUI Management on Idle LNG Process Train
Authors: Haga Gren
Published: October 2017

Badak LNG was capable to operate eight LNG Process Trains to produce LNG with maximum annual capacity of 22.5 MTPA. However, Badak LNG is currently entering idle phase for several of process trains due to declining of feed gas supply. Long Term Idle (LTI) preservation program has been developed to maintain the condition of all plants including insulation removal for all insulated lines and equipment. Insulation removal program is intended to reduce risk of Corrosion Under Insulation (CUI) that may attack all insulated lines and equipment.

Unfortunately, due to cost effectiveness program, insulation removal has been postponed and evaluation was needed to understand the severity of CUI and its effect to material integrity and cost benefit that maybe generated from this postponement. Therefore, evaluation of CUI severity was conducted during 5 years of idle period by using visual observation on selected inspection windows to determine the severity. Thickness measurement for the worst CUI grade items was also performed in the end of idle period to find out the effect of CUI degradation to integrity of material.

The evaluation reveals that about 21 percents of all inspected pipings and equipment were actually degraded in term of corrosion grade after 5 years in idlecondition. However, no degradation into grade D (worst grade) from grade A and B items was observed. Thickness measurement on worst grade items shows that the degradation of CUI is not affecting the material integrity significantly. Recommendation might be given in the future to exclude better condition, such as grade A and grade Bfindings from insulation removal programwhile removal still has to be conducted for worse grade items (grade C and grade D).
WAG Cycle Dependent Hysteresis Modelling through an Integrated Approach from Laboratory to Field Scale, Malaysia Oil Fields
Authors: Belazreg Lazreg , Raub M Razib , Hanifah M Azri , Ghadami Nader
Published: October 2017

With the increasing demand in domestic energy requirement and with declining production rates from mature fields of offshore Malaysia, PETRONAS has embarked on an aggressive campaign to address the decline in rates as well as increase the reserves through proven Enhanced Oil Recovery (EOR) application. An immiscible Water Alternating Gas (WAG) process is found to be the most favorable EOR method due to gas supply availability, proven world-wide application, and promising results in improving injection fluid sweep efficiency and reducing residual oil saturation.

To reduce the uncertainty of EOR technical studies under low oil price, a comprehensive integrated procedure is required to study WAG performance and define key factors that impact flow efficiency under three-phase flow conditions for a more representative full-field reservoir simulation study results.

This procedure involves a detailed comprehensive parametric study of the cycle dependent hysteresis starting from extensive literature review, followed by laboratory experiments and extracting pertinent WAG parameters from coreflood history matching and finally applying these parameters in full-field reservoir simulation study. This study demonstrated that the WAG cycle dependency of relative permeability during WAG process is one of the key factors that has significant impact on WAG performance and recovery factor. This feature cannot be captured by conventional three-phase flow models used by reservoir simulators. The study indicates additional recovery factor of about 1%-2% compared to the base-case WAG model without WAG hysteresis.
An Analytical Approach for Evaluating the Capillary Trapping during CO2 Storage in Aquifers
Authors: Zhu Langtao , Liao Xinwei , Chen Zhiming , Mu Lingyu , Wang Tianyi
Published: October 2017

Geological storage of CO2 in saline formations is employed as a key emissions reduction method in the global effort to mitigate against climate change. There has been significantly development of numerical and simple analytical techniques to support screening analysis and performance assessment for potential carbon sequestration sites. However, these techiniques had ignored the capillary trapping mechanism which has been shown as the fastest mode of trapping.

In this work, we focused on the capillary trapping phenomenon occurring during the gas alternating water (GAW) injection and developed a new analytical method to predict the potential of capillary storage. Firstly, based on the fractional theory and considering the effect of mutual solubility between CO2 and aqueous phase, the saturation profile of two-phase flow is acquired. And the drainage and imbibition phenomenon are applied to simulate the capillary trapping mechanism. Then, accoring to the saturation profile, the analytical method for estimating the capillary trapping capacity of GAW is proposed. Finally, this new analytical model is applied in a real case to estimate the capillary trapping capacity, and the sensitivity analysis of some important parameters is also conducted.

The results of this work show that the capillary trapping of subsequent gas injection occupied about 5.77%, which could not be ignored in estimating the capillary trapping potential. In addition, results of sensitive analysis show that higher residual gas saturation would lead to higher capillary trapping capacity. And higher retardation factor would lead to higher capillary trapping capacity of subsequent gas and water injection, which illustrated that the mutual solubility between water and gas is important to the capillary storage potential.

This work further developed and improved the accuracy of our previous method in estimating the capillary trapping capacity. And it also provides a new idea for evaluating the potential of capillary sequestration.
Enhanced History Matching and Prediction Using Integrated Analytical and Numerical Modeling Approach
Authors: Ghadami Nader , Benayad Nourreddine , Motaei Eghbal , Raub M Razib
Published: October 2017

Integrated reservoir modeling with representative data is crucial for an effective reservoir management and depletion plan. Both analytical and numerical approaches benefit from this integrated process. The objective of this study is to incorporate the outcomes of analytical techniques such as rate transient analysis (RTA) and pressure transient analysis (PTA) into numerical reservoir model to have a better understanding of drive mechanisms, reservoir connectivity with minimal time-consuming for history matching efforts but a more reliable production forecast.

In order to demonstrate the methodology, a clastic reservoir from Malay basin was considered. Sedimentology and sequence stratigraphy studies were performed to have a better picture of heterogeneity and zonation of the reservoir. All production and injection data were investigated along with pressure data to filter data inconsistency. Shut-in time should be long enough to take representative reservoir pressure and accordingly material balance study conducted for accessible volume for a given area. However, flowing material balance is able to be applied with no restriction on the production data for evaluation of historical data and prediction cases.

The boundary of the channel sand was constructed based on the well log data and seismic attributes. Amplitude impedance was used as a guide for lithofacies and porosity distribution in the geological model. In addition, stratigraphy definition with further details were incorporated. Lithofacies, petrophysical and SCAL data were incorporated in rock-type classification and accordingly saturation-height-function were modelled. Analytical approaches including PTA, material balance, and RTA were utilized to have a better understanding of fluid flow and drive mechanisms. The well and reservoir properties and also connected volume from analytical approaches were utilized as a tuning tool of static model. This approach considerably reduced the iteration between static and dynamic models for history matching exercise. Afterwards, the production forecast were conducted with two development opportunities identified.

In this study, an integrated methodology was applied to mitigate the complexity of history matching task. Moreover, it is demonstrated that using such analytical methods help to improve the development plan of a given field significantly.
Dynamic Analysis of Surface Casing During Assembling and Installation
Authors: Yamamoto Marcio , Takagi Ken , Wada Ryota , Agostini Cristiano , Malta Edgard B.
Published: October 2017

During the assembling and installation of a surface casing into a subsea well, the casing string is hanged by its top end and free to move at the bottom end. The floating platform motions generates dynamic loads on the whole string. In this article, we assess the dynamic stresses along the surface casing using a commercial software for riser analysis. Three 20" surface casing strings with different lengths (400 m, 731 m, and 1036 m) were used as model for numerical simulation. The results show that, at the top and middle parts of string, the main component of the Von Mises stress is the axial tension; and the lower part of casing has the bending stress as the main component. Further, the effective tension results show that, for the shortest casing, axial compression may occur. Despite, such dynamic stresses are relative low compared yield stress of the material, the prolonged action of such dynamics loads may result in fail of connectors or other components.
Enhancing Well Construction for More Efficient Well Abandonment
Authors: Dahmani L. , Hynes L.
Published: October 2017

The lack of planning for well plug and abandonment (P&A) during the well-construction phase can significantly contribute to the extended operational time and associated high cost of P&A. The impact on time and cost is mainly due to insufficient well data, uncertain casing cement integrity, and lack of information on competent formation for permanent barrier placement. Undocumented pressure and stress evolution, and well events also can contribute to increased time and cost of P&A.

Although new technologies can reduce plug and abandonment cost, another approach is to effectively plan for well abandonment during the front end engineering design (FEED) and well-construction phases and during drilling of new wells.

This paper examines recommendations for improvement and requirements that should be addressed by the industry, regulators, and operators to introduce clear well-abandonment requirements into FEED and well-construction phases for new drilled wells. –Requirement for planning for well integrity for the entire well life cycle of the well from well construction to well abandonment and after well abandonment–Identify number and position of required barriers for abandonments–Requirement to identify and document competent formation during well-construction phase–Requirement to demonstrate there is cement with good bond / isolation between the casing and the formation in the areas where internal cement plugs are to be set.–Qualification of the formation as possible well barrier–Well monitoring: consider introducing sensors or instrument in cement (cement behind casing) to continuously monitor and track any pressure build-up in the casing annulus.–Completion design: Avoid control lines at the intended well-barrier depth(s) and install production packer(s) in a location enables through-tubing well-abandonment methodologies.

Other considerations to be addressed in this paper are the change of regulations between the time the well is constructed, and its final P&A.

The novelty of addressing well abandonment requirements in the FEED and well-construction phases will significantly simplify the abandonment phase reducing risks and cost while improving well barrier integrity.
Redevelopment of Mature Combination Drive Reservoir to Enhance Ultimate Recovery in Asri Basin, Indonesia
Authors: Widiatmo R. , Waskito L. B. , Afi F. N. , Nugroho P. , Gunawan H.
Published: October 2017

The 34-X sand is a solitary sand reservoir and locally sinuous sandstone body. This reservoir is displaced by major normal fault zone known as the Widuri Fault that divided in two contrast areas of 34-X facies and production characteristic. The objective of this paper is to present how the combination drive reservoir redevelopment project was planned, extensive evaluation process has been made, and successful cases in enhancing reservoir ultimate recovery. The solution for this title is multi-disciplinary approach to create sharp analysis. The first step is numerical calculations of material balance to determine oil-in-place in a reservoir and to predict the future performance, this phase is tricky due to multi-driving mechanism reservoir behavior, therefore material balance analysis need to be supported by deep sub-surface analysis in property distribution on second step. This part simultaneous inversion, 4D timelapse seismic and sweep pattern analysis have been done to get comprehensive interpretation of reservoir characterization and reservoir connectivity monitoring. The third phase is supporting analysis by tracer injection, we implement tracer in several wells to ensure connectivity of the reservoir, and to evaluate injection performance. The last phase is technical difficulties in operation area, complex reservoir evidently cause complex operation difficulties, sand problem, formation damage, tubing leak, water out, plug-up injector well, etc. are problems we have to deal with. From reservoir pressure data distribution, surface gas-oil ratio, water production, and well behavior concludes that 34-X is combination drive reservoir (water drive-solution gas drive) and based on fault analysis we divided into two areas east and west, 34-X West area sandstone body is straight, with approximately 100-300m wide and 8m thick. The western part water cut is over 90%, this indicates the conduits for preferential water flow has established. From material balance calculation OOIP estimated 16.3 MMSTB. The eastern part of the 34-X sand appears to be isolated from western portion of the channel by a fault with a throw of 90 feet. The eastern portion of the widuri field is influenced by a partial water drive, indicated by high water cut histories. However the water drive is weak, the average pressure has declined to 520 psi, estimated OOIP 56.2 MMSTP. Before the redevelopment project recovery factor is 22%, and increase significantly to 27.4% simultaneously with oil production rate increase up to 40%. Dominantly pressure-depletion drive during hydrocarbon production in 34-X sand in west area occur since that area provide poor connection to an aquifer and for east area of Widuri Fault condition is limited aquifer. The water cut of production in 34-X sand well varies across the axis of the sandstone body, it caused by controlled by internal heteroginity.
The Integrated Environment for Real-Time Decisions: Delivering Excellence in Brunei Drilling Operations
Authors: Rowe Shawn , Keasberry Shawn , Hunt Jeffrey , Arias Alex
Published: October 2017

Hydrocarbon exploration in Brunei has resulted in sophisticated drilling projects highly dependent on integrated environments, real-time decisions, and top-class drilling engineering. During peak activity in 2011 and 2012, an operator faced a declining performance in well construction projects caused by well-related drilling issues in extended reach drilling (ERD), snake, fishhook wells, leading to an unnecessary increase of total well costs.

Managing the previously mentioned risks to reduce non-productive time (NPT) was the main driver for building an integrated environment for real-time decisions (IERTD), a new concept to optimize drilling operations by facilitating the decision-making process while maximizing the value of historical and real-time data. The pre-existing real-time operation center was integrated into the operator's performance process where all workflows were redesigned to help ensure focus on cross-department value, risk mitigation and real-time interventions, instead of reporting and low-value interventions. Novel and innovative application of monitoring software technology helped align well teams to actual versus plan engineering models, helping ensure faster and reliable data analysis, providing teams better visibility of well status, allowing improved decision making.

Two years after the implementation of the IERTD, the operator experienced a reduction by 10 times in terms of leaving a bottomhole assembly (BHA) in the hole. The number of stuck pipe events was reduced by 67%, by improving the quality of information for decision makers and controlling the risk associated with the well challenges. The last 36 wells (included in this study) were drilled with zero NPT associated with drilling dynamics. The operation significantly benefited from the continuous flow of reliable and accurate processed information that allowed every final user to dispose the adequate tools to respond on time.

This paper illustrates the techniques, technologies, and fundamentals behind the successful operation of the IERTD and how the interaction of these innovative concepts may contribute to operational excellence in future drilling projects.
Economic Comparison of Hydrocarbon Recovery under Injection of Different Polymers
Authors: Cenk Temizel , Dike Putra , Henny Anggraini , Raul Moreno
Published: October 2017

Injection of water in waterflooding operations provides pressure support and displaces oil in the reservoir, thereby improving the recovery factor. A factor of significant importance in this process is mobility ratio; a higher mobility ratio allows for better displacement of oil by the injected water. For further increasing the volume of reservoir swept, gelling agents are used to improve the mobility ratio of injected water. It is imperative to identify the right type and amount of viscosity reducer to be used since shear stress and high temperatures cause polymer degradation, due to which polymer macromolecules may be forced into narrow channels.

Performance of xanthan and synthetic polymers in a polymer injection process were compared. The model is assumption is that reduced gel kinetics forms a microgel without redox catalysis. For modeling purposes, a commercial reservoir simulator coupled with an optimization tool was used. The reservoir was modelled having 6 layers for injection, where first 4 layers have high horizontal permeabilities and the bottom 2 layers have a high permeability streak. For the first 450 days, injection water was continuously pumpedinto all layers andin the next 150 daysgel systems were injected only into the bottom 2 layers followed by which water was continuously injected for a period of 4 years. The optimization tool was used for sensitivity analysis investigation of variables to reduce variable uncertainty.

Per modelling results, gel penetrated deep in reservoir but in bottom layers there was blocking. In terms of viscosity effects, the relative benefits of biopolymers and xanthan polymer were highlighted in the sensitivity analysis. Also, this investigation indicated merits of synthetic PAM in terms of resistance factor, insitu gelation treatments and their crossflow dependence. Retention of polymer-gel and their adsorption were shown to be dependent on permeability.

In this study, for comparative purposes, different viscosity reduction treatments were modelled in the same model reservoir to highlight their relative advantages. Also, investigation of control variables through sensitivity analysis outlined the significance of each towards displacement efficiency. Keeping in mind the wide spectrum of areas around the globe where gel solutions can be applied, this study highlights factors that are critical to optimal reservoir management.
Using Business Intelligent Tool to Gain Insight into Well Integrity, Surveillance and Production Data
Authors: Haris Hamzah M , Hui Nicholas Foo , Ismail W Rokiah , Zulkifli Shahrul Anwar , Redzuan Sdn Bhd. , Zahid Ahmad Syafiq
Published: October 2017

The main goal in well integrity management is to ensure integrity of the well is designed, achieved, monitored and maintained throughout the life cycle of the well. In PETRONAS, the status of the well integrity is closely monitored by Subsurface Team. One of the important aspects of monitoring and maintenance of the well integrity is to have a reliable data management system that able to automate all the processes from data storage until data utilization stage. The system should be developed in such a way it follows the organization business workflows hence it will be fitted to increase the efficiency in managing well integrity. The process of transforming operational data into a form best suited visuals for analysis and reporting is essential to extract valuable insight from various datasets.

Since most of the well data are resided in various sources such as different type of database, servers, local workstations etc., it will generate another level of complexity if traditional way of data mining is being practices, i.e. using excel spreadsheet to analyse large and varied data sets. Thus, Business Intelligent (BI) concept is adapted to simplify the automation of data mining and transformation of the data to knowledge.

