Slimhole Drilling Research Articles

An insightful multicriteria model for the selection of drilling technique for heat extraction from geothermal reservoirs using a fuzzy-rough approach

Geothermal energy stands out as an exceptional renewable resource for power generation, offering a consistent power production without the intermittency issues. Despite its potential to deliver a consistent supply of electricity on demand, geothermal adoption is hindered due to substantial costs. Utilising the most effective drilling method can alleviate this challenge by boosting efficiency and reducing operational costs. The primary goal of this study is to identify the best drilling method for extracting heat from geothermal reservoirs. This optimised approach facilitates better access to geothermal reservoirs, leading to increased heat recovery rates and improved project viability. Traditional methods often fall short in evaluating optimal drilling alternatives due to uncertainties. To address this, our research introduces an innovative paradigm that integrates novel T-Spherical Hesitant Fuzzy Rough (T−SHFR) set, method for the removal effects of criteria with a geometric mean and ranking alternatives with weights of criterion hybrid Multiple Criteria Decision-Making (MCDM) techniques. By leveraging the novel T−SHFR concept, our approach allows for a comprehensive assessment of various factors. This holistic evaluation ensures an exhaustive comprehension of the decision-making environment. The study reveals that reservoir characteristics play a significant role in selecting a sustainable drilling alternative. Furthermore, directional drilling appears as the most promising method with higher energy yields followed by slim hole drilling. The robustness and credibility of these findings are established through sensitivity and comparative analyses, indicating the potential applicability of this MCDM method to analogous challenges in different contexts. The findings of the ranking techniques were validated using Spearman's rank correlation coefficient, which revealed a positive and notable correlation. This research will empower stakeholders to make informed decisions, thereby enhancing the overall efficiency and sustainability of geothermal energy projects.

Advancing Slim-Hole Drilling Accuracy: A C-I-WOA-CNN Approach for Temperature-Compensated Pressure Measurements.

This paper presents a novel method to improve drill pressure measurement accuracy in slim-hole drilling within the petroleum industry, a sector often plagued by extreme conditions that compromise data integrity. We introduce a temperature compensation model based on a Chaotic-Initiated Adaptive Whale Optimization Algorithm (C-I-WOA) for optimizing Convolutional Neural Networks (CNNs), dubbed the C-I-WOA-CNN model. This approach enhances the Whale Optimization Algorithm (WOA) initialization through chaotic mapping, boosts the population diversity, and features an adaptive weight recalibration mechanism for an improved global search and local optimization. Our results reveal that the C-I-WOA-CNN model significantly outperforms traditional CNNs in its convergence speed, global searching, and local exploitation capabilities, reducing the average absolute percentage error in pressure parameter predictions from 1.9089% to 0.86504%, thereby providing a dependable solution for correcting temperature-induced measurement errors in downhole settings.

Research on slim-hole drilling technology for shale gas geological survey in China

Over the last 10 years, the China Geological Survey has deployed 137 slim-hole shale gas geological exploration wells for coring entire wellbores. These wells are primarily located in new blocks and geological formations where neighboring well data are insufficient, beyond the scope of developed oil fields in China, or outside of oil and gas company mining-right areas. The drilling rig equipment, coring tools, and core drill bits of slim-hole shale gas drilling technology are different from those associated with traditional petroleum drilling. Many studies have been conducted on non-coring slim-hole drilling technology. This paper focuses on coring technology and drilling safety, summarizing a set of high-efficiency shale gas drilling equipment and technology systems based on geological drilling equipment and techniques (that can be used for solid mineral exploration). We report on: 1) an improved vertical shaft drilling rig adapted to shale gas well control safety; 2) high-efficiency core drilling techniques, focusing on coring tools, and techniques incorporating an inverted tower drilling tool combination, air circulation follow-through technology, and expanded casing technology; 3) research progress on high-efficiency core drill bits, including non-planar tooth polycrystalline diamond compact bits and impregnated diamond core bits, along with their application effects. This research provides substantial advances in drill-core technology and improvements in exploration efficiency. Moreover, it provides a reference frame for well structural design and selection of construction technology for shale gas exploration drilling projects.

Investigation of The Effect of Temperature and Contamination on Properties of Saturated Salt-Base mud

The most difficult challenge that can be encountered when drilling a salt section is the difficulty of controlling the change in drilling fluid properties. In addition, the challenging geological environment was encountered. , creep behavior, slim hole drilling in salt formation have a few traits: high soluble, wash out salt section (1). The treatment did by using drilling mud that inhibits changes and is resistant to contaