bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving People’s Lives: For the Public Benefit
Authors: Meehan Nathan
Published: October 2016

President's column

What is the mission of the Society of Petroleum Engineers (SPE)? Why do we collect, disseminate, and exchange technical knowledge? There are plenty of reasons why such activities are valuable. Our mission statement gives a reason for this activity, namely, for the public benefit.

Mission statements of various professional societies often reflect the need to serve the public in some way. The American Society of Mechanical Engineers’ mission statement includes its purpose “to serve diverse, global communities” and “applying engineering knowledge for improving the quality of life.” The mission of the American Institute of Chemical Engineers is to “provide essential value to our members and partners, advance civil engineering, and serve the public good.” The mission of the National Academy of Engineering is “to advance the well-being of the nation.”

The mission of SPE is:

To collect, disseminate, and exchange technical knowledge concerning the exploration, development and production of oil and gas resources, and related technologies for the public benefit; and to provide opportunities for professionals to enhance their technical and professional competence.

The mission was adopted more than 50 years ago. The statement about providing opportunities for professionals to enhance their technical and professional competence forms the basis of many of the Society’s training and professional development activities. The phrase I have emphasized is occasionally replaced by ellipsis in SPE Powerpoint presentation and not discussed enough. Before we discuss SPE’s role for the public benefit, let us look at engineering’s role.

Engineers are uniquely responsible for the machines, buildings, energy, and technology that surround us and are fundamental to our lives. After the Unconventional Resources Technology Conference in San Antonio, Texas, this year, I revisited the Espada Aqueduct built in 1731, completed in 1745 by Franciscan missionaries to provide water for irrigation. It reminded me of the Roman aqueducts built as early as 300 BC and other feats of engineering that resulted in improved health, sanitation, and productivity in societies. The state of engineering at the time was craft work relying on working knowledge of construction, geometry, and fluid flow principles. This type of engineering dates back to the pyramids.

Modern engineering developed in parallel with the industrial revolution, powered by coal.
2015 SPE Annual Technical Conference and Exhibition: ATCE Looks to Brighter Future Amid Challenging Market
Authors: Boschee Pam , Jacobs Trent , Parshall Joel , Rassenfoss Stephen , Whitfield Stephen , Wilson Adam
Published: October 2016

Conference review - 2015 Annual Technical Conference and Exhibition

More than 13,500 oil and gas professionals gathered at SPE’s Annual Technical Conference and Exhibition (ATCE) on 28–30 September in Houston, making it the second highest-attended ATCE.

The conference, which focused on the positive potential of the future while addressing the current challenges of the oil and gas market, furthered the exchange of industry knowledge with more than 400 technical papers presented at 46 technical sessions. In addition, 450 companies filled the exhibition floor.

Opening Session

A look ahead on the global energy road map to 2040 prompted a lively discussion among panelists at the opening general session on the first day. No one underestimated the challenges faced by the oil industry in the current climate of low prices, project cutbacks, and layoffs. But the discussion also stressed the resilience of the industry, the continued importance of fossil fuel energy to the world economy, and reassurance that the industry will come through a difficult period and be stronger.

Bernard Looney, chief operating officer of production at BP, noted that even before the drop in oil prices, the company was increasingly aware that costs had “really gotten out of control in our industry, particularly in the last 5 years.” The oil price collapse compounded that challenge.

“Small things, they add up, all the way to very big developments like Mad Dog Stage 2 here in the Gulf of Mexico,” Looney said. Through re-examining the project, BP has lowered the price tag from USD 20 billion to USD 14 billion. “And, quite frankly, the question for the team today is could we do that project for less than USD 10 billion?” he said.

Looking forward, Looney cited the positive role that fossil fuel should have in lifting people from poverty around the globe. At the same time, Looney stressed the need for the world to put a price on carbon. Notwithstanding the challenges of the current economic environment, Looney said, “I’m convinced, and I think we’re convinced, that we’ll get through this. The industry has been here before, and we’re an incredibly adaptive industry.”

Innovation, Collaboration

Incoming 2016 SPE President Nathan Meehan, a senior executive adviser at Baker Hughes, noted that in the 1980s, oil prices were depressed and, during those rough times, many of the technologies that enabled production from unconventional and deepwater reservoirs were developed.

Speaking at the SPE Research and Development Technical Section dinner on the eve of the conference’s opening, Meehan called upon industry professionals to respond to the oil price downturn with a renewed spirit of determination. “You are the ones who will have to come up with the technologies that enable us to solve problems differently than we used to solve them,” he said. “You can do it in today’s price environment. You can come up with these innovations.”
Techbits: SPE Effluent Discharge Management Workshop Addresses Standards and Regulations
Authors: JPT staff _
Published: October 2016

Techbits

The SPE Trinidad and Tobago Section recently hosted an Applied Technology Workshop (ATW) on oil and gas effluent discharge management in Port of Spain, Trinidad and Tobago.