Web-Based Application, "Well Workbench of Asset Repository (WellWAR)" has been developed for SKG (SKG) Subsurface Team with the above intention. In general, WellWAR will automate some part of data lifecycle processes, that include but not limited to; data entry, data mining, interactive visualization, analytic and reporting. At the current stage, there are well construction parameters, well integrity, idle well, well's budget, surveillance data, technical potential and general reservoir parameters which are all have been integrated into the application. This significantly enhanced existing well data and well integrity management as WellWAR has centralized most of well data information at one place.

This paper will demonstrate on how BI concept can be utilized to produce the more insightful report in making business or operational decision by integrating various dataset that related to well integrity. In terms of functionality, the flexibility to filter with the feature of a responsive visual gives another level of experience while exploring the data, especially when investigating the impact of well's technical potential in relation to unhealthy, idle well status and condition of the wells.
The Reversible Emulsion Controlled by Inorganic Salt at High Temperature or Low Permeability Reservoir
Authors: Ren Jinheng , Wang Yanling , Jin Jiafeng , Wang Kun , Guo Baoyu , Wang Xudong
Published: October 2017

Due to the significant difference of water-in-oil emulsion and oil-in-water emulsion in viscosity, conductivity, rheology, thermal resistance, emulsion system has been widely used in the development of oil fields. The reversible phase inversion technique can enhance the performance of emulsified working liquids during the transportation of fluids in porous media. The objective of this study is to study the preparation and the application of the reversible emulsion controlled by inorganic salts.

SDBS, SDS, and SPS were used as emulsifiers in this study. The white oil and deionized water were emulsified into anoil-in-water emulsion by high-speed stirring. Multivalent metal cations were added to the emulsion to control the inversion of the emulsion to water-in-oil type. Then, the multivalent metal cations were removed by anions, leading to the emulsion reversed from water-in-oil to oil-in-water type. The stability of emulsions was evaluated by the stratification time, thermal resistance, conductivity, emulsion-breaking voltage and microstructure.

The results showed that emulsion's dehydration rate was 8.1% at 25°C, which increased to 14.3% as the temperature reached 90°C after 5 hours. The average diameter of droplets was about 6 μm and conductivity was about 619 μs·cm−1. The emulsion processed by CrCl3·6H2O solution inverted to water-in-oil type, and its oil separation rate was 11.9% at 25°C and 18.2% at 90°C after 5 hours. The emulsion-breaking voltage and average diameter of droplets were 153 V and 13 μm, respectively. After Cr3+ was removed by Na2CO3 solution, the type of emulsion became oil-in-water againand the dehydration rate of this emulsion increased from 3.2% to 5.8% when the temperature reached up to 90°C. Under this circumstance, the average diameter of droplets was 5 μm and conductivity was 1907 μs·cm−1. The emulsion was of high stability before and after inversion.

The emulsion controlled by inorganic salts can be reversed between oil-in-water and water-in-oil type efficiently, which can be used as emulsifier within drilling fluid in the low-permeability reservoir. The characteristics of reversible emulsion drilling fluid include inhibition for shale rock, good lubricity, thermal stability, and excellent cementing quality.
A Workflow from Seismic to Forecast for Tight-Oil Reservoir Development Using a Semianalytical Well-Testing Model with Boundary Element Method
Authors: Chen Zhiming , Liao Xinwei , Zang Jiali , Zhao Xiaoliang , Peng Kewen , Wang Shaoping , Yu Wei
Published: October 2017

Treatments of stimulated reservoir volume (SRV) have been the most effective techniques to enhance well productivity in unconventional plays, like tight-oil reservoirs. Unlike conventional reservoirs, the work in unconventional plays needs to focus on the SRV scale rather than field scale, which requires an integration of many techniques to properly evaluate the SRV properties. Unfortunately, there still lacks of a comprehensive integration of seismic, models, and data for SRV, although much work has been done for fracturing estimations and performance predictions of wells with SRV. To narrow the gap, this paper presents a comprehensive seismic-forecast workflow for tight-oil reservoir development on the SRV scale. The workflow is an integration of microseismic data, well testing interpretation, rate normalized pressure (RNP) interpretation, and numerical production history match. Its contents are described as the following steps: (1) introducing the technique of microseismic monitoring (MSM) and proposing a corresponding simplified SRV model, (2) developing and verifying its well-testing model with boundary element method (BEM), integral method, and superposition principle, (3) discussing the rate normalized pressure (RNP) model of SRV, (4) building a numerical SRV model, and (5) demonstrating the workflow by a field case from Junggar Basin. This paper paves a good way to evaluate well performance and improve future completions in tight-oil reservoirs.
Understanding Shale Petrophysics Helps in Drilling Stable Boreholes: Case Studies
Authors: Al-Arfaj Mohammed , Al-Kharaa Hamad
Published: October 2017

Drilling stable boreholes in shale formations can be a very challenging task when water-based drilling fluids are used. The interactions between water phase in drilling fluids with shale rocks cause different drilling problems such as shale swelling and dispersion. The extent to which a shale sample swells or disperses depends on the clay content of the shale. Some types of clay have more swelling tendency while others have more dispersion tendency. Therefore, identifying the type of clay present in a shale rock is very important for developing drilling fluids capable of mitigating shale drilling problems.

Gama ray data is a powerful tool to predict the clay mineralogy, determine shale reactivity and, as a result, predict the rock response when contacted by drilling fluids. Using petrophysical properties to characterize shale can help determine the appropriate drilling fluid and shale inhibitor to be used. The spectral gamma ray log has been used to determine the proportion of the radiation coming from potassium, uranium and thorium. The ratio of K/Th is utilized to identify clay mineralogy for different shale formations. In addition, formation density log data was utilized with neutron log to give more accurate information about lithology.

The objective of this study is to discuss how petrophysics data of shale formations can be utilized to improve and optimize drilling practices to achieve the ultimate goal of enhanced wellbore stability. Depending on clay content, different shale formations have different responses when exposed to drilling fluids and, therefore, it is of high importance to characterize the shale formation to develop the appropriate drilling fluid.
Characterising the Dependence of Coal Permeability to Methane Adsorption, Pore Pressure and Stress: Laboratory Testing of Walloon Coals from the Surat Basin
Authors: Bottomley W. , Furniss J. P. , Raza Shabbar Syed , Ge Lei , Rudolph Victor
Published: October 2017

This paper discusses a set of laboratory experiments on coal core samples, which seek to understand the changes in coal fracture permeability with varying confining stress, pore pressure and methane adsorption. Currently, no measurements exist to support QGC'sSurat Basin Coal Seam Gas (CSG) development, and therefore themagnitude of change in permeability relative to initial conditions is unknown.

The set of experiments described here use a flow apparatus to measure the permeability of coal core samples as a single variable is changed. The ability to control the laboratory test to separate out the different variablesis an improvement on inferring coal permeability variations from well test data, which isaffected by multiple unknown variables at the same time.

Four separate experiments have been carried out. The first investigated the impact of higher burial pressures on permeability, a four-fold reduction in permeability was measured with confining pressure increase from 150-750psi. The second replicated the reduction in pore pressure during dewatering the intention was to measure ‘stress-dependent permeability’, a halving of permeability was observed with pore pressure reduction from 220-30psi. The final two experiments used methane gas to investigate the effect of coal shrinkage with changing pore pressure. Under constant stress conditionspermeability halved and under constant volume conditions permeability saw a significant fifteen-fold reduction.

Focus on the resulting magnitude of permeability change is more important at the current stage of this study than the absolute permeability change. The magnitude of permeability change can be used assensitivity in numerical simulation studies toassess the impact of pressure dependency of coal permeability and therefore better characterise coal reservoir behaviour and, consequently, improve the accuracy of any forecast derived from the reservoir model.
Revisiting EOR Projects in Indonesia through Integrated Study: EOR Screening, Predictive Model, and Optimisation
Authors: Hartono A. D. , Hakiki F. , Syihab Z. , Ambia F. , Yasutra A. , Sutopo S. , Efendi M. , Sitompul V. , Primasari I. , Apriandi R.
Published: October 2017

