bluuebunny/crossref_metadata_2025 huggingface dataset:
How To Find Low-resistivity Pay In A Mature Oil Field - K Field Case Study
Authors: Poerboyo Savitri Mutiah , Suharya Kelik Rudi
Published: May 2016

Prior to 2010, all oil from the K field was produced from the Lower Sihapas Formation, where oil could easily be identified from electrical logs in these thick, high-quality sands. Then, in 2010, something unusual happened. When drilling an infill well, we noticed good oil indications from mud logs in sands above the Lower Sihapas Formation, despite the low resistivity less than 4 ohm-m. We completed the sand and it flowed 146 BOPD with zero water. This unexpected result prompted us to conduct a short two-week study to identify other candidate wells. The study consisted of: collection of mud and wireline log data in all K wells; re-running petrophysical analysis using new a, m and n values for low resistivity sands; and ranking candidate wells based on sand quality, gas readings, oil shows, initial oil rate prediction, well cost and the chance of making money.

The study identified 17 candidate wells to re-complete in the Upper Sihapas. To date, we have worked over seven wells with an oil gain of 700 BOPD and estimated incremental oil recovery of 175 million stock tank barrels. One of the worked-over wells, the one with the lowest EMV, flowed water. This paper describes the study, the resultant workover campaign and lessons learned.

Introduction

The mature K oil field is located on the western side of Padang Island in the Malacca Straits PSC, Sumatra, Indonesia as seen in Figure 1. The field has produced oil for 23 years. Current production is around 1,800 BOPD and cumulative oil production is around 64 MMSTB.

Oil is produced from the Sihapas Formation, which consists of the Lower and Upper Sihapas as seen in Figure 2. These two sandstone reservoirs have different characteristics, and are separated by thick shale. Oil production has predominantly been from the Lower Sihapas sands, which are thicker, areally extensive and have higher permeability. Oil-bearing intervals in the Upper Sihapas are generally thin, shaly, lenticular and discontinuous, with lower permeability.

This Upper Sihapas study was initiated to assess oil production potential in existing wells. This study was timely, given the oil rate decline and water cut increase in Lower Sihapas sands.

Geological Aspects of the Upper Sihapas

The Upper Sihapas formation is a massive (200–300 ft thick) body of non-calcareous, silty shale with numerous fine-grain sandstone streaks and inter-bedded sand lenses as seen in Figure 3.

Sediments within the Upper Sihapas formation were deposited in a shallow marine environment. This led to a formation water salinity of about 16000 ppm, much higher than the salinity of the Lower Sihapas formation of about 2500 ppm where the depositional environment was mainly deltaic.

The sands are mostly discontinuous, low resistivity with thicknesses less than 10 feet; though some thicker sands (10 - 15 feet) can be correlated across several K wells.
Advanced Reservoir Characterization for CO2 Storage
Authors: Al-Menhali Ali , Reynolds Catriona , Lai Peter , Niu Ben , Nicholls Norman , Crawshaw John Peter , Krevor Sam
Published: May 2016

Injection of CO2 into the subsurface is of interest for CO2 storage and enhanced oil recovery (EOR). There are, however, major unresolved questions around the multiphase flow physics and reactive processes that will take place after CO2 is injected, particularly in carbonate rock reservoirs. For example, the wetting properties of CO2-brine-rock systems will impact the efficiency of EOR operations and CO2 storage but reported contact angles range widely from strongly water-wet to intermediate wet. Similar uncertainties exist for properties including the relative permeability and the impact of chemical reaction on flow. In this presentation we present initial results from laboratory studies investigating the physics of multiphase flow and reactive transport for CO2-brine systems. We use traditional and novel core flooding techniques and x-ray imaging to resolve uncertainties around the CO2-brine contact angle, relative permeability, residual trapping, and feedbacks between chemical reaction and flow in carbonate rocks.

Introduction

Uncertainty around CO2 storage and EOR may be significantly reduced from a greater understanding of the fundamental physics of fluid flow and reactive transport that control rock-brine-CO2 interaction in the subsurface. The combination of unique multiphase flow properties and significant reactivity in the CO2-brine-carbonate rock system has major impacts on the injection, flow and immobilization of CO2 in the subsurface. These unique properties must be accurately characterized to reduce major uncertainties for CO2 storage and EOR in carbonate rocks. Observations of reservoir condition multiphase flow and reactive transport properties for the CO2-brine-carbonate rock system are provided including wetting properties, capillary pressure, relative permeability and residual trapping. A methodology is presented for utilizing a combination of novel and traditional core-flooding and imaging techniques for a comprehensive characterization of carbonate reservoir rock.
Uncertainty of Porosity Measurement Correlations using NMR and Conventional Logging in Carbonate Reservoirs
Authors: Al-Kharaa Hamad S. , Al-Amri Meshal A. , Naser M. , Okasha T.  M.
Published: May 2016

Porosity is a dimensionless parameter, defined as the ratio of pore volume filled with fluid to the bulk volume. Porosity is a critical volumetric parameter used to estimate the reserve for a given reservoir and it can be used as an input for reservoir simulation as well. In addition, porosity can be classified into two types, effective porosity (interconnected pores) and total porosity (connected and isolated pores). Total porosity is defined as the sum of effective porosity and clay bound water (CBW). In other words, total porosity obtained from conventional logging tools will be equal to effective porosity in the absence of clay and while it is not the case when clay is present.

There are several methods used to estimate porosity of the formation. These include: measuring actual porosity in the core laboratory, computerized tomography (CT) scan, neutron-density logging, sonic tools, and NMR logging tools. All conventional logging tools (neutron-density and sonic logging tools) are strongly dependent on lithology, whereas NMR logging tool is independent of lithology.

The NMR logging the most accurate compared to all other methods since it is independent of the reservoir lithology. It can be used to estimate the reservoir porosity directly without the knowledge of matrix lithology. On the other hand, conventional logging such as neutron-density and acoustic depend strongly on lithology which might yield incorrect porosity measurement. Several studies have been conducted to estimate porosity for both sandstone and carbonate reservoirs using different logging tools, however, determining porosity is a challenge in complex and unconventional lithologies. In sandstone, the presence of shale and clay minerals will affect the response of all porosity tools. Carbonate is even more complicated than sandstone due to its heterogeneity and triple porosity system (pores, vugs, and fractures). In addition, the assessment of porosity measurements accuracy using NMR logging will be considered in this study. An attempt will be made to develop an empirical correlation from NMR data to obtain reliable porosity estimation.
Thinly Bedded Reservoir Characterization, From Qualitative to Quantitative Approach, Case Studies in a Cenozoic Basin of Malaysia
Authors: Nurhono Achmad A. , Kantaatmadja Budi P. , Sing Thu Goh , Masoudi Rahim , Othman Mohamad B. , Rahman Nasir B A
Published: May 2016

The limit of resolution of seismic data is a complex issue that involves not only wavelet frequency, phase characters, data quality (S/N), interference, tuning, but also criteria on how to measure resolvability, which can hamper confident lithology, porosity and fluid prediction of thinly bedded reservoirs.

Widess's classic paper (1973) concluded that for thin beds (below ?/8 wavelength), the seismic character, peak/trough time and frequency do not change appreciably with thickness, and also amplitude varies almost linearly with thickness, which goes to zero at zero thickness. Thus, ?/8 of wavelength is considered to be the fundamental limit of vertical seismic resolution which depends on velocity and mainly frequency. Tirado's work (2004) revised Widess's model, which is not applicable to the real reflection, and concluded that as the bed thickness decreases, there is a gradual increase in the peak frequency, but below a certain thickness (at some fraction of tuning thickness), the peak frequency rolls off and return to the peak frequency of the wavelet at zero thickness. Thus, the key factor in determining seismic resolution is by enhancing the frequency spectral bandwidth which, nowadays, can be effectively achieved either by acquiring Broadband Acquisition or conducting Broadband Seismic Re-Processing.

We demonstrated various case studies on thinly bedded reservoirs using qualitative and qualitative techniques in a Cenozoic basin in Malaysia. The qualitative techniques involve the -90° Phase wavelets with Relative Colored Inversion, Spectral Decomposition, and ThinMAN broadband spectral inversion. The quantitative approach includes an integrated multi-disciplinary technique combining with Cascading AVO Simultaneous inversion and Stochastic Inversion calibrated with conventional and SHARP-OBMI logs, which together, significantly enhance imaging of the thinly bedded reservoirs. This unique integrated workflow has been applied in the field study, resulting in an increase of about 30% of hydrocarbon in-place volume, and has been successfully validated with available production/well data as well as newly drilled wells.
A new mapping method to assess aquifers vulnerability based on hydrogeological and seismic data - Case Study: Mio-Pliocene Aquifer in Hassi Messaoud - Algeria
Authors: Bensenane Fadia K. , Dhina Okba
Published: May 2016

Non renewable groundwater resources in some arid regions are the unique source of water and constitute strategic reserves for more than ever with the expected water shortage in the near future. Thus, contamination due to the infiltration of pollutants coming from oil and gas industries is one of the major risks that are jeopardizing these valuable resources.

The main purpose of this paper is to present the widespread aquifers vulnerability evaluation methods prior to introduce and discuss the new mapping method we propose for oil and gas upstream activities.

The rationale for this mapping method is linked to time of travel and the quantity of contaminants that move from the surface to the aquifer. Three key parameters are considered:Consolidation of the upper geologic layers in the unsaturated zone (C);Depth to water table (D);Aquifer Media (A).

On one hand, seismic data have been used to estimate the consolidation of the unsaturated (vadose) zone. On the other hand, hydrogeological data from almost a hundred water wells in Hassi Messaoud field in Algeria have been used to determine the hydraulic head, the static level and the local underground flow of the mio-pliocene water table.