The event brought together petroleum and petrochemical industry professionals involved in generating effluent discharges to the receiving environment, regulators, and those involved in the design, construction, operation, and maintenance of treatment systems for effluent discharge.

The goals of the workshop were to

Explore regional and international legislation as applied to effluent discharge in the oil and gas industry and compare with the local regulatory framework in Trinidad and Tobago.

Define the compliance issues of water pollution rules in Trinidad and Tobago specific to the oil and gas industry.

Obtain the industry best practice for effluent treatment and disposal with emphasis on large oil and gas drilling and production operations both onshore and offshore.

Explore the available technology and its applicability to achieve compliance.

There was a consensus that urgent collaborative action is needed among all stakeholders. The path forward received endorsement from the country’s regulators (the Ministry of Energy and Energy Affairs [MEEA] and the Environmental Management Authority [EMA]), operators, and service providers. The areas of focus in the workshop included legislative reform, use of applicable technology, and availability of resources.

Legislative Reform

Participants discussed the Trinidad and Tobago legislation pertaining to effluent discharges. There were also presentations on experiences setting effluent discharge standards in the North Sea using the Convention for the Protection of the Marine Environment of the Northeast Atlantic or OSPAR Convention, for possible use as a framework.

The topics of discussion about legislative reform centered on the following:

Are our current water pollution rules relevant and appropriately framed in the current environment?

The consensus was that there is an opportunity for the review of the current Water Pollution Rules created in 2001 and amended in 2006. For example, there is the need for ambient water-quality standards coupled with discharge standards. Current discharge standards were deemed to be stringent by some presenters compared with other jurisdictions such as OSPAR. OSPAR is using a holistic or risk-based approach in regulating effluent by the use of mixing zones and impact-based ambient water-quality standards vs. technology-based discharge parameters. To develop new ambient water-quality standards, a baseline study must be conducted on the receiving environment of Trinidad and Tobago.
Technology Focus: Gas Production Technology (November 2015)
Authors: Wilson Scott J.
Published: October 2016

Technology Focus

Only 2 years ago, the conventional wisdom was that oily or liquids-rich plays were the only place to put capital. Gas assets, especially conventional gas, were for true contrarians. While worldwide oil prices have fallen 60% since their 2014 peak, diverse natural gas prices swing between USD 2 and 4/million Btu in the US, USD 8/million Btu in central Europe, and USD 15/million Btu for delivered liquefied natural gas (LNG) in Asia. Depending on your timing and cost structure, gas assets may be a rare highlight in your business in 2015.

Conventional wisdom implies that natural-gas demand will continue to grow, especially in locations where coal is being phased out, nuclear growth has slowed/reversed, and renewables remain a small and intermittent energy source for the foreseeable future.

The underlying fundamentals may tell another story: LNG plants in progress will increase supply by 122 million t/a by 2020, while LNG demand is expected to grow much slower. Even though more LNG import terminals will be completed in the next several years, global regas-facility utilization is only 33% of capacity. Because markets need to balance eventually, will demand grow to soak up the excess supply or will the new volumes be slow to come online?

In free and unregulated markets, the “invisible hand” first described by Adam Smith ultimately guides producers and consumers to a price and quantity that satisfy both parties. Unfortunately, oil and gas markets are far from free and unregulated, so investment time lag, regulations, and politics tend to delay and distort the inevitable balance that must exist in markets. Opinions on the outcome of all these competing factors tend to converge to a group consensus, which is usually just an extrapolation of “more of the same.” In 1986, we were all convinced there would never be another boom and the then-current bust would last forever. Thirty years, and several boom-and-bust cycles later, we are still making straightline projections, even though it is clear that the only thing that stays the same … is change. JPT

Recommended additional reading at OnePetro: www.onepetro.org.

IPTC 18050 Real-Time Blending Optimization in Upstream—Operating on the Edge by Claudia Zuluaga, Sarawak Shell, et al.

SPE 172528 Use of Technology To Enhance Gas Production in Saudi Arabian Carbonate Reservoirs—Key Enablers by Zillur Rahim, Saudi Aramco, et al.

SPE 173606 Post-Fracturing Gas Production Through Shale Capillary Application by A. Hayatdavoudi, University of Louisiana at Lafayette, et al.
A Novel Approach to Evaluate the Risk of Sanding for Optimum Well Completion Design: A Deep-Water Case Study from Southeast Asia
Authors: Younessi A. , Khaksar A.
Published: October 2016

Challenging environments, such as deep-water, require greater effort when designing wells and completion systems. In such cases, hydrocarbon production associated risks must be evaluated from very early stages of field development. Particularly, the risk of sanding should be investigated to select and define the optimum well completion, and if required, the appropriate sand control options. This paper presents a novel approach to predict the onset of sanding by describing a case study from a deep-water gas field in Southeast Asia.