EOR preliminary analysis is pivotal to be performed at early stage of assessment in order to elucidate EOR feasibility. This study proposes an in-depth analysis toolkit for EOR preliminary evaluation. The toolkit incorporates EOR screening, predictive, economic, risk analysis and optimisation modules. The screening module introduces algorithms which assimilates statistical and engineering notions into consideration. The United States Department of Energy (U.S. DOE) predictive models were implemented in the predictive module. The economic module is available to assess project attractiveness, while Monte Carlo Simulation is applied to quantify risk and uncertainty of the evaluated project. Optimization scenario of EOR practice can be evaluated using the optimisation module, in which stochastic methods of Genetic Algorithms (GA), Particle Swarm Optimization (PSO) and Evolutionary Strategy (ES) were applied in the algorithms. The modules were combined into an integrated package of EOR preliminary assessment. Finally, we utilised the toolkit to evaluate several Indonesian oil fields for EOR evaluation (past projects) and feasibility (future projects). The attempt was able to update the previous consideration regarding EOR attractiveness and open new opportunity for EOR implementation in Indonesia.
Prediction and Analysis of PDC Bit Downhole Behavior Provides Insights and Efficiencies for Directional Drilling
Authors: Cuillier B. , Al-Enezi D. , Goswami B. , Al-Salamin M. , Al-Shelian J. , Sayed S. , Mikhail B. , Genidy E. El , Reboul S.
Published: October 2017

PDC bit designs for directional drilling typically sacrifice penetration rate for steering performance, resulting in a higher cost per foot. This paper discusses a process for modeling the drilling behavior of PDC bits, insights gained regarding bit efficiency when steering with various motorized and non-motorized rotary steerable systems (RSS), and field experience with the resulting bit design.

Prediction and analyses of PDC bit behavior used a bridgeable software platform to integrate various design applications. This allowed the combined analyses of performance objectives and criteria, including cutting structure, rock type, application, well profiles, drives, and 3D contact. Simulations were then run to examine the performance of different cutting structures relative to various drilling parameters, and matched to a specific drive system. An optimized PDC bit design was developed and manufactured, and its field performance was compared to the model and to PDC bit performance in offset wellbores.

The optimized design was manufactured in a 6 1/8-in PDC bit and run on motorized and non-motorized RSS. It resulted in significant ROP increases and a lower cost per foot compared to offset wells, while retaining a high level of steering response. In one well, the ROP was increased to 48.43 ft/hr versus a target of 35 ft/hr based on offset performance. The resulting cost per foot was reduced from $11.40 KD to $8.59 KD.

The paper examines bit performance and dull condition for the runs and compares them with offset runs. Field performance results validate the bit design modeling and simulation process, and emphasize the importance of integrating various performance analyses to improve bit efficiency without degrading critical steering characteristics.

Extensive development of cutting structures that "drilled on paper" combined with full scale bit laboratory testing has resulted in the development of a design process that combines multiple design objectives and criteria to model and simulate bit behavior during drilling. As shown by field results, this process of balancing the design provides the means to optimize overall performance and lower costs for many different bit applications.
Monitoring Imbibition of Water Into Shale Pore System: State of the Art
Authors: Al-Arfaj Mohammed , Al-Osail Mohamed , Sultan Abdullah
Published: October 2017

To understand the interactions between shale rocks and aqueous drilling fluids, the spontaneous imbibition of water phase into shale pore systemsneeds to be investigated. It is important to study the shale-fluid interactions to mitigate problems associated with drilling shale formations using water-based drilling fluids. Spontaneous imbibition experiments have been frequently conducted to assess the flowback and recovery for reservoir engineering applications. In this paper, the literature has been reviewed in an attempt to link the work that has been carried out in that area to study the water filtrate invasion of drilling fluids into shale rocks while drilling.

Over the years, different techniques and instruments have been used to study the spontaneous imbibition into shale rocks including: spontaneous imbibition device, which is basically analytical balance to measure the weight changes as imbibition progresses, pulse decay permeameter, scanning electron microscopy, X-ray tomography and nuclear magnetic resonance. To aid in analyzing and interpreting the results, the rocks are characterized in terms of: surface area, porosity, permeability and wettability. Fluids that have been used as the imbibing medium included: water, oil, brines, and surfactants.

Three imbibition mechanisms have been revealed by literature: capillarity, osmotic diffusion, and water adsorption. These mechanisms can be distinguished when imbibed water volume is plotted against time where the imbibition rate differs for three distinct regions. Factors that were found to have impact on imbibition process include: capillary pressure, porosity, pore size distribution, pore connectivity, effective permeability, presence of fractures, bedding, mineral composition and clay content, fluid type, and properties and depositional environment (marine or continental).