bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Development and Monetisation via Floating Facilities FLNG, FCNG, FGTL and FSRU
Authors: Yussoff Ir. Ikhwan
Published: November 2020

The PETRONAS Floating LNG concept was envisaged to monetize stranded gas resources. At the same time, PETRONAS has also exploring the development of Floating Compressed Natural Gas (FCNG) and Floating Gas to Liquids (FGTL) as part of the "Technology Challenge Initiatives". In completing the elements in the overall LNG value chain, an FSRU will also become one of the fast track method to import LNG especially to the non-LNG importer country.

The two floaters namely PFLNG1 & PFLNG2 was built by PETRONAS to monetize the gas for offshore Sarawak and Sabah respectively which in turn increased the country's LNG production capacity. As part of the aim to commit to green house or flaring mitigation, PETRONAS is also gearing up towards the evaluations of miniscale Floating CNG vs Floating GTL. On the supply side, the development of Floating Storage Regasification Unit (FSRU) is believed to be an added value to PETRONAS as one of the biggest LNG exporter in the world.

The fast track nature of the project presents a challenge to the Gas and Upstream Business in meeting the target date. The advantages of having a floating facilities as a solution to monetize the stranded gas field and mitigating the flaring/venting activities will be covered considering the risk identified throughout the development phases. The important of front end engineering has led to a fit for purpose design and excellent construction methodology.

The famous debate with regards to offshore vs onshore gas development will be revisited aligned with the technology maturity and market availability. Speaker will review the new facilities as a viable option in the future for any gas developments requiring a quick solution. Extensive technology selection exercises were conducted in finalizing the turret mooring, gas treating, liquefaction, regasification, cargo containment and offloading systems.

Designers and licensors have done rigorous design optimisation and marinization studies on impact of floater motion where it was evaluated against an extensive list of criterias. Specific offshore and marine technology selection for the facilities will be discussed in the effort of realizing the aim to bring conventional gas facilities to offshore environment. Speaker will share the challenges in selecting the right equipments in order to suit the condition including sea state, weather and regulatory requirements.
Multistage Cementless Acid Fracturing in Sidetracking Slim Hole using Innovative Packers with Anti–Corrosive Thermo–Plastic Vulcanizates
Authors: Tong Zheng , Liu Shun , Zhang Weiping , Ye Qinyou , Liao Chenglong , Qian Jie
Published: November 2020

Most 5 1/2in-casing mature wells need to be re-fractured for improving the ultimate recovery. Over the last decade, operators focused on the sidetracking well completion for maximizing wellbore contact. Acid fracturing tend to be performed to treat the reservoirs and make fractures system more complicated as much as possible. The irregularity of slim hole has negative influence on the deploying of completion or fracturing assembly. Isolation tools are usually subjected to heavy corrosion caused by acid or proppant fluid.

The 3 1/2in Open-hole packer-sleeve (OHPS) completion assembly including improved external casing packer (ECP) were proposed for sidetracking well completion. The water-swellable packers (WSPs) with anti-corrosive thermo-plastic vulcanizates (TPVs) was used as the alternative to current mechanical-set ECPs. The TPV matrix was prepared by physically blending high-strengthen carboxylated nitrile (XNBR) with polyamide (PA6). To improve the swelling performance, newly-developed Porous Super Absorbent Resin (PSAR) was mixed and distributed into XNBR/PA6 system. The new swellable TPV exhibits the advantages of high strength, anti-corrosive property and high reliability over traditional packing materials. The TPV material characterization and annular sealing test of 3 1/2in prototype was conducted in the lab.

One 5 1/2in mature oil well was selected for field validation. One 3 1/2in OHPS string with four stages was successfully tripped into large-deviated slim borehole. During the stimulating operation, WSPs acted as effective barriers and any communications between stages did not occurred. It is concluded that the new OHPS using improved WSPs meet requirements of slim-hole sidetracking well completion and stimulation.
Corrosion Resistant Alloy Pipeline: Creating Knowledge Behind the Scenes
Authors: A Razak M. Hasbi , Mukhtar Nur Izyan
Published: November 2020

The high pressure high temperature (HPHT) with significantly high contaminants of CO2 and H2S in full well stream demands the selection of Corrosion Resistant Alloy (CRA) pipeline for an offshore gas field. This pipeline system comprises of metallurgically bonded CRA layer produced by roll bonding called Metallurgical Cladded Pipe (MCP) and mechanically expanded and fitted CRA layer in a backing steel called Mechanical Lined Pipe (MLP). This paper outlines specific issues, mitigations and lessons learnt encountered during development phase of the CRA pipeline. Several issues arise during manufacturing and installation of the pipeline such as undulation appearance and rise indications at MLP internal surface, fit-up and girth welding constraint at the pipe end of MLP and MCP during installation phase. Thorough investigation including various inspections and testing on sample pipes were conducted to find the root causes and mitigations to ensure the integrity of the pipeline throughout the operating life. The investigation involved special tests such as pipe coating simulation and non-destructive testing (NDT) on the affected pipes. Specific procedures were developed to address the constraints based on the outcome of the investigation. Findings based on thorough investigations demonstrated that MLP and MCP are able to satisfactorily meet design requirements for the pipeline. Lessons learnt and best practices were also established for future reference in the manufacturing and installation of CRA pipeline.
Calculating the Initial Spare Parts Inventory in Petroleum Projects with Cost-Benefit Analysis
Authors: Kusumawardhani Mayang , Markeset Tore
Published: November 2020