Sanding analysis generally consists of either a numerical or analytical model calibrated against laboratory tests and production histories. Here, both numerical and analytical models are implemented to achieve a robust and reliable prediction in the absence of any production data. For this purpose, the numerical model is prepared and run using a comprehensive material model considering poroelastic-plastic rock behaviour with strain hardening. The rock is modelled from a combination of single-stage triaxial and advanced thick-walled cylinder rock mechanical tests on representative samples from the target reservoirs. A poroelastic analytical model calibrated against the numerical modelling results is then used to conduct sand production predictions with sensitivity analyses for a number of well trajectory scenarios for both cased and perforated, and open-hole completions.

Although the numerical and analytical models follow different assumptions, the sanding prediction results from both models are consistent. Once a reliable validation is obtained, the analytical method can be used with confidence for sand production prediction for future wells through its simplicity and fast realization of various scenarios. The results show that a high risk of sanding exists for both cased and perforated, and open-hole completion systems for the planned deviated wells. Hence, downhole sand exclusion options are deemed to be required for the development wells.

Incorporating analytical poroelastic and numerical poroelastic-plastic sanding evaluations enhanced the reliability of sanding prediction for development wells. This approach is particularly beneficial in the absence of production data at appraisal or early development stages.
Successful Sand Control Campaign for the Development of a Highly Heterogeneous and Multilayered Sandstone Reservoir in Indonesia: A Case Story Offshore Natuna Sea
Authors: Tsangueu Barbara , Wallace Cal , Ginting Job Roy , Sutejo Dian
Published: October 2016

The Natuna Sea in Indonesia contains highly laminated and partly consolidated sandstone, with a combination of highand low-permeability zones, requiring different types of sand control completions (frac packs or high-rate water packs). Previous operators developing the same area have used multizone single-trip completion tools to optimize completion time while tailoring the pumping treatment to each interval’s specific properties. Tailoring the pumping treatment has historically required operators to us rigs with ample deck space or vessels temporarily outfitted with pumping equipment to keep the flexibility of completion types for each zone. In this specific case study, the operator had different constraints but was able to successfully complete the campaign and to overcome the challenges operating from onboard a relatively small jackup rig. The challenges were addressed using an optimized skid-based pumping spread and exclusive carrier fluid technology. In addition, pumping design optimization was done through minifrac analysis to evaluate formation mechanical properties and fluid efficiency to ensure the successful placement of the final treatment. From the completion persepctive, the wells for this campaign were highly deviated, increasing the risk of early screenout due to proppant settling and high tortuosity. Rigorous onsite fluid QA and QC during operations eliminated risks of premature sand settling due to fluid quality, and prefracturing diagnostic tests and use of a low-concentration slurry stage enabled recognition of high near-wellbore friction pressures and then overcoming them when necessary. A total of 24 pumping stages comprised of 16 frac packs and 8 high-rate water packs were successfully placed in eight wells. The treatments used a carrier fluid whose properties were easily adjustable on the fly, enabling appropriate treatments for each zone within the limitations posed by the available equipment and the constraint to optimize completion time. As a main result, production targets have been exceeded by 57% versus initial expectations.
Identifying By-Passed Pay in Complex Water Flooded Reservoirs with Advanced LWD Measurements
Authors: Ge Shengquan , Ma Bin , Liu Fanglin , Li Ting , Liu Yanmei , Yang Xingwang
Published: October 2016

This study addresses the problem of fluid characterization in siliciclastic reservoirs where the resistivity contrast between pay and wet sands is low. Our study field contains connate water of extremely high salinity. The pay sands generally have high irreducible water saturation, which brings down the resistivity reading in oil zones. It is typically difficult to identify hydrocarbon zones with resistivity alone. The low resistivity pay poses a significant technical challenge for the development fields, because the operator must locate the by-passed hydrocarbon and understand the distribution of water floods in order to make future development plans.

The key to accurate fluid characterization in this challenging environment is a good knowledge of formation water salinity. Unfortunately, due to years of water injection to maintain production pressure, water salinity in these reservoirs is highly variable. In such environments, one cannot assume a fixed salinity value when applying saturation equations to well logs.

Thermal neutron cross-section (Sigma) is very sensitive to chlorine in the reservoir rocks and fluids and can be used to distinguish between water and hydrocarbon in a salty water environment. Since both Sigma and resistivity are dictated by water salinity, we can use these two inputs to simultaneously invert for the two unknowns, water saturation (Sw) and water salinity. This process avoids interpretation errors caused by uncertainty in water salinity and does a good job distinguishing bypassed hydrocarbon from water zones. Furthermore, we can use the inverted Sw and salinity to compute continuous hydrocarbon density, hydrogen index (HI) and viscosity downhole.

We applied the above technique to a set of LWD logs acquired in 4 horizontal development wells. We validated our computed water saturation with production history of these wells. The hydrocarbon fluids parameters, ie, salinity, density, HI and viscosity, are cross-checked with surface measurements on produced fluids.
Prediction of Capillary Pressure for Oil Carbonate Reservoirs by Artificial Intelligence Technique
Authors: Busaleh Yasser R. , Abdulraheem Abdulazeez , Okasha Taha
Published: October 2016

Several types of Artificial Intelligence (AI) techniques were utilized to predict capillary pressure in carbonate oil reservoirs with complex morphologies. To develop AI models that predict capillary pressure, a training data set is used that comprises of mercury injection drainage capillary pressure data. In this study, the training data included a set of 70% of 202 core samples that included porosity, permeability and grain density measurements from conventional core analysis tests. Models were developed using this data to predict capillary pressure. Using an error minimization routine, a comparison between the predicted results and laboratory measurements was used to show the validity of this analysis. The model was tested against a new dataset, the remaining 30% of the 202 core samples, that was not included in the training phase. This process was performed on mono-modal, bi-modal, and combined modal data sets.

The analysis of the AI models used in this study, showed that AI has promising potential; however, there is still room for improvement.

Capillary pressure data is one of the most critical parameters used in reservoir characterization and initialization stage of simulation models. Many reservoirs do not have an ample data for a comprehensive evaluation. This method utilizes a small core data set to derive models that can be used to predict capillary pressure in reservoirs that lack these measurements. This proposed approach has three advantages: saves time and money, does not require core samples for new spots in the same area, and uses the available results to their maximum potential from previously destroyed core samples. While previous work did not address the prevalent bimodality of the carbonate rock through the use of Flow Zone Indicator FZI / Rock Quality Index RQI, this paper addresses specifically the AI application to the different rock modals through Thomeer methodology.
Well Planning and Stimulation Optimisation by Integrating 3D Geomechanics for a Horizontal Well in the Northern Cooper Basin
Authors: Gui Feng , Rahman Khalil , Lockhart Duncan
Published: October 2016

Drilling and stimulation of exploration and development wells in the Cooper Basin, Central Australia, has been challenging over the decades due to the high-pressure, high-temperature environment, the high stress anisotropy, and the presence of thick coals. Most of the wells drilled to date have been vertical. To improve production, a study was conducted for a low-permeability tight-sand oil field to assess a horizontal well with multi-stage stimulation. The long horizontal well was expected to pass through a region with varying depletions and lithologies, causing lateral variations in stress and rock properties that could only be captured by a 3D geomechanical model.

A 3D geomechanical model was constructed to provide an integrated and accurate understanding of the field and to facilitate the planning and design of drilling, completion and stimulation of the horizontal well with reduced cost and risks, and to maximize the productivity. Based on detailed 1D geomechanical modelling, a well-centric understanding of the three principal stresses, fluid pressure and rock mechanical properties of the formations was developed for offset wells in the field. The pore pressure distribution and depletion in 3D space was calibrated using well test and long-term pressure survey data. Rock mechanical properties and stresses were populated in 3D space using seismic interval velocities and relationships developed in the 1D modelling, honouring the 3D static geological and structural models.

The model of pressure, stress and rock property variations in 3D space enabled optimization of the casing program and mud weights. Operational best practices to drill the long horizontal well, especially the high-angle build section in overburden coals, were compiled based on a drilling knowledge base developed using data from analogous fields. The use of varying stress and rock mechanical properties along the planned well trajectory in hydraulic fracturing optimization was a differentiating approach to conventional hydraulic fracturing optimization using 1D geomechanics. The treatment was optimized to confine the fracture above the water-bearing formation along the well path. The optimized stimulation design provided the best solution of stages, proppant and fluid selection, and injection schedules to maximize production with minimum cost.

Based on the detailed assessment, it was concluded that the horizontal well is drillable with optimized mud properties and good drilling practices to overcome the instability in coals. In addition, the reservoir section can be drilled safely with lower mud weights whilst still maintaining good wellbore shape. A multistage transverse fracturing program was optimized to improve the production, mitigating the challenges from the extremely low stress contrast between reservoir and the underlying water-bearing zone.
Uncertainty and Risk Management: Waterflood Pilot Design and Surveillance Proposal for a Giant Multi-Layered Sandstone Reservoir
Authors: Wei Chenji , Li Yong , Song Benbiao , Tian Changbing , Li Baozhu , Zhou Jiasheng , Zheng Jie , Luo Hong , Lan Jun
Published: October 2016

Accurately understanding the geological and dynamic characteristics determines the recovery and life cycle of a reservoir. Several uncertainties and risks exist during the development especially for giant multi-layered sandstone reservoirs. Pilot is one of the most effective steps to manage risks and reduce uncertainty, which help better understand the reservoir, expose the conflict during development, propose corresponding surveillance plan, determine development plan, and eventually improve the reservoir performance.

This study focuses on a giant Cretaceous multi-layered sandstone reservoir in the Middle East, which started to produce since 1960s without any energy supply, and the current reservoir pressure is approaching the bubble point pressure. Therefore, water flooding is urgently needed. In order to reduce uncertainty and risks, criteria and workflow of selecting waterflood pilot is proposed by integrating the geology, dynamic data, well status, and existing facilities etc.. 4 pilots are selected and each pilot represents a typical reservoir type to better understand the performance and adaptability of different development plan. Each pilot has its own specific objectives and detailed operation plan. Finally, surveillance plans are proposed based on geological understanding, dynamic behavior, and simulation results.

According to the proposed criteria and workflow, pilots are selected to represent good, medium, and poor reservoir quality respectively. Pilot I is selected as an example to be discussed in detail. The reasons to select this pilot, well pattern and spacing, and perforation strategy discussion are presented. Finally, surveillance is divided into different groups, and implementation plan of different types of surveillance is determined.

This study offers a comprehensive case study that supports the engineers and geologists for better understanding the reservoir and optimizing waterflooding plan for this reservoir. Moreover, it offers an integrated methodology of pilot selection and surveillance proposal for other similar oilfields.
Field Trials of Plugging Oil and Gas Wells with Hydrated Bentonite
Authors: Towler Brian F. , Firouzi Mahshid , Holl Heinz-Gerd , Gandhi Randeep , Thomas Anthony
Published: October 2016

Many field trials have been conducted to explore the effectiveness of using hydrated bentonite as a sealing material for plugging and abandoning (P&A) operations of oil and gas wells. Many of those trials are reviewed here, including trials in Texas, New Mexico, Oklahoma, Wyoming and Queensland, most of which have not been previously reported. All of these trials have been successful, even though a few wells have been eliminated from the programs because they were found to be unsuitable. In most jurisdictions regulation changes are necessary to allow bentonite to be used in order to plug wells. This has been done in California, Texas and Oklahoma. In Wyoming it is currently permitted as the bottom plug in coal-bed methane wells. In Queensland a field trial has been allowed under the experimental materials clause in the regulations.
Reducing Emissions From Oil & Gas Facilities By Use Of Field Proven VOC Tecnology
Authors: Salomone Sara
Published: October 2016

The focus has been to reduce or remove the need for flaring, but very little attention is given to another major cause of greenhouse emission; the venting of pure hydrocarbons from Oil & Gas Facilities especially from FPSO, FSO and trading tankers.

Floating Production Storage and Offloading (FPSO) and Floating Storage and Offloading (FSO) units commonly use inert gas as a blanket gas of the crude oil during offloading of the storage tanks. The inert gas is generated by burning fuel oil or diesel and consists mainly of CO2 and N2 while CO and NOx are side products. During offloading of oil, the displaced volume of liquid is replaced by the generated inert gas to avoid ingress of air (Oxygen) and to keep a slight overpressure inside the storage tanks. When producing or transferring the crude oil, the oil displaces this gas, which is normally vented, resulting in a direct release of hydrocarbon gas to the atmosphere. During these operations, the inert gas is in contact with crude oil. Due to the difference in composition between the gas and the liquid phase, hydrocarbons flash into the inert gas atmosphere. The result is a gas mixture containing up to 80% hydrocarbon gases (methane and heavier components) at the end of a loading cycle. This mixture made of VOC, CO2 and N2 is normally vented directly into the atmosphere. The main component of the VOC is methane, which is a greenhouse gas with Global Warming Potential (GWP) 20 times higher than CO2.

Routine flaring releases CO2, NOx and CO, which are precursors of the ground-level ozone. The ozone at the higher altitude of the Earth's atmosphere (Stratosphere) creates a layer which absorbs the ultraviolet radiations. However, the so-called ground-level ozone (Troposphere area) is toxic and dangerous for health and environment.

Routine flaring and venting form personnel health hazard in addition to cause gas alarm trips with likelihood of subsequent production upsets/shutdowns.

The technology to recovery these emissions has been in use since 1994 on the Norwegian continental shelf. It is also used on shuttle tankers and onshore plants. Recovery of VOC emissions can easily be combined with the recovery of routine Flaring Gas, re-routed into the process and utilized further.

