The extraction of petroleum fluids from sub-surface accumulations mandates the drilling of a well into the formation containing the accumulation. The drilling techniques have evolved over time to overcome several challenges while some of the issues still prevail with the currently used drilling practices like loss circulation, large tripping time to change bottom hole assembly, stuck pipe problems and low well bore stability, to name a few. These decrease the drilling efficiency and increase the Non-Productive Time (NPT) of this highly capital-intensive industry encouraging the Petroleum Industry to look for new technology. Casing while Drilling (CwD) is a technique of drilling which has been proven to alleviate many of the problems faced while drilling. In this method, drilling and casing of a well bore is carried out simultaneously, which improves the drilling efficiency by reducing the NPT. It has proven to be beneficial in controlling loss circulation and improving wellbore stability by ‘Plastering’ effect, high quality cement job and increased rig floor safety. It uses smaller rig and less fuel thereby reducing carbon footprint in the environment. This paper studies comprehensive well control and casing string design consideration. Economics encourages its application that has been discussed in the paper. A case study on the application of CwD in Malay basin for top hole drilling is presented. Finally, the paper briefly outlines the technical challenges that need attention to get better results from CwD.

The Goldwyer Formation of the Canning Basin has been regarded as a highly prospective shale play. This study assesses the potential prospectivity of this source rock as an unconventional hydrocarbon resource. Considering the sparsity of wells penetrating the Middle Ordovician Goldwyer across the vast under-explored area of the Canning Basin, a basin-wide study of the source rock is not warranted. Goldwyer assessment of the Barbwire Terrace, a subdivision of the Canning Basin, is carried out instead.

This assessment includes the estimation of key shale play properties, such as, total organic carbon, total porosity, water saturation, and brittleness index. Each property was estimated from available well data by testing multiple estimation methods. TOC values were derived from multiple regressions of different well data. A simplified Archie's equation was used to estimate water saturation. Density porosity method was primarily used for total porosity estimations. Sonic data along with density were utilized to estimate brittleness index.

Each property was then modelled across the Goldwyer Formation within the terrace. This provided geostatistical estimates on the propagation of such properties. In order to generate sweet spot maps for the Barbwire Terrace, averaged maps of different properties were combined in a weighted manner. This approach attempts to simplify the complexity of unconventional resource assessment, which therefore has provided a single product evaluating the prospectivity of the Goldwyer as a hydrocarbon resource.

Results have shown that TOC and porosity are mostly the deciding factors for the prospectivity of this source rock, given that their values can be too small where the Goldwyer is deemed non-prospective. Nonetheless, sweet-spot maps show that most prospective zone is the Upper Goldwyer (Goldwyer I), followed by the upper parts of the Lower Goldwyer (Goldwyer III). More specifically, southern flanks of north-western and middle regions of the Barbwire Terrace tend to be more prospective. A stricter approach where cut-off values were applied for each property showed that sweet-spot maps are only prospective in the southern flanks of the middle Barbwire Terrace of Goldwyer I.

Water flooding type-curves, recently receiving increasing attentions, play an essential role in evaluation of OOIP and prediction of future production. The study proposed a method modified form Weibull model and water flooding type-curves to analyze the reservoir production performance, including predication of oil production and water injection rates. The results indicate that the method can estimate and provide solutions for oil production, water injection rate and injection-production ratio with a well accuracy. A case study is conducted to demonstrate the applicability and accuracy of model by field data. The matching results illustrate a good accordance between calculated values and field data.

Accurate prediction of the flow rate of horizontal gas well is necessary for economic feasibility, planning and development of gas field. Most of the early models assumed that the production from the horizontal well is infinitely conductive except few recent models. Some recent models reported in the literature for estimating flow rate in horizontal well where the pressure losses due to friction along horizontal drain hole was considered.

An improved model that checks the impact of all possible well bore pressure losses on gas production rate of horizontal well is reported. The neglected impact of well bore pressure losses due to fluid accumulation and kinetic energy in the past models is thought to be a conceivable reason for the inconsistency between computed rates from the models and rates got from production tests. The new model was validated using the same field contextual investigation utilized by Guo et al. and outcome got from the new model yields more satisfactory results. A more realistic results that evident all flow phenomena in gas well include the initial unsteady, pseudo-steady and steady state flow condition hence flow rate at any given production time has been established for flow of gas along horizontal well. The outcomes of the study demonstrate that the percentage deviation of the new model at steady state flow condition is less than 5.0% compared with 11.05% acquired from Guo et al. model following by 259.7% from Furui's model, and 1118.2% got from Joshi's model. This work gives field operators a precise and helpful device for prediction and assessment of production in a gas horizontal well.

Ultrasound is an unconventional method used to recovery oil, despite the report on the use of this technique, the focus has always been on the continuous application of ultrasound. But the continuous ultrasound has its own limitation of high cost of production and maintenance of equipment because of high energy generated. In this study, the use of short duration, intermittent ultrasound was investigated, and the result compared with the continuous ultrasound. The effect of viscosity and intensity on both intermittent and continuous ultrasound was also investigated. A 2D micro-model placed inside an ultrasonic bath under an ultrasound radiation was used, a stereo microscope with the camera mounted at the top of the micro-model recorded the displacement process. The snapshot of each time interval was used to give the estimate in percentage (%) of the residual oil left in the micro-model. The results show that, short duration and intermittent ultrasound can recover more oil compared with the application using continuous ultrasound and longer duration. Therefore, the use of intermittent ultrasound as a green and cost-effective technique is herein proposed.

It is an important mechanical parameter for fracture toughness that affects hydraulic fracturing. Some methods such as indoor test core and logging data interpretation are commonly used to obtain fracture toughness. These methods, however, have their own limitations. Liu's method has focused the mechanical properties of shale including fracture toughness based on micro-/nano-indentation experiments. Zeng's method has pointed that the former method of calculating fracture toughness ignores the maximum holding stage in the indentation-displacement curves, they point out and correct the fracture stress intensity factor model, but the final calculation of the fracture toughness of the numerical difference is of two orders of magnitude. In this paper, micro-indentation experiments were carried out to further analyze and correct the model by collecting and analyzing Longmaxi shale cuttings. After Zeng and Liu's methods are combined, the irreversible elastic energy by energy area actually was measured. To some extent, the difference between the two kinds of fracture toughness is reduced.

Low salinity water is an emerging enhanced oil recovery (EOR) method that causes wettability alteration towards a favorable state to reduce residual oil saturation, while water alternating gas (WAG) is a proven EOR process that enhances oil recovery by controlling mobility of both water and gas. Therefore, combining the two EOR processes as low salinity water-alternating CO₂ EOR injection (LSWA CO₂) can further improve oil recovery by promoting the synergy of the mechanisms underlying these two methods.

Core flooding experiments, contact angle, interfacial tension (IFT), and CO₂ solubility measurement in oil and brine were conducted to investigate the viability and performance of LSWA CO₂ in sandstone reservoirs. A favorable wettability alteration, along with IFT reduction and mobility control, are the mechanisms that contribute to residual oil mobilization efficiencies during the LSWA CO₂ EOR process. In addition, LSWA CO₂ core flooding experiments result in a significant incremental oil recovery.

Three smart waters were tested in our research, to examine the impact of changing cationic composition on oil recovery. The solutions are designed brines as NaCl (SW1), MgCl₂ (SW2), and KCl (SW3). Of the three solutions, SW1 yields the highest incremental oil recovery and highest IFT reduction. In addition, it results in a favorable wettability alteration towards a more water-wet state.

In all cases, introducing CO₂ to the brine/oil system shows a great advantage in terms of enhancing wettability modification, promoting IFT reduction, and controlling the displacement front of the injected fluid through mobility control.

Mineral analysis plays a major role in the successful matrix acidizing as it shows the change in physiochemical changes in the formation due to the reaction with fluids injected. Mineralogy of the reservoir can be altered by injecting mineral acids during matrix acidizing. But various complications are connected during the application of these acids such as environmental hazards, corrosion of pipes and tubings, precipitation of fluosilicates and fast spending of acid. To mitigate these problems, chelating agents have been applied as an alternative by different researchers. In this study, three different chelating agents EDTA, GLDA and HEDTA were applied to stimulate sandstone and dolomite samples. The pH value of these chelates ranges from 1.7 to 3 and is measured before and after core flooding to observe physiochemical changes. Core flooding experiments under 180 °F temperature were performed at a constant flow rate of 1 ml/min on core samples having dimensions (3 inch × 1.5 inch). Porosity, permeability, Inductively Coupled Plasma (ICP), and TESCAN Integrated Mineral Analysis (TIMA) were employed to measure changes in formation properties such as morphology, topology and mineralogy. The reacted sample of acids was analyzed for sodium, potassium, calcium, aluminium, magnesium, and iron using the ICP technique to find the capability of these chelates to remove positive ions. HEDTA found to be effective in chelating iron, calcium and magnesium and it also removed some amount of aluminium ions from the sandstone samples. Permeability and porosity analysis concluded that HEDTA is more efficient in creating new big pore spaces. TIMA analysis confirms that HEDTA is effective in dissolving quartz and other positive ions while dissolved a large amount of calcium and sodium from the sandstone as compared to other chelates. TIMA analysis also concluded that HEDTA is effective in increasing porosity of sandstone formation while GLDA is effective in dolomites.