The first year of operation is a crucial period after the handover of a petroleum facility from the project phase. To minimise downtime and costs, it is essential to anticipate equipment breakdown, and one of method is to have spare parts readily available. There are studies on spare parts inventory forecasting based on the amount of historical operation data or condition-monitoring data. However, determining the initial spare parts inventory of a petroleum facility with limited historical data is a challenge, and often in the project phases the information is not comprehensive enough to support the decision-making. Thus, the paper will propose a decision-making method for the initial inventory of a new petroleum facility.

The proposed method aims to simplify the spare parts assessment, defining the affecting parameters and simplifying the means to evaluate them. The result shows a means for determining the affecting parameters for various situations, as well as for ranking the criticality. Especially for the initial project condition or in events where data is not readily available, the current industry practices will be presented to mitigate the lack of information in the assessment. Finally, a case study is presented to show the application of the framework in two new petroleum projects.
Engin Engineering Added Value with Application of Stochastic Fatigue on the Offshore Floating Units
Authors: Bamdad Mehrdad
Published: November 2020

Stochastic fatigue approach has been presented for the topside process platform structure on floating units such as FPSO and FLNG. The methodology implies that the topside and hull structure are modeled in an integrated model and solved through finite element hydro-structural solver. With reference to a real project, the result compared with simplified and more conservative approach demonstrating the engineering added value with a fit for purpose methodology.

With full integrated model, the correct capture of inertia and deflection and considering wave spectra applied to the response function in full range of applicable waves, a proper fatigue damage for each probable wave calculated which in sum concludes about the total fatigue damage with neither any fatigue contribution overlooked, nor any unnecessary conservatism taken. Such approach is very effective to find out real critical fatigue spots helping for an effective engineering effort and schedule target achievement.

The full practical workflow involving naval and structural discipline is presented and with reference to a real project experience which implemented the presented methodology, the effectiveness to narrow down the fatigue concerned spots are reviewed. Meanwhile some hints about susceptible spots subject to fatigue on a floating production unit are provided.

The workflow as proposed aims to connect and integrate naval and structural expertise using synergy between offshore and shipbuilding industry. Meanwhile the results of the proposed method will provide more clarity about the effects of integrated modeling and stochastic fatigue method for the offshore floating units.
A Novel Semi-Analytical Model for Highly Deviated Wells in Fractured-Vuggy Carbonate Gas Reservoirs
Authors: Wang Kongjie , Li Zhiping , Wang Lian , Shi Hua , Adenutsi Caspar Daniel , Wu Junda , Wang Chao
Published: November 2020

The study of pressure transient behavior in fractured-vuggy reservoirs has recently received considerable attention because a number of such reservoirs have been found worldwide with significant oil and gas production and reserves. In recent years, the use of highly deviated wells (HDW) is considered an effective means for developing this type of gas reservoir. However, in many fractured-vuggy reservoirs unexpected high gas production have been observed which cannot be identified with pressure transient models of horizontal well with pseudo state triple-porosity interporosity flow. This paper presents a semi-analytical model that analyzed the pressure transient behavior of HDW in triple-porosity continuum medium which consist of fractures, vugs and matrix. Introducing pseudo-pressure, Laplace transformation and Fourier transformation were employed to establish a point source and line source pseudo-pressure solutions in Laplace space. Then the pseudo-pressure transient curve was got by numerical inversion. Furthermore, the flow characteristics were analyzed thoroughly by examining the curve which is mainly affected by inclination angle of HDW and interporosity flow coefficients between different pore media. Sensitivity analysis on the pressure transient behavior was performed by varying some important parameters such as the inclination angle, fracture storativity ratio and interporosity flow coefficients. Finally, a field case was successfully used to show the application of the presented semi-analytical model. With its high efficiency, this approach will serve as a reliable tool to evaluate the pressure behavior of HDW in fractured-vuggy carbonate gas reservoirs.
Energy Recovery from Offshore Facilities Water Disposal System
Authors: Duarte Leandro , Dellinger Guilhem , Dellinger Nicolas , Vazquez José , Heme-De-Lacotte Luc , Tcherniguin Nicolas
Published: November 2020

Currently, most of offshore platforms are equipped with gas turbines to fulfill their power requirement and consequently produce CO2 emissions as a by-product. The energy efficiency of the asset is a key factor in reducing their carbon footprint impact. Numerous ways can be considered within the process and utility systems to improve the energy balance.