The technology has contributed to substantial reductions of VOC emissions on the Norwegian continental shelf over the last 20 years. Today, an increasing number of oil majors and governments require introduction of both VOC and Flare Gas Recovery, recognizing the major importance of emission reductions both from an environmental and from an economic point of view.
Characterization of Elastic Properties of Lacustrine Shale Reservoir Using Well Logging and Core Analysis
Authors: Yu Hongyan , Wang Zhenliang , Rezaee Reza , Arif Muhammad , Xiao Liang
Published: October 2016

Understanding the elastic properties of rocks is very important for unconventional reservoirs exploration. Unlike marine shale, the lacustrine shale is more complicated with complex mineral composition and frequent sand and shale interbeds. Typical analysis for lacustrine shale gas reservoir rock include: triaxial test, X-ray diffraction (XRD), total organic carbon (TOC) measurements. The mineral composition is different for argillaceous shale and silty laminae shale. The static elastic properties are controlled by clay content, organic matter and porosity. In this work we evaluate elastic properties of above mentioned rocks using experimeal core analysis and well log data. Based on triaxial test, Young's modulus and Poisson's ratio of rocks are obtained by means of the relationship between strain and stress. Argillaceous shale is low to medium strength rock, and silty laminae shale belongs to medium to high strength rock. We find that Young's modulus and Poison's ratio has a negative relationship with clay content, organic matter and porosity which is present by bulk density and neutron porosity logs. The dynamic elastic properties are obtained from cross diploe acoustic well logging data. The dynamic elastic properties have the same controlling factors as static properties. Argillaceous shale and silty laminae shale have significantly different response characteristics in well logging. The porosity is the main factor which leads to the differences between dynamic and static elastic properties. Moreover, it is also found that the ratio of static and dynamic elastic properties is a function of porosity. Hence, density porosity and neutron porosity from the logs are chosen to establish dynamic elastic properties correction model. The correction model is effective in predicting static properties in lacustrine shale gas reservoirs. We conclude that the static properties obtained from the correction model match with core derived static properties.
Comprehensive Geomechanical Modeling and Wellbore Stability Analysis for Infill Drilling of High-Angled Wells in a Mature Oil Field
Authors: Asadi M. S. , Khaksar A. , Ring M. J. , Yin Yin K.
Published: October 2016

Reservoir pressure depletion and decline of production are two common features of many mature petroleum fields. Drilling and stimulation of long, highly-deviated wellbores is one of the many technologies commonly used to enhance the production in mature fields. Reservoir depletion results in reduction of in situ horizontal stresses and more specifically in the formation fracture gradient (FG). The presence of non-depleted and generally weak interbeds within the pressure depleted reservoirs with a low FG leads to a narrow drilling margin for new infill wells or laterals. Therefore, a robust knowledge of rock mechanical properties, formation pressures, the magnitude of in situ stresses and their evolution with production and depletion are essential for successful drilling of new wells in particular and the redevelopment of mature fields as a whole.

A case study from a mature oil field in the Sarawak Basin, offshore Malaysia, is presented where the field geomechanical elements were constrained from field data acquired in more than 10 offset wells drilled in early 1980s, and a new re-development well drilled in 2014 with supplementary core, well logs and pressure data. The results of rock mechanical core tests along with acoustic logs in the new well were used to update and verify an early geomechanical model built in the area. Extensive production from more than 20 multi-layer sandstone reservoirs resulted in significant pressure depletion whilst some of the deeper and stronger reservoirs still contain significant oil reserves. The geomechanical model was used to identify the narrow-margin drilling and stability risks of infill deviated oil producers targeting by-passed oil in the deeper reservoirs, and horizontal water injectors planned to enhance oil recovery in the field.

The results showed that both intermediate and production sections of planned wells would have narrow mud weight windows. Depending on the well trajectory, the production sections could have only 0.8 ppg drilling margin due to a higher depletion of deeper reservoirs. The analyses also highlighted thin, weak interbeds in the intermediate hole section that require a minimum mud weight of 10.0-10.5 ppg to limit shear failure to a manageable level considering hole cleaning challenges in high-angled wells whilst the FG of depleted sections could be as low as 11.3 ppg requiring stringent control on downhole pressure while drilling to keep the hole pressure within the safe margin. Optimum mud weights, safe drilling margins and casing setting points were determined for nine different well trajectories focusing on the azimuthal and inclination dependency of fracture and borehole collapse pressures.