Therefore, processed data were used for the purpose of drawing the vulnerability maps allowing a better understanding and assessment of the aquifer sensitivity to potential pollution.

This simple yet useful method is developed to be used as a decision making tool when dealing with groundwater protection in oil and gas activities.
Permeability Multiplier Prediction using 3D OBC Seismic Data
Authors: Matarid T. M. , Ibrahim K. , Ibrahem M. S.
Published: May 2016

This work describes an approach in characterizing fractured reservoir of upper Jurassic Carbonate using seismic azimuthal anisotropy. The ultimate objective of this study was to attempt to map permeability multiplier inter-well for the contribution to the simulation model and the subsequent development plan of an oil field offshore Abu Dhabi.

The azimuthal seismic anisotropy for fracture prediction method showed fractures that are similar to those indicated by well methods and therefore seismic can be used to detect natural fractures between wells. The confidence in the seismic fracture prediction method's ability to capture information about fracture in Carbonate reservoir has increased if the well data are accurately integrated.

The study interval exists in the dense zone of the Upper Jurassic reservoir with total thickness of 120'. The fractures evidence have been compiled from well data, such as Core, FMI, orthogonal shear sonic, production test, multi-arm caliber….etc. Present day stress is captured from induced fractures direction, borehole breakout, offset field stress map, Eocene structure map and world stress map. All compiled information's indicated maximum horizontal stress of N10°-30°E direction.

The four sectored wide azimuth seismic data set have been fitted to an ellipse to find out the fast and slow velocity direction and the difference between those velocities. The Interval Velocity is sensitive to Lithology, porosity, pore fill; the Vint-Slow is sensitive to the minimum horizontal stress. The lower the VINTslow, the less the minimum horizontal stress, which allows the fracture apertures to be more open.

It is observed that the seismic anisotropy map for fractures showed a dominated direction (NNE-SSW) that match with present day stress field. The azimuthal Vint records current day stress field, not paleo-stress field. Good correlation between well permeability multiplier and the fractures map, particularly at the two reference wells.

Following the analysis of the azimuthal seismic anisotropy maps such as azimuthal amplitude and interval velocity, a good correlation has been observed between the seismic anisotropy components and the production well test. The two seismic anisotropy components that showed a great deal of link with the computed well permeability multiplier are the computed slow interval velocity and the anisotropy azimuth deviation from the known present day stress.

Therefore, the following equation has been written to invert those azimuthal seismic components into permeability multiplier. The resulted map showed match at both input wells and one blind well.
Empowering Women in the Workforce: Leadership Roles
Authors: Yousuf Muna
Published: May 2016

Global general perception of leadership roles

Worldwide leadership roles are traditionally held by men. While the share of women in the workforce is increasing, it remains difficult for them to reach senior positions, which are mostly held by men. The Qatar National Development Strategy 2011–2016 seeks to increase the number of women in leadership roles by 30 per cent.

Perceptions in the GCC that have traditionally limited career advancements for women

A number of cultural, organisational and personal challenges hamper women from reaching senior positions. Women are perceived to work responsibilities. In addition, traditional views on what constitutes appropriate spheres for women's employment influence education choices for education and promote occupational discrimination.

How to promote women to leadership positions

Research and evidence indicate that the appointment of women as top managers can positively improve the performance of a company. Global corporations, conscious of the value of gender balance at all levels, are more eager to hire and promote women. Developing professional women's skills in decision-making and leadership help them realise their full potential. Examples of development opportunities include providing training, instituting career development initiatives and mentoring programs, and ensuring networking opportunities.

Sustaining continuous growth for women in leadership roles

Today, some professional women in Qatar are already in challenging leadership roles. We need to ensure that we sustain these current positions while encouraging continuous growth. [Actual paper will review statistics and demographics for GCC, and in particular State of Qatar, and how they align with the Qatar National Vision 2030 for Qatarization].
Barzan Gas Project: Clean Source of Energy Supporting Qatar
Authors: Bacon William (Bill) , Al-Kuwari Essa  Matar M. R.
Published: May 2016

RasGas Company Limited (RasGas), on behalf of Qatar Petroleum and ExxonMobil Barzan Limited, is in the execution phase of the Barzan Gas Project, constructing two of the largest natural gas processing trains in the world to provide the State of Qatar with natural gas and associated liquids to fuel its growing economy. At peak, more than 30,000 people from over 40 nations will work together to execute this project in a safe and environmentally responsible manner.

Natural gas -associated gas field, will be produced at a rate of 1,900 million standard cubic feet per day (mmscfd) by Barzan Gas Project offshore facilities, comprising three unmanned wellhead platforms, two subsea pipelines, and two onshore gas processing trains, all of which will be operated by RasGas Company Limited on behalf of Barzan Gas Company Limited. In addition to producing natural gas, ethane and field condensate for the domestic market, Barzan Gas Company Limited will export liquefied petroleum gas (LPG), sulphur, and plant condensate to the international market.