This paper will investigate the possibility to exploit the available hydraulic energy onboard offshore platforms to transform it into electrical energy. Part of the recoverable hydraulic energy is found in pressurized pipes where the flow is in charge or in other words under hydraulic pressure. The aim is to develop a novel turbine that will be optimized for water disposal energy recovery on offshore platforms. Hence the objective is to install a turbine to replace a conventional valve to maintain and regulate the pressure as well as generating electricity.

In close collaboration with TechnipFMC, ICube laboratory (Strasbourg, France) is completing a development program for such an hydraulic turbine. This paper describes some outcomes of this comprehensive study performed by experimental engineers and researchers in the hydraulic discipline with the support of engineering integration by TechnipFMC.
A New Method of Calculating Dynamic Reserves for Abnormally High-Pressured Offshore Gas Fields Early Stage Development
Authors: Wang Shuai , Zhang Jinqing , Tan Xianhong , Zhang Shaohui , Liu Yang , Li Yuwei
Published: November 2020

Dynamic reserves calculation is an important basis in the process of abnormally high-pressured offshore gas fields development. Based on the early stage development experience in abnormally high-pressured gas fields, the calculated dynamic reserves will be larger than the actual value. And the number of development wells in offshore gas fields is relatively small, which makes it more difficult to accurately calculate dynamic reserves. If the gas fields development dynamic was not acquired in time, the gas fields development adjustment would not be made effectively. Therefore, how to calculate the dynamic reserves accurately in the early stage is the key for this type gas fields development.

In this paper, a new method of calculating the dynamic reserves for abnormally high-pressured offshore gas fields early stage development has been put forward. First of all, the complete dynamic reserves prediction model was established with the use of material balance method. Secondly, in the process of model solving, the calculation model of effective compressibility coefficient was modified for the first time without laboratory experiment. Moreover, in order to improve the calculating precision of the early stage development dynamic reserves, the quality control model was established and the R factor was introduced.

The accuracy of dynamic reserves calculation is determined by the production data, pressure data, R value, etc. The greater R value is, the higher the accuracy is. When the R factor is between 0.9 and 1.0, the result of dynamic reserves calculation is right. Otherwise, we need to recalculate the input data. This new method has been applied in the early stage development of X abnormally high-pressured offshore gas field, and the calculated dynamic reserve is 186.66Bcf. If using traditional method, the dynamic reserve is 293.20Bcf, which is 36% larger than the new calculated dynamic reserve. The reservoir dynamic test data and geological static data have shown that the result of using this new method is more reasonable.

This paper provides a quantitative and operational new method to accurately calculate the dynamic reserves in abnormally high-pressured gas fields, and can guide the early stage development adjustment effectively.
Unconventional Tight Sand Oil: Breaking the Evaluation Barriers
Authors: Sharma Shivam , Ali Ahmed Moge , Pandey Shashank , Sharma Lovely , Aggarwal Akshay , Jha Amay , Gondalia Ravi , Suyal Shilpa , Shah Bhavik , Joshi Parth , Satyanarayana Ambati , Shaikh Moulali , Raman Ravi
Published: November 2020

Mesozoic age Golapalli sands are found in the Krishna Godavari Basin, located in the East coast of India. These sands are highly prospective for hydrocarbon exploration and development. They comprise of syn rift sediments, often, exhibiting low permeability. In general, these reservoirs do not flow naturally without hydraulic fracturing. Oil presence in Golapalli sands has already been proven in the basin from the exploratory wells. However, conventional saturation modeling using basic petrophysical logs has proved futile in establishing a definite oil water contact (OWC). This adds further complexity in the reserve evaluation and the hydraulic fracturing design. Moreover, the field is divided into multiple fault blocks with localized OWCs.

During the initial appraisal phase, wells that were hydraulically fractured produced oil with high water cut. This prompted re-evaluation of saturation modelling with 3 further appraisal wells. All new wells were selected at different fault blocks within the field and were to be drilled as slim holes of 5-7/8in diameter in reservoir section. Potential intervals with natural fractures were successfully evaluated using advanced sonic data. Zones of interest were selected integrating the fractures network identified with advance sonic measurements and high porosity values obtained from basic neutron-density logs. To constrain inversion resistivity-based saturation modelling, a new workflow was adopted to determine reservoir fluid movements prior to hydraulic fracturing in less than 0.05mD formation.

Through this approach, fluid saturations were successfully evaluated using a deterministic downhole fluid identification which helped in reducing saturation uncertainties while demarking the transition zone between oil and water in 0.05mD formation. With known oil zone identified, advanced sonic measurements were used to design effective hydraulic fracture models. A successful hydraulic fracture was initiated with excellent oil production with significantly reduced water cut compared to previous wells.