In this study, crude rice bran wax oil -in -water emulsion (named CRBWE) was prepared by agent-in-water method. The critical factors influencing the sample preparation process were optimized. For instance, the optimum hydrophile-lipophile balance value of compound emulsifier was 12.33-13.40, the content of compound emulsifier was 10 wt%, the emulsification temperature was 70 °C-80 °C, the agitation speed was 200 rpm, and the emulsification time was 30-45 min. The performances as a lubricant of drilling fluid were also evaluated with respect to lubricity, rheology and filtration loss of CRBWE. The results showed that CRBWE had good lubricity and didn't affect the rheological properties of drilling fluid. For example, when it was added into bentonite dispersion at room temperature with the fraction of 1 wt%, the coefficient of friction of bentonite dispersion dramatically decreased to 0.077, and the coefficient of friction reduced rate was greater than 80%. Overall, these findings indicated that CRBWE would have promising applications as environmental friendly lubricant of drilling fluids to reduce torque and drag in petroleum and natural gas drilling.

Fluid leak-off phenomenon plays a critical role in hydraulic fracturing operation. This phenomenon can be very impressive in successful operation of hydraulic fracturing. This operation is very complex in fractured reservoirs due to the reaction between induced fracture and natural fractures. In this study with the cohesive element method, the effect of presence of natural fracture on the magnitude of hydraulic fracturing fluid leak-off is investigated. First of all, cohesive element and extended finite element method methods are described. The fluid flow inside hydraulic fracture and the affecting parameters on leak-off of this fluid on adjacent environment are analyzed. Then, effects of natural fracture on hydraulic fracturing direction such as deviation, leak-off and the mutual influences (which includes the changes of stress regime around the natural fracture) and also changes in pore pressure are processed. The results indicate that presence of natural fracture will cause reduction in aperture of hydraulic fracture. This decrease will lead to extension of fluid lag and eventually delaying of leak-off phenomenon. However, this effect is negligible against the positive impact due to shear and normal displacement on increasing leak-off.

Raw gas gathered from well production has to be treated to extract its ethane, to remove carbon dioxide (CO₂) from it and to dry it, so that the send-out ethane gas complies with transport constraints and meets sales-gas specifications. Two distinct families of solvents are used generically for such gas treatment: chemical and physical solvents. The South Pars gas field development phases 9 and 10 feeds gas and natural gas liquids into a processing and fractionation plant (one of the largest gas processing plants in Iran), and is associated with concentrations of 5.37% mole CO₂ in the raw gas produced. Furthermore, there are potential problems associated with the CO₂ treatment, such as the high-energy requirements for amine solvent regeneration, corrosion caused by aqueous amine solvents and waste/losses (solubility, vaporization) of the solvent used to remove CO₂ in the ethane treatment unit.

A feasibility simulation study was conducted to evaluate the utilization of Sulfinol-M + AMP solvent (Sulfolane plus Methyl di-ethanol amine plus 2-amino-2-methyl-1-propanol (AMP) plus H₂O) to replace the aqueous amine solvent (DEA) currently used in the ethane treatment unit of South Pars phases 9 and 10 gas processing plant. The simulation of the Sulfinol-M + AMP process demonstrates less energy consumption (11241.242 kw versus 11290.398 kw for DEA), negligible corrosion and lower losses of solvent (376.493 kg/h versus 409.2421 kg/h) relative to alternative solvents considered, because of its low vapor pressure.

Double shoulder drill pipe joint (DSJ) is a novel thread structure which appears in recent years. Its strength reduced efficiently while the structure design is not appropriately, for the DSJ’s mechanical behaviors weren’t well studied. In this paper a 3D whole structure finite element model of DSJ was established based on the Principle of Virtual Work, and validated the model’s computing results by experimental results. The Authors analyzed the stress and strain distribution with the 3D whole structure finite element model’s computing results under torque moment, compression force, tension load, and bend moment. And then acquired the DSJ’s mechanical behaviors under each load. The research works of this paper refer accordance to recognize and design the DSJ.