Against the backgrorapid rise to prominence on the world stage, broad development of its economy, industry, commercial and social systems, and the hosting of high profile international events, including the 2022 World Cup, ambitious and impressive expansion programmes are being undertaken, including a new airport, new seaport, metro and rail networks, doubling the number of hotel rooms, new schools, universities, hospitals, sports stadiums, conference and exhibition centres. Natural gas supplied from the completed Barzan facilities, a landmark development, will play a key role in supporting n and reliable source of energy from world class production facilities, and in doing so, support the four pillars of the Qatar National Vision 2030: human development, social development, economic development, and environmental development.

The Barzan Gas Project takes its name from a fortified tower built in the early 20th century located north of

Introduction

The State of Qatarexceptional economic progress is evident in the increasing standard of living of its people, sustained by major advances in economic, human and social development. From modest beginnings, Qatar is undergoing a transformation to become dynamic and vibrant economies, setting an outstanding example of how wise leadership and prudent development of its diverse rich hydrocarbon resources can successfully lead a nation on a pathway to long-term prosperity, building a dynamic 21st century economy, while maintaining its cultural and traditional values as an Arab and Islamic nation that places the family as the central pillar of society.
Development of an Online, Non-Intrusive Means for Detecting Onset of Formation Water Production in Gas Flow Lines
Authors: Mohammed Sabry A. , Aggour M. , Fraim M. , Aboegila A. , Farooqui M. , Al-Kharaz H. , Ashkanani M. , Marmoush M.
Published: May 2016

Production of high salinity formation water with gas presents major operational and reservoir management challenges in gas reservoirs. Early detection of unexpected water production is critical for ensuring prompt action to prevent accelerated corrosion damage in surface pipelines and facilities if they are not designed to handle the produced brine. Several methods exist for detecting water in pipelines which are based on electrical, electromagnetic, and acoustic measurements. While most of the existing methods are intrusive requiring direct contact between the measurement probe and the flow stream, all such methods suffer from low accuracy of measurements and dependence on water composition and salinity.

This paper reviews the various technologies that are in use to detect and measure water production. It also describes the theoretical background and the laboratory testing of a new means for detecting presence of formation water in gas flow lines.1–10 This work is part of a joint collaboration between RasGas Company Limited and Texas A&M University at Qatar (TAMUQ) aimed at developing a device which is: non-intrusive, clamp-on externally on the flow-line, accurate, and independent of saline water composition. This technology is based on neutron elastic-scattering and activation interactions. The laboratory testing is performed using simulated field conditions to determine the feasibility and accuracy of the measurement technique. Based on the laboratory results, a prototype device is planned to be constructed for field testing. Safety aspects of the process application both in the lab and in the field have been thoroughly examined and comprehensive safety measures have been developed and implemented per the health and safety regulatory requirements.

The paper also presents the findings from a simulation study using the Monte Carlo N-Particle (MCNP5) neutron flux simulator11 to examine the feasibility of the proposed method and to properly design and optimize the experimental setup and procedure.

Introduction

Produced fluid in gas fields consists, generally, of gas, condensate, and condensed (zero salinity) water. As production progresses, formation saline water (brine) can be produced with the condensed water. This can affect the operation and safety of the production system by accelerating corrosion and scaling potential, especially in the presence of acidic gases such as CO2 and H2S and the inorganic salts dissolved in the brine. Brine can also lead to emulsion and bacteria related problems. Therefore, it is very important to detect the presence of formation brine in the system as soon as it starts to be produced.
Magnetic and Gravity Data Acquisition in Deepwater: a new Frontier for the Potential Field Geophysics
Authors: Gabbriellini Gianluca , Spadini Giacomo , De Marchi Eliana , Filippini Michele , Finotello Roberto , Indrigo Dennis
Published: May 2016

The O&G industry is moving offshore into increasingly deep waters in order to explore for, develop and exploit hydrocarbon reservoirs in new frontier areas. Standard gravity and magneto-gradiometric acquisitions in such areas are usually performed with ship-borne and airborne techniques. This implies that, especially in ultra-deep waters, the measuring sensors are very far from the geological causative bodies, thus leading to a poor SNR.

Eni E&P is committed to adopting and deploying novel proprietary approaches and tools in these challenging environments. As part of an ultra-deep water E&P initiative, Eni and Tecnomare have designed, developed and tested the "AUVG", a new Autonomous Underwater Vehicle capable of carrying gravimetric and magnetometric instruments onboard for the acquisition of potential field data close to the sea bottom in ultra-deep water environments. The vehicle, which is carried by a supply vessel and launched from it near the area of interest, is autonomously capable of navigating underwater for up to 20 hours, reaching the sea bottom and starting the data acquisition, performing pre-programmed trajectories, avoiding unexpected obstacles, storing the entire data set and emerging in a predetermined position. The vehicle can be located using a radio, strobe lights and a satellite localizer. By means of a Wi-Fi data connection, it is also possible to download data and re-program a new geophysical survey.

Gravimetric and magnetometric data acquired by means of an AUV in deep water are characterized by a much higher SNR as well as a higher spatial resolution. These improvements have been experimentally highlighted by a recent test carried out in deep waters in the Ionian Sea.

INTRODUCTION

The measurement of gravity and magnetic field data, also generally named potential field data, is extensively used in exploration geophysics. The common goal of potential field methods is to improve the definition of subsurface geology. Gravity field data provide information about anomalous density within the Earth. The interpretation of the gravity anomaly and/or related quantities (such as its gradient) is useful to understand where the density contrasts are located. It is particularly useful in saline contexts, where the salt bottom is not always visible in seismic data. Magnetic field data are useful to highlight magnetization contrasts caused by basement uplifts and subsequently to identify oil and gas traps, if necessary.

Although it is not possible to determine a single source for an observed potential field anomaly, their interpretation can be useful in obtaining a geological screening of the area; they can provide constraints in the seismic interpretation phase and can also be used as input data for joint inversion applications. It should be noted that, compared to the seismic acquisition, the potential field acquisition is considerably less expensive.
Syngas Technologies
Authors: Al-Mulla Jassem
Published: May 2016

This paper will discuss the comparison between the three leading Syngas manufacturing technologies; Partial Oxidation (POX), Autothermal Reforming (ATR) and the Steam Methane Reformer (SMR) technology. Also, this paper will discuss the development of the Catalytic Partial Oxidation COPox syngas technology. The discussion will focus on illustrating the general syngas chemistry of each technology and where the COPox process fits into the spectrum of syngas technologies. It will also discuss the application of the first two technologies in commercial plants and some of the critical operating parameters that can influence the performance and the efficiency of syngas production such as, feed gas composition, operating temperate and pressure.

Syngas can use in the Fischer-Tropsch and methanol process, as fuel, or as an intermediate for chemical production. Syngas treatment and removal of sulfur, NH3, soot and HCN containing compounds is essential to the final application of the gas. This paper wills discuss the effect of the impurities in the syngas.
"What Happened To All My Gas?" P/z Plots In Layered Reservoirs
Authors: Ross Fraser
Published: May 2016

P/z plots for low permeability or layered reservoirs do not yield a straight line which extrapolates to the IGIP; they are curved and deviate strongly from the theoretical straight line. Consequently, the interpretation of the P/z plot is often grossly misleading and typically significantly underestimates the IGIP, leading to erroneous production forecasts and reserve estimates. The problem with the simple P/z material balance plot is that the pressure measured using a pressure build up test is not representative of the drainage volume of the well. When P/z plots cannot be analysed quantitatively, typically a numerical reservoir simulator is used to match the shut-in bottom-hole pressures and the continuously measured wellhead rates and pressures. However, a simple multi tank material balance method can provide valuable insights into the reservoir behavior and can be used either as a precursor to, or to replace numerical simulation. This paper describes a technique that can be used for medium to high permeability reservoirs.

Introduction

This paper discusses the problems associated with applying the simple P/z technique to layered reservoirs; plotting the downhole static pressure vs cum production will always give the wrong value of the IGIP. This paper presents how pressure transient data and PLT data can be combined with a simple multi tank model, which can be programmed in a spreadsheet, to provide a good understanding of the impact that reservoir layering has on the pressure behavior of the reservoir.

In order to provide pressure data for this analysis, a 2 layer, dry gas reservoir model was constructed using a reservoir simulator. The details of this model are shown in Appendix 2. Because a model was used to generate the data used in the interpretation, the model inputs of IGIP, kH, re, skin and non-Darcy coefficient are known so the results of the interpretation can be compared to the model inputs. In other words, are the calculated layer volumes consistent with the input values?

The pressures used for this presentation were obtained by shutting in the well (in the simulator) every year for a simulated 4 day pressure build up. The pressure transient data for the first pressure build-up were plotted using the conventional log-log plot and is shown on Figure 1.
Application of an Integrated Approach to Preserve Geologic and Seismic Consistency in a History Matching Workflow of a North Sea Chalk Reservoir
Authors: Sudan Hari , Tolstukhin Evgeny , Hu Lin
Published: May 2016

Reservoir surveillance using 4D seismic has become a valuable resource for managing decisions under uncertainty. This paper highlights an integrated workflow to preserve geological consistency while calibrating a reservoir model using 4D seismic and production data. We demonstrate a successful application of this approach on our North Sea chalk reservoir undergoing waterflood, where a number of repeat seismic surveys have been acquired over time and leveraged as a quantitative source of information for describing the spatial distribution of reservoir properties and compaction. This seismic monitoring data has resulted in the ability to better manage the waterflood by providing fluid movement insights and subsequent improvement of infill well placement. To capture geologic variability and ensure model predictability, geostatistical parameterization techniques using multiple-point statistics are used to represent the uncertainty in the reservoir model. Additionally, the workflow employs a rock physics model to generate a synthetic 4D seismic response from flow simulation. Inconsistencies between the predicted and observed 4D differences are used to classify the reservoir model shortcomings. The uncertain geological parameters are updated in an optimization loop through the minimization of a misfit function comprised of both production and 4D seismic misfit formulations. The closed-loop workflow is managed by an in-house computer-assisted history matching tool using a stochastic optimization algorithm. The integrated approach yields improved reservoir management by encouraging multi-disciplinary collaboration between geological, geomechanical, geophysical and reservoir engineering disciplines.

Introduction

The use of 4D seismic has proven to be a valuable resource for managing decisions under uncertainty. The task of reservoir history matching is generally an ill-posed problem because there exist as a number of potential parameter combinations that generate similar simulated reservoir pressure and production responses. The fundamental reason this occurs is history matching spatially distributes uncertain geological or dynamic parameters (e.g. porosity, permeability, etc.) using localized well information from production data. The geological parameters in between the wells remain largely uncertain or unknown. To reduce inter-well uncertainty, the spatially more dense 4D seismic data can be used to mitigate the non-uniqueness by reducing the number of acceptable models.

A fully integrated workflow has been developed to ensure the predictability in our model forecasts by preserving the geologic and seismic consistency. This workflow dynamically couples all elements of the seismic to simulation workflow by using a computer-assisted history matching procedure.
A Comprehensive Approach of Well Integrity Surveillance
Authors: Al Khamis Mohammed N , Al Khalewi Faisal T , Al Hanabi Mohammed , Al Yateem Karam , Al Qatari Ayman , Al Muailu Husain
Published: May 2016

The well integrity surveillance program is a mechanism applied to oil, gas and water production/injection wells to ensure the sound quality and healthiness of all their completion components. Currently, there are differences in the well integrity surveillance programs applied by field operators worldwide due to the differences in the causes of well integrity issues that are faced in every field or geographical location. Recognizing such differences, Saudi Aramco formed a Well Integrity Surveillance Guidelines and Best Practices (WISG&BP) team to review and establish a comprehensive well integrity surveillance program that can be applied corporate wide for all well types (oil, water and gas).

The developed program not only ensures the identification of well problems at its infancy but also maintains the healthiness and upkeep of Saudi Aramco asset. This surveillance program focuses on the following six primary well integrity surveys: Wellhead valves integrity inspection and greasing.Surface and Subsurface Safety Valves (SSV & SSSV) and Emergency Shut-Down (ESD) System functionality and integrity testing.Annuli survey.Landing base inspection.Temperature survey.Corrosion logging.

An application has been developed to streamline and automate the planning, scheduling, execution, data validation and data posting process to ensure compliance with these best practices. This application provides tracking capability of the surveillance program and initiates alert, notification and escalation to the responsible entity at every stage of the surveillance process. The wells with identified integrity issues are flagged on a Well Watch List and closely monitored until their issue is resolved. This surveillance program is reviewed and updated every 2 years to reflect the advancements in surveillance technologies and capture any necessary modifications based on arising field observations.

This paper summarizes the well integrity surveillance program applied in Saudi Aramco. It provides a workflow of the well surveillance process and describes the automation application used to capture and track the program implementation. The comprehensive strategy provided in this paper can be used as guidelines for maintaining the well integrity of all well types worldwide.
Treatment of Produced Water from Unconventional Resources by Membrane Distillation
Authors: Minier-Matar J. , Hussain A. , Janson A. , Adham S.
Published: May 2016

Unconventional resources (Shale gas/oil) use significant volumes of water for hydraulic fracturing (fracking). While some of the water used is fresh groundwater, there are more environmental pressures to use brackish water sources for fracking. This brackish water may need to be treated to lower the saturation levels and to allow mixing of field chemicals. Unconventional resources also produced high volume of flow-back water (produced water). This produced water (PW) contains high levels of total dissolved solids (TDS) and desalination may be needed to allow recycling or reuse of this water source.

Membrane Distillation (MD) is an innovative process that can desalinate highly saline waters (30,000–100,000 mg/L TDS) more effectively than reverse osmosis. As a proof of concept, bench-scale MD testing were performed on brackish and produced water samples (30,000 mg/L-60,000 mg/L TDS) obtained from Texas. Results have shown excellent TDS rejection (99.9 %) on all the water samples that were tested without impacting membrane's flux performance.

To evaluate the O&M and scale up issues, two one m3/day MD pilot units are currently operating side by side at a local desalination plant in Doha. Brine from the thermal desalination plant was used as representative high salinity water (70,000 mg/L), similar salinity levels could be found in brackish groundwater and/or flow-back water. It was assumed that all other contaminants that could cause membrane fouling (such as suspended oil, solids, organics, microorganisms) will be removed in a pretreatment step prior to MD.

Preliminary results showed that the pilot units were successful in completely removing salt. Flux was very stable for more than 2 weeks. However, it was concluded that pretreatment is critical for stable performance of the MD units. This presentation will provide up to date data on MD bench and pilot-scale performance with O&M issues and projected cost estimates.
Assessing Reservoir Fracture Potential over Kra Al-Maru, Riksah Structure in the Kuwait Gotnia Sub-basin
Authors: Srigiriraju Ramachandra , Heyam Heyam , Al Adwani Talal Fahad , Banik Nikhil , Chakrabarti Bhaskar , Ghneej Ali Abu , Alaa Moustafa , Amer Aimen , Jaradat Awni
Published: May 2016

We present an exploratory case study of the oil and gas field located onshore within the Gotnia sub-basin located in northwestern Kuwait (Fig-1). Main objectives of this study include: to delineate the Kra Al-Maru and Riksah structure, to establish fault network, to assess fractured reservoir in its entirety, to achieve optimal depth conversion, to identify and assess critical inputs for fracture modeling and to provide key inputs for geo-modeling, all which lead to describing the location.

Structurally, the area is characterized by four main fault systems. Most of them have subtle seismic signatures on vertical sections as observed on poststack 3D seismic data. The dominant trends in the region are oriented NS and NNE-SSW where the unique. Kra Al- Maru structure is oriented NW-SE, which delimits the main structural high; however, dominant structural trends observed in sets of wells show NS, NNE-SSW trends. The second fracture set observed in the wells is oriented NE-SW, marked by minor vertical throws. The third and fourth fracture sets are oriented WNW-ESE, NW-SE characterized by no fault throws. Observations from core studies also support results achieved in this study.

Riksah structure is a well-defined four-way-closure anticline and appears to be a reasonable areal entrapment of about 33 km2. Its prospectivity is dictated by fracture potential of the reservoir. It is separated by a saddle like feature from Kra Al-Maru structure located to the west of this culmination.

The study indicates that the actual orientation of the structure, has most likely undergone fault block reorientation, fault reactivation and relative movement and accentuated folding due to compression effect. The increased stress on the flanks of the structure and the local tectonics are responsible for rotation of structure, which contributed to the evolution of the Kra Al-Maru structure and the orthogonally oriented Riksah structure as indicated by our study. The structural analysis indicates that all major open fractures align NNE-SSW.

The Riksah structure is a well defined four-way-closure anticline; however, the prospectivity is dictated by fracture potential of the reservoir. The evaluation of the fracture potential of the reservoir is best served by the azimuthally (AVOAz) processed 3D seismic data integrated with well observations. However, in the absence of AVOAz data, the study is supported by integration of well observations and key seismic attributes. The seismic attributes are, edge detection/enhanced seismic attributes, combined with prestack seismic inversion attributes like the Poisson's ratio which is governed by established relationships at wells.
Pushing Maximum Reservoir Contact Applications to New Limits in Tight Facies: A Case Study of Middle East's Highest Reservoir Exposure Producer
Authors: Suwailem M. A. , Zarea M. A. , Saleh R. F. , Verma C. X. , Nooruddin H. A.
Published: May 2016

The paper presents the evolution of reservoir management strategies that supported a recently drilled penta-lateral producer, which set a company record of total reservoir contact in a major greenfield in the Middle East. This paper will investigate the maximum reservoir contact (MRC) evolution in the field, the design phase of this game-changing producer, lessons learned and future implications.

The reservoir management objective for this producer was to capture oil reserves in tight layers (less than 10 md) in a gas cap driven carbonate reservoir while delaying gas breakthrough. This design was employed to push the MRC application to new limits of more than 16 kilometers to deliver more production at reduced well requirements while honoring best-in-class reservoir management practices.

In the design phase, a very high resolution reservoir simulation model was used to model the performance of this producer. Several sensitivity cases were conducted testing various well designs in terms of lateral spacing and completion depths. Subsequently, this producer was drilled with smallest lateral spacing (62 meter) closer to the oil-water contact (OWC).

The drilling of five laterals in 6 1/8" slimhole was a challenging task that posed hole cleaning threats across the horizontal sections and risked tight hole turning to stuck pipe. Through careful planning and team collaboration between various departments, the well was completed successfully with minor problems. In addition, the well was completed with two permanent downhole monitoring system (PDHMS) gauges and inflow control valves (ICVs) to manage water/gas movement and to ensure lateral clean-up.

Introduction

Field Background:

The greenfield is located in the South Eastpart of the Arabian Penensuila and is primarily producing from one carbonate reservoir. The oil column in this reservoir is overlaid by a huge gas cap and is underlain by a weak aquifer. Gravity drainage mechanism with gas cap expansion is the main drive mechanism (Saleri et al. 2003).
Vertical and horizontal pressure depletion trends captured by AVA Geostatistical Inversion conditioned reservoir modeling: An example from Late Messinian lacustrine turbidities reservoirs, Nile Delta, Egypt.
Authors: Vaughan R.  D. , Ali M. , Mustafa A. , Adly T. , Sulistiono D. , Petrov A.
Published: May 2016

AVO and seismic inversion has been successfully applied during the exploration phase of the Late Messinian Abu Madi Formation in the central Nile Delta of Egypt. Several gas condensate discoveries were made using this technique as a Direct Hydrocarbon Indicator (DHI) and risk mitigation tool. Deterministic inversion was further employed to delineate the overall lateral extent of the field and gross reservoir character during the appraisal phase of one particular field. A comprehensive well data acquisition programme for several wells revealed a complex lateral and vertical reservoir stacking patterns with highly heterogeneous reservoir parameters. The reservoir sequence is attributed to lacustrine turbidities deposited in semi-isolated Late Messinian Basins. Informally, the Abu Madi Formation can be subdivided in to upper and lower members. Intraformational shale barriers and baffles are commonplace. The stacked reservoir sands cannot be visualised and differentiated by the existing deterministic inversion products but each sand package displays complex vertical and lateral pressure trends.

This paper describes an AVA Geostatistical Inversion process integrated with rock physics modelling (using differential effective medium theorem) of the wells to generate high resolution multiple rock property models with the aim of capturing reservoir heterogeneity and the observed pressure trends. The probabilistic representations of lithology, water saturation, permeability and effective porosity captured the range of uncertainty remaining after appraisal drilling to provide equi-plausible models to further de-risk future development of the field. Flow simulation modelling is used to monitor and predict pressure depletion trends to optimise further infill drilling and effectively manage the reservoir.

Introduction

The Late Messinian Abu Madi Formation is a prolific producing reservoir in the Nile Delta of Egypt. The first discoveries were made from the late 1960's onwards focused along the Abu Madi Valley trend (Rizk, 2002). A number of fields were subsequently discovered within this north-south trending incised valley trend. More recently exploration focused to the west of the Abu Madi Valley trend in the central Nile Delta area. Despite near-continuous exploration from the mid-1960's the area yielded no commercial discoveries. Following a phase of extensive 3D seismic acquisition and interpretation several fields were discovered from 2007 onwards. Most discoveries have made on structurally robust traps which usually comprises some stratigraphic trapping elements (facies changes and sand pinch-out). All discoveries were supported by positive AVO responses which generally conform to the mapped structural traps.
Detecting Leaks in Abandoned Gas Wells with Fibre-Optic Distributed Acoustic Sensing
Authors: Boone K. , Ridge A. , Crickmore R. , Onen D.
Published: May 2016

Before any well is completely abandoned, some jurisdictions have governmental regulations which must be met and carried out by all companies. The main objective of these regulations is to prevent the production of oil and/or gas in the well by isolating and covering all porous zones. Monitoring with fibre-optic distributed acoustic sensing (DAS) systems allows for leak detection within the well bore and mapping migration through the cement with full-wellbore coverage. DAS provides a cost-effective method to accurately determine the depth of a leak or multiple leaks and profile gas movement due to casing failure, failure in wellhead seals, etc. In vertical wells or wells with low deviation, the optical fibre can be easily deployed by attaching a weight bar to the end of a steel tube containing fibre and running it to depth as a temporary installation or left in place as a permanent monitoring capability. Alternatively, a fibre that is already permanently installed behind the casing and cemented in place can also be used. Acoustic events from the gas movement produce a very small strain in the fibre. The strain can be measured at surface and depth-matched using the speed of light in the fibre. After characterizing the flow in the well under open and shut-in conditions, a decision can be made on how to address the leak. This paper will describe DAS technology and how it is deployed as well as show the analysis and results from a casing leak detection trial.

Introduction

DAS technology utilizes fibre optic cable as a distributed microphone, with high spatial resolution over long distances. In DAS, a short pulse of light is launched into the fibre, as a probe. During the manufacture of the fibre, imperfections created during the cooling of the fibre, cause variations in the refractive index of the glass. These imperfections are very numerous and randomly distributed, and are referred to as scattering sites. When the light probe advances down the fibre, a small portion of its light becomes scattered by the scattering sites. About 0.1%, of the scattered light gets captured by the fibre and is guided back towards the launch direction, and this backscattered light is detected by a detector within the DAS system.

Figure 1 shows the relationship between the launched light probe (in blue) and its backscattered response. At time t0, a light probe is launched into the fibre and the figure shows the interaction of the light probe with the fiber, causing backscatter, denoted by red arrows, at some arbitrary time, tn. At some later time tn+1, the backscattered response (in red) has propagated back towards the launch direction, and the light probe (in blue) has continued to propagate towards the end of the fibre. As the light probe propagates down the fibre, a continuous stream of backscattered is light is generated throughout the fibre. The light probe and backscatter detection process is referred to as interrogation.