In this paper, a novel workflow will be presented that will help in characterizing fluids in tight sands (permeability less than 0.05mD). This workflow integrates the basic openhole logs and formation testing with conventional resistivity-based saturation modeling to accurately pinpoint the OWC in the tight sands. This workflow has applicability in unconventionally tight reservoirs where there is uncertainty in fluid saturations or fluid contacts. Through this methodology, the propagation of hydraulic fracture into the water zone can be prevented which will greatly help in reducing the water cut in such conditions.
Delineating Hydrocarbon Response using Robust Bulk Modulus Inversion Through Linearised AVO Approximation
Authors: Mad Sahad Salbiah , Merghani Arshin S. Boshara , Abdul Rahman Ahmad Sharif , Ghazali Ahmad Riza , Jaya Makky Sandra
Published: November 2020

The key to further demonstrate 4D values in Field A relies on the interpretation of the reservoir changes due to production from year 1995 to 2006. Significant rock properties change due to pressure and fluid movement showed different amplitude variation with offset (AVO) behaviour on seismic data at different vintages. Existing AVO indicators suggest ambiguous results prone to certain factors such as porosity. Fluid properties such as oil and water of density has similar range of values. Hence, differentiating oil versus water in the porous media has become a problem typically in exploration prospecting and production monitoring. This problem can be mitigated if we are able to estimate accurately the bulk modulus parameters since it differs between the properties in the pore-fluid phase and rock-solid phase of homogeneous media. Since the conventional fluid factor (f) provides ambiguous results prone to the instability of pore fluid mixture and porosity in identifying fluid prospect, we re-parameterized new AVO approximation in term of K considering bulk modulus of the rock matrix higher than the bulk modulus of the effective pore fluid (combine with porosities higher than 15%).

Then, the inverse problem is solved using conjugate gradient optimization and tested the robustness of the new method on thin channelized synthetic model and real field data. The synthetic result shows the inverted pore fluid bulk modulus is closer to the measured model and the initial model, however larger uncertainties was observed from inverted density compared to the measured model. Starting from the noise free scenario, we gradually added noise from 5% to 30% into the channelized synthetic model to ensure the quality of the inversion method. Field data example revealed that 4D inverted effective pore-fluid bulk modulus are capable to identify lateral waterflood sweeping effect in the reservoir after eleven (11) years of production, expand the ability in differentiating fluid for clastic reservoir hence increase the probability for accurate hydrocarbon prediction.
Survey Performance of Deeply-Towed Marine Seismic Vibrator with Post-Survey Processing Optimized for Deeply-Towed Survey
Authors: Ozasa Hiroaki , Asakawa Eiichi , Murakami Fumitoshi , Takekawa Junichi , Mikada Hitoshi
Published: November 2020

We have developed deeply-towed mechanical driven marine seismic vibrator (MSV) for the use in time-lapse seismic reflection survey to monitor offshore hydrocarbon reservoirs, in which interstitial fluids move with the production, for the optimization of recovery. For this objective, we evaluate the survey performance using MSV and revisited the data processing.

A downsized MSV was manufactured to conduct a sea trial to evaluate the performance as a seismic source in a real 2D seismic line survey off the coast of the Japan Sea. We compare the processed results (a) for the data acquired by a downsized MSV and (b) for that acquired by a 480 cu-inch airgun array. We then tried to improve the data processing for data acquired by the downsized MSV that was towed at a water depth which any conventional airgun could not be fired to see if the signal-to-noise ratio is improved.

We verified the survey performance using deeply-towed MSV and our data processing approach could be equivalent to it of airgun array the maximum seismic emission power of which is about 40 dB larger than that of the downsized MSV. Downsized MSV which was towed 50 m below the sea surface could acquire a conventional 2D seismic survey data with a conventional streamer cable. The superposition of long-leg surface multiples was observed in the data acquired by deeply towed MSV as anticipated. Our MSV showed the high stability in the source signature over the entire survey period, which is favorable for the use in time-lapse surveys. We also confirmed that the surface multiples could be suppressed in the processing we have introduced to exploit the utilization of multichannel signal processing to improve the SNR of acquired data. Moreover, we noticed that the surface multiples removed in the processing may also be used as signal to be superimposed with the processing data to enhance further the SNR.

Since the MSV does not sacrifice the power of signal generation against the towing depth and generated signal has high repeatability, the combination of deeply-towed MSV and our processing method could realize precise time-lapse survey which keeps the quality of survey data without large-volume amplitude.
Analysis of Offshore Dual Derrick Motion: The Impact of Accurate Modelling
Authors: Dandash Alaa , Xiao WenSheng , Liao HuaLin
Published: November 2020

The increase in demand for oil leads the petroleum industry to require more complex tools to increase production at lower prices. This complexity is reflected in the complex geometry, manufacturing, assembling, deformations, stresses, and loads acting upon the drilling tools. This paper considers the case of a dual derrick that is used in deep water conditions to reduce the time consumed during drilling operations. The derrick is in motion conditions under waves and current influence. This paper, introduces a novel methodology to simulate a dual derrick in a marine environment, where the procedure considers the derrick under compression, by means of the forces coming from drilling loads or any other vertical loads on one hand, and the loads coming from wave and current loads transferred by the platform on the other hand; i.e., putting the whole structure in equilibrium, and then imitate or simulate the derrick movement coming from wave and current effect, where the effect of this motion due to loads acting upon the derrick is the main concern of this paper. The calculations were performed in STATIC STRUCTURAL considering rotational velocity and rotational acceleration, while a separate evaluation was performed in TRANSIENT STRUCTURAL considering the influence of translation velocity in addition to the rotational velocity and rotational acceleration. The results showed that the vibration and translation of the derrick (platform), excited by waves and current, increased the stress induced by vertical loads considerably. The maximum combined stress induced in the derrick increased by 24 % because of the platform rotation, while the maximum bending stress increased by 30 % compared with the case where vertical translation was neglected and reached considerably high values in the water table and beams connected to the water table. Rather than utilizing the traditional method of using the transient analysis to employ forces changing (in direction and magnitude) with time, this paper used ANSYS WORKBENCH to simulate the movement of the structure, to watch the stress distribution that resulted from this movement.
Performance of Jack Up Rig Leg Penetration Prediction using PRSM for Offshore Malaysia
Authors: Nasri Huang Noorizal , Girsang Christian Hariady , A. Rahman Azam , Rohani Muhammad Joehan , Yusoff Norhayati
Published: November 2020

Regional Suitability Mapping (PRSM) was initiated in 2013 with the aim of optimizing operational cost efficiency, minimizing potential incidents during jack-up emplacement and assist in planning for rig selection. This paper will highlight the performance of jack up rig leg penetration prediction using PRSM for Offshore Malaysia.

PRSM comprises data analysis and integration from various sources such as geotechnical and geophysical site investigation data and data from rig entries. These data sets are then uploaded to a web-based Geographic Information System (GIS). The jack up rig leg penetration range predicted from PRSM GIS database is then compared to the actual jack up rig leg penetration. A comparison to the calculated jack up rig leg penetration was also made and the differences between these results are postulated.

A total of 23 recent jack up entry sites has been chosen randomly, which comprises 8 locations in Offshore Peninsular Malaysia, 12 locations in Offshore Sarawak and 3 locations in Offshore Sabah. The expected leg penetration at these locations were acquired from PRSM GIS. Results show that 75.0% of the sites in Offshore Peninsular correlate with the prediction range from PRSM GIS while only 27.3% of the sites in Offshore Sarawak correlate with the prediction range. For Offshore Sabah, all the locations correlate with the prediction range obtained from PRSM GIS. Results from predicted spudcan penetration calculated based on ISO 19905-1 (2016) against the actual penetration results show that 87.5% of the sites in Offshore Peninsular falls in between the ±10% reference band while 63.6% of the sites in Offshore Sarawak falls in between the ±10% reference band. However, none of the sites in Offshore Sabah falls in between the ±10% reference band. Findings from this exercise indicates area in Offshore Sarawak consist of two different features. Firstly, there are locations with thick sand layer close to seabed associated with shallow penetration of spudcans. Secondly, locations with presence of homogeneous clays with linearly increasing strength associated with deeper penetration of spudcans. Moreover, the available data around Offshore Sarawak field are scattered between one another, which leads to bigger data gaps. The shallow leg penetrations in Offshore Sabah are associated with the presence of coral and/or sand close to seabed.

This paper aims to showcase the use of big data and GIS to help in jack up leg penetration predictions hence optimizing the operational cost efficiency, minimizing potential incidents during jack-up emplacement.
The Relationship Between Axial Stiffness and Inner Core's Compressibility for Dynamic Cable
Authors: Chen Kai , Chen Kailang , Feng Ru'nan , Shi Luhao , Yu Guojun , Huang Yun , Lang Chunli
Published: November 2020

The theoretical calculated axial stiffness values of helical stranded structures which contain a soft inner core always result in a deviation from the test result, such as axial stiffness of dynamic cables. The deviation is normally caused by the compressibility of inner core. To compute the axial stiffness of a dynamic cable, it is necessary to get a way to evaluate core radial contraction, then to confirm the relationship between core compressibility properties and axial stiffness reduction. Fortunately, KNAPP's formula has already given a method to calculate the axial stiffness of helical strand structures which contain a compressible core and a soft inner core. However, some key input parameters still need to be carefully defined, which will significantly affect the calculation result.

This paper gives methods to define the input parameters. FEA and experiment are used to compare these four methods in order to obtain axial stiffness values estimates. The first method that taking the softest of inner core material as the dominant factor is regarded as the optimal one.
Field Cases Showing Little to No Impact of Reservoir Depletion on the Mud Weight Window
Authors: Salehabadi Manoochehr , Cid Alfaro Marcela , Tarang Ravie-Tajit , Zaini Mazlan , Leegte Henk
Published: November 2020

The fracture pressure in the reservoir is a function of reservoir pressure. Reservoir depletion will reduce the magnitude of reservoir pressure and consequently the reservoir fracture pressure. The fracture pressure changes because of reservoir depletion can lead to challenges like closure of mud weight window. Hence, the ability of predicting the fracture pressure changes due to reservoir depletion is a key for field development including infill drilling campaign.