The subsequent drilling campaign of planned infill oil producers and water injectors in the field has been successful due to good drilling practices, using the recommended mud programs consistent with wellbore stability assessments, and careful bottomhole pressure control.
Produced Gas Utilisation Strategy Study on Low Permeability Reservoir CO2 EOR Process
Authors: Lv Wenfeng , Yang Siyu , Yang Yongzhi , Yang Shenglai , Ma Xiaohong , Li Shi , Wu Chunrong , Hao Mingqiang
Published: October 2016

In the late 1990s, large amounts of low permeability resource plays in the south of Songliao basin have been discovered and made a great contribution to regional development, so far most of them need to be made efforts to improve recovery factors by tertiary method, CO2 flooding has an effective way for this kind of reservoir. CO2 injection pilot was implemented in 2008, it provided invaluable information for extensive areas to make gas injection and production scheme including produced gas recycling.

Most low permeability reservoirs in Song Liao basin have no nature flow, the economic productivity could not be obtained except fracturing. Therefore, it leads to CO2 breakthrough early and produced gas profile variation greatly during the CO2-EOR process. CO2 is from the deeper natural gas field with CO2 concentration over 20%, after separation, the CO2 purity reaches 99% for injection. So how to treat the EOR produced gas is an environmental and economic issue to achieve zero emissions for the whole operations. According to the actual field test data, the vast majority of composition of produced gas are lighter hydrocarbon and CO2. This paper will analyze the composition of gas samples from Jilin oil field, understanding the components of the output gas variation with time. The phase behavior and mass transfer will be characterized by the minimum miscibility pressure (MMP) test and core flood experiment, and the quantitative description method will be obtained through the relationship between the individual component or segment components and sweep efficiency.

Consideration the effect of CO2 impurities on MMP and displacement efficiency, the critical value of CO2 concentration of produced gas is 85%~95%, according to this study, all the produced gas can be reinjection without separation, the value for field application is approximately 90%. That means it would require mixing with pure CO2 for reinjection when CO2 concentration of produced gas is below 90%, otherwise, it could re-inject to oil field directly.

All these results have been applied to achieve reasonable CO2 recycle.
Issues and Challenges with Controlling Large Drawdown in the First Offshore Methane Hydrate Production Test
Authors: Sakurai S. , Nishioka I. , Matsuzawa M. , Matzain B. , Goto A. , Lee J. E.
Published: October 2016

The first offshore methane hydrate production test was conducted in the Eastern Nankai Trough area of Japan in 2013 subjecting gas hydrates reservoir to large drawdowns by reducing bottomhole pressure (BHP) for in-situ dissociation of gas hydrates. This pioneering test has proven the feasibility of depressurization method through demonstration of gas production from a deep water gas hydrates reservoir. Approximately 119,500 Sm3 of gas was produced during a continuous flow period of 6 days. However, reservoir response to a range of drawdown conditions was not possible due to unintended water production through gas line. This paper evaluates the issues with drawdown control that was affected by the water production.

Gas and water released from the dissociation of gas hydrates were separated using a downhole gas separation system. The separated gas and water were produced to surface via two dedicated gas and water lines. Drawdown was planned by pumping out water into the water line using an electrical submersible pump (ESP). Drawdown control was designed to regulate the liquid level (or hydrostatic pressure) in the gas line by controlling the ESP frequency as well as the water line surface backpressure.

Analysis of production data supported by flow simulations indicated that water production through the gas line was the main reason for the loss of drawdown control, i.e., the rising of liquid level was due to water production caused by the produced gas. Water entrainment by gas stream was not the main reason for the water production due to low gas velocity. The produced gas lightened the water column in the gas line, raised the liquid level and lowered the BHP. This process mimics a gas lifting process in a predominantly liquid production well. Since the BHP was largely affected by the liquid holdup as well as the volume of gas in the gas line, it was difficult to regulate the drawdown as intended.

The analysis concluded that water production through the gas line could be prevented if a backpressure regulator was installed at the surface gas line and / or the ESP had high tolerance to the presence of free gas. Lessons learnt from this first field trial has provided valuable information for improving the methods for controlling large drawdown in methane hydrate production system.
The Fracture Behavior in the Vicinity of Interface Based on the Digital Speckle Experiment
Authors: Suling Wang , Chunlei Xing , Deshi Zhang , Chongquan Shao , jian Jiao , Kangxing Dong
Published: October 2016

Rock stratification develops widely in unconventional reservoirs, and it increases the non-uniform of the reservoir on vertical. The interfacial slip deformation can alter the fracture shape when it encounters the weak stratification or the natural fractures, so the rock stratification play an important role in the fracture propagation.

In this paper, the crack extension experiment about the interface is established through the three-point bending. The digital speckle measurement technology was used in order to observe the change of the strain field, near the interface layer, in the process of cracks through the interface. At the same time, based on the maximum circumferential stress criterion, an interfacial slip model has been developed, and the extended finite element method which can reveal the distribution of stress and strain on the interface has been used in the numerical realization of the model. The numerical results of the strain field agree well with those of experiments.

The experiment and numerical simulation results show that when a crack propagates the interface, the crack will break through the interface, or crack kink in the interface, or crack extend along the interface. The reason of the crack deflection, when a crack goes through the interface, is that the crack tip occurs blunt, and the crack length does not increase while the width increases. The tip blunt causes the interfacial shear strain which can turn the direction of the maximum circumferential stress. The crack deflection angle is affected extremely by the interface strength. The weaker the interface is, the greater of crack tip blunt is and the bigger the shear strain of the interface is, which cause the crack deflection angle increase. Based on the above analysis, it indicates that the blunt of crack tip in the interface is the mechanical cause of the crack to change direction extension. The weak bedding is the important factor causing the complexity of unconventional reservoir fracture morphology.

This can be used as one of the standards to evaluate the fracturing effect of unconventional reservoir.
Application of a Continuous Personal Development Methodology
Authors: Boles Jeanne
Published: October 2016

WOCRM is based on the Crew Resource Management (CRM) training program developed in the aviation industry in the 1980's. It is an attitudinal and behavioural training methodology; used to continuously engage the crews in repetitive, hands on and interactive exercises and simulations, providing structured feedback to develop each crew members’ non-technical skills. The training was first developed for airline cockpit crews in the 1980's and has since flourished within commercial and military aviation, mining and medical industries. A review done for Qantas by David Hainsworth, (Briefing to Qantas safety management, 2000) indicated that 96% of their LTI's root causes were behavioural in nature.

According to Edkins (2002), it follows that if we agree that the focus of CRM is to modify and reinforce effective safety Behaviour, it is reasonable then to assume that LTI's will be reduced. If LTI's are reduced, so too then is the costs associated with them, which in Oil and Gas can go into the billions and so a very good Return on Investment (ROI).

Focusing on Oil and Gas, the IOGP reports clearly indicate that Well Operations Crew Resource Management (WOCRM) training is required and that it should be incorporated into the mandatory International Well Control Forum (IWCF) and International Association of Drilling Contractors (IADC) Well Control Training. This is all well and good, however, if anything is to be learned from Dr Graham Edkins, (The state of the nation: How mature are HF/NTS programs within the Australian Airline Industry?, 2012) training alone is not enough.

From a psychological standpoint, to change or correct a Behaviour takes 66-270 days of repetition and constructive feedback. Therefore, the new Behaviour, process or procedure must be repeated for at least 3 months, to ensure that the Behaviour or procedure will in fact be applied when needed, especially in a stressful situation. This then implies the need to add coaching techniques to the methodology, which this paper will introduce.

The major benefit to Oil and Gas, is that all of the techniques mentioned herein have already been created and developed, and our Industry simply has to apply the lessons learned from those that are more advanced, to create a continuous personal development methodology to reduce Lost Time Incidents (LTI's) caused by human error, which would have a potentially massive effect on the financial loss associated with these errors, concluding that this methodology could have a very impressive Return on Investment (ROI) for companies large and small.
Separate Layer Water Injection for Offshore Directional Wells
Authors: Fuchao Sun , Deli Jia , Jiaqing Yu , Xiaohan Pei , He Liu , Lichen Zheng , Shujun BAO
Published: October 2016

The IOR is permanently issue for oil development. Zonal Water Injection Technology is a key technic about IOR. The zonal water injection technology faces several challenges for offshore oil field, such as numerous highly-deviated wells, complicated inter-layer contradiction, high cost, low operation efficiency, etc. High efficiency, low cost and low risk are crucial targets for offshore water-flooding. To achieve this target, CNPC developed a new offshore water injection technology featuring bridge concentric structure. It can realize multi-layer flow rate testing and adjusting efficiently and accurately with low cost and low risk. The system is composed of downhole bridge concentric regulator, downhole control instrument and surface control equipment. It can obtain multiple downhole critical parameters on line such as layer flow rate, tubing pressure, formation pressure and temperature. Also it can realize downhole flowrate dynamic adjustment automatically with no need to run and fish downhole valve. A steel cable with single core is employed for two-way data transmission. Concentric connection and adjustment between regulator and instrument is adopted to ensure successful connection for offshore deviated wells. The eccentric valve is designed as a innovation point with low leakage and low regulation torque. High-precision electromagnetic flow meter is employed to obtain layer flow rate directly to ensure test accuracy in deviated wells. Until recently, this technology has been applied in eleven wells including five in jidong offshore highly-deviated wells with maximum deviation 55 degree, maximum pressure 50MPa and maximum temperature 120 degree. The application successfully achieved the parameters of flow rate, tubing pressure, formation pressure and temperature. Besides it realized flow rate adjusting automatically. The whole process of water allocation and packer seal test were finished on line and the efficiency was significantly improved.