A reasonable amount of field data has been published across the oil and gas industry to understand fracture pressure reduction as a function of reservoir depletion. The data show approximately a linear relationship between the reduction of fracture pressure with reducing reservoir pressure. Several studies and laboratory measurements have also been made to assess the impact of the reservoir depletion on the fracture pressure. Almost all the studies and laboratory measurements show reduction of fracture pressure as a function of reservoir depletion.

In this study, we present several field examples showing that severe reservoir depletion has little to no impact on the fracture pressure and consequently on the mud weight window. The examples show that heavily depleted reservoirs were drilled with high over balanced mud weight without seeing any sign of loss events. These observations are not fully aligned with what has been observed in the published field data.
Application of Thermo-Gel Treatment Assisting Multiple Thermal Fluid Huff and Puff for Enhancing Offshore Heavy Oil Recovery
Authors: Wu Jintao , Zhang Lei , Huang Jianting , Li Hao , Li Hongyuan
Published: November 2020

Multiple thermal fluid huff and puff, which uses nitrogen, carbon dioxide and hot water as thermal medium, has achieved a high increase of oil production rate in BN reservoir, a heavy oilfield locating at Bohai Bay. Six wells have completed two cycles of thermal huff and puff. Comparing to initial conventional production using natural energy, the periodic well production in first cycle increased to 1.6 times and the annual production rate of the whole reservoir increased from 0.4% to 0.7%. However, due to high formation oil viscosity (413∼741mPa•s) and strong heterogeneity, the injected fluid breakthrough happened three times in the second cycle. On one hand, the well production rate didn't gain an obvious increase because of the heat loss, on the other hand, the surrounding wells which were broken into had to be shut down. Consequently, the annual reservoir production rate was only 0.5%, which was much lower than project design. There is an urgent need to find a suitable solution to the injected thermal fluid breakthrough.

The most effective way to restrain the fluid breakthrough is injecting the thermal fluid into all the thermal recovery wells simultaneously, which is not realizable due to the offshore platform space limit. Combinatorial method with thermo-gel treatment have been optimized for more cycles of thermal huff-puff. Thermo-gel polymer and cross-linking agent spontaneously gel when they reach a critical temperature, which is configured between original reservoir temperature and reservoir temperature during thermal huff period. Thermo-gel was injected ahead and entered the high permeability channels mainly. With the plugging effects, the fluid breakthrough was prevented. Meanwhile, the thermal fluid permeated into low permeability zone where remaining oil concentrated, resulting to higher efficiency of injected heat.

Thermo-gel treatment was carried out for the rest three wells in the second cycle. Around each of the three thermal injection wells, there were 2∼3 wells that could have fluid breakthrough and only one surrounding well happened. Compared with the first three wells in the second cycle, the periodic oil increment of the last three wells increased to 2.6 times and the average effective period extended 105 days. Field practice showed a positive synergistic effect between thermal huff-puff and thermo-gel treatment. In the help of thermo-gel treatment, incremental oil production for single well has reached 1.58×104m3 in the past few years.

Our experiences show that such thermo-gel treatment assisting technology for thermal recovery is effective for enhancing oil recovery of heavy oil fields and meets the demand of high speed development for offshore oil fields.
Mechanism Investigation and Optimization of Conformance Control by Polymer Microsphere in Heterogeneous Offshore Oil Fields
Authors: Chen Xin , Li Yiqiang , Liu Zheyu , Zhang Jian , Li Xianjie , Zhang Han
Published: November 2020

As a good deep profile control and displacement agent, polymer microspheres have broad application prospects in oil fields. Three kinds of microspheres (MG-1 to MG-3) with different particle sizes are synthesized and evaluated. The microspheres observed by SEM are regular spheres with initial particle sizes of 3μm, 6μm, and 10μm, respectively, and the swelling ratios are between 2 and 4. The matching relationship between microspheres and pore throat is established and the optimum matching factor is determined based on the long core migration experiment. The optimal matching factors of the microspheres obtained by the plugging strength are respectively 1-1.2 to MG-1 and 0.5-0.8 to MG-2. In the range of the best matching factors, the effect of injection parameters on microsphere plugging effect and profile improvement capacity is obtained by a long core migration experiment. The results show that the concentration of microspheres mainly affects the timing of their injected into the cores. The increase in concentration and injection speed will decrease the injection performance of microspheres. The concentration and injection velocity of microspheres do not affect the deep migration of microspheres in the core. Microspheres have better profile improvement and EOR effect, and the permeability ratio has less influence on them. Finally, the mechanism of microspheres with different particle sizes on profile control and displacement is studied by the microfluidic model. The results revealed that the plugging mechanism of microspheres are single microsphere direct plugging and bridging plugging with different particle size.
Drill String Connection Backoff: Phenomenon, Fact or Fiction?
Authors: Plessis Guillaume , Morgan Dan , Hussain Raza , Goodwin Robert
Published: November 2020

Drilling practices continue evolving with a global quest for efficiency and an increased focus on the lower total cost of ownership. This leads to equipment/electronic upgrades on rigs and the use of new methodologies or tools in oil and gas well drilling. These have a potential to induce substantially higher loads throughout the string, which can remain invisible to the driller but have consequences on the drill stem product connections. As an original equipment manufacturer (OEM), we have noticed an increase in the number of queries related to connection backoff in the well. We would like to take this educational opportunity to share with the industry, especially younger generations, the most common root causes of loosening and/or backing off a connection down hole and ways to address them.

Over decades we have gained experience when dealing with our customers/users who have experienced connection loosening or backing off. We saw that every connection technology, from the API rotary shouldered connection to the premium ultra-high torque connections, could be exposed. Through investigations, rig visits, analysis, and adjustments made to the drilling practice, we have helped numerous players address this effect on land and offshore. As a result, we have identified several causes that can lead to these incidents.

Sometimes, basic physical principals can be overlooked. Often, dynamic phenomenon downhole is not captured, thoroughly understood, or ignored until they impose themselves. Finally, the running practice and connection torque management on surface can often be improved. With a minimum of preliminary planning at the time of well design, by embracing best industry practices on the rig floor and by monitoring what is happening, one can greatly reduce the chances of experiencing downhole back-offs and/or be in a position of making better decisions when they occur. This paper discusses, in detail, the likely root causes and offers ways to address these. While it will not completely eliminate the risks, our experiences and related investigations indicate that it will reduce the effect.
Effect of Crude Oil on CO2–Foam Stability
Authors: AlYousef Zuhair , Gizzatov Ayrat , AlMatouq Hana , Jian Guoqing
Published: November 2020

The use of foams is a promising technique to overcome gas mobility challenges in petroleum reservoirs. Foam reduces the gas mobility by increasing the gas apparent viscosity and reducing its relative permeability. A major challenge facing foam application in reservoirs is its long-term stability. Foam effectiveness and stability depends on a number of factors and will typically diminish over time due to degradation as well as the foam-rock-oil interactions. In this study, the effect of crude oil on CO2-foam stability and mobility will be addressed.

Two-phase flow emulsification test (oil-surfactant solutions) and dynamic foam tests (in the absence and presence of crude oil) were conducted to perform a comparative assessment for different surfactant solutions. A microfluidics device was used to evaluate the foam strength in the presence and absence of crude oil. The assessment was conducted using five surfactant formulations, and using different oil fractions. The role of foam quality (volume of gas/total volume) on foam stability was also addressed in this study. The mobility reduction factor (MRF) for CO2-foam was measured in the absence and presence of crude oil using high salinity water and at elevated temperatures.

The results indicated that foam stability has an inverse relationship with the amount of crude oil. Crude oil has a detrimental effect on foams, and foam stability decreased as the amount of crude oil was increased. There is good agreement between the results obtained from the two-phase emulsification test with those obtained from the dynamic foam tests in presence of crude oil. Depending on the surfactant type, the existence of crude oil in porous media, even at very low concentrations 5%, can significaly impact the foam stability and strength. The oil can act as an antifoaming agent; it enters into the thin aqueous films and destabilizes the film. This, ultimately, resulting in lower foam viscosity and less stable foams. Thus, the CO2 MRF dropped significantly with higher oil fractions.
Challenges and Practice of Key Technologies for Ultra-Deepwater Drilling with Very Narrow Pressure Window in South China Sea
Authors: Xu Dongsheng , Yang Jin , Liu Hexing , Qu Ximo , Yang Furong , Chen Lei , Yu Chen , Zhu Guojing , Hao Mingxuan , Wang Ning , Cai Rao , Xia Xi
Published: November 2020

Qiongdongnan Basin has deep water and narrow pressure window in South China Sea. In the process of drilling, it is often accompanied by complicated conditions, such as gas invasion, well leakage and breath effect during drilling. Therefore, we have carried out long-term research and practice. According to SPP, dc index, drilling fluid displacement and density and so on, we established a real-time gas invasion early warning neural network model. We formed multi factor measures to prevent lost circulation during drilling. We have drilled more than 20 deep-water narrow pressure wells, and the success rate of drilling reached 100%.

Key words: Ultra-deepwater drilling; Narrow pressure window; Gas invasion; Well leakage; Breathing effect
Effect of Gravity Drainage Models on Production Efficiency of Naturally Fractured Reservoirs
Authors: Aljuboori Faisal Awad , Lee Jang Hyun , Elraies Khaled Abdalla , Stephen Karl Dunbar
Published: November 2020

The gravity drainage process is one of the essential recovery mechanisms in the naturally fractured reservoirs. The contribution of the process to the ultimate oil recovery is quite uncertain, and it highly depends on the mathematical models that used in representing the process besides matrix characteristics such as shape factor and matrix block dimensions in addition to the matrix permeability. The fluid exchange rate between the matrix and fractures is the main controlling factor on the oil recovery, as most of the oil reserve stored in the matrix. Therefore, appropriate gravity model selection supported by accurate matrix characterizations can enhance the simulation accuracy and to avoid an overestimation to the oil recovery.

In this work, an outcrop-based model was used to provide a realistic representation of the fracture network in a dual-porosity model. The constructed fracture model was employed to assess the impact of the gravity drainage mechanism. The investigation comprises several sensitivity scenarios and cases to evaluate the influence of both mathematical models and matrix properties using an intermediate resolution model with a single producer located the grid centre and a natural depletion scenario.

The simulation results indicated remarkable differences in the producer's performance and productivity. The variation in performance is purely mathematical and related only to the gravity drainage options. Furthermore, the sensitivity results highlighted the significant impact of the matrix characteristics on the fluid exchange between the matrix and fractures, hence oil recovery. Therefore, misunderstand the impact of the mathematical models, and the influence of the matrix properties could result in a compound error in predicting the reservoir performance and its recovery, hence making an inappropriate development decision.
Critical Elements in Delivering Expedited Upstream Field Development Project: Gated Phase Approach, Team Work, Synergy, Open Communication, Quick Data Analysis and Fast Decision Making
Authors: Moid Farrukh , Nutaifi Abdulrahman Mohammad
Published: November 2020

The upstream Field Development Plan (FDP) and project delivery requires gated approach, close team collaboration, and synergy among all disciplines for success. This paper discusses a thorough phase-gate process with five phases and four gates to develop gas fields. The five phases comprise of Scoping of Project, Building Business Case, Appraisal and Testing, Full Field Development, and Monitoring. Critical elements before embarking on a field development with limited available data, and initial data gathering requirements in successful field development are discussed in details. Added benefits from project management, open communication, synergy and quick data analysis and decision-making during planning and executing are also described.
Effect of Biobased Lipid Surfactant on the Rheology and Morphology Properties in Alkaline–Surfactant–Polymer and Crude Oil System
Authors: Borhan Noorazlenawati , Salleh Intan Khalida , Numin Mohd Sofi
Published: November 2020

Injection of chemicals in enhanced oil recovery (cEOR) such as alkaline (A), surfactant (S), and polymer (P) can increase the oil recovery by changing the properties of the injected fluid to make better interaction with oil in the reservoir. In this work, micellar fluid interactions were studied via microemulsion rheological behavior using naphthenic crude oil and stimulated brine contains ASP. The influence of water cut (WC), temperature, salt concentration, shear, and viscoelastic properties were studied using a chemical cocktail consist of ASP and Naphthenic Acid (NAs) crude oil with a formulated biobased chemical that contained synthesized compound. The rheological properties, when added biobased formulation labeled as surfactant S53 and S57 in the ASP-crude oil system, resulted in a different viscosity — viscous-like behavior of emulsion and microemulsion in varying quantity of synthetic brine and temperature. At a specific volume of brine, both emulsion and microemulsion from S53 and S57 undergo a shear-thinning phenomenon where it behaves like a non-newtonian micellar fluid, as when viscosity decreases with the increase of shear rate. This thixotropy characteristic is suitable to be applied at the injection well in which high shear rate condition requires lower viscosity to assist in injectivity. The fluid when it flows into the reservoir, the viscosity increases sweep residual oil in pore and oil film in pore throats. Overall in this paper will describe the rheology and its microscopic behavior of emulsion and microemulsion generated on the addition of S53 and S57 surfactants in determining the condition of cEOR micellar fluids application.
Schizophyllan as Potential Environmental Friendly EOR Polymer for A Selected Malaysian Field
Authors: Ahmad Wazir Norhidayah , Abdul Manap Arif Azhan
Published: November 2020

This paper presents a comprehensive laboratory evaluation of Schizophyllan as an EOR polymer candidate for a selected peninsular Malaysia field. The polymer was chosen due to its well-known structure and properties. Schizophyllan, which originally produced from Schizophyllum commune was evaluated for its performance under controlled laboratory condition and the results are discussed accordingly. Rheology analysis at 96°C, showed that, at low concentration of 250ppm, Schizophyllan can achieve 11 cP which is about 90% more than live crude oil viscosity. Thermal Stability of this polymer was also excellent for the entire 3 months of exposure at reservoir temperature, whereby only 2.8% of viscosity degradation recorded with a very clear solution observed representing the heat and hardness resistance of the polymer. Injectivity test using actual native core indicated that, there was no plugging tendency or injectivity problem observed from the coreflooding test based on its low RRF value of 1.5. The resistance factor value of 9.93 indicates that this polymer is effective in viscosifying the water and injectable into the core. Dynamic adsorption study also showed that only 0.09mg/L of polymer was found adsorbed to the actual native core, despite the presence of clay in the core. Hence, from all the analysis, it was found that Schizophyllan meets the technical requirement to be applied as an EOR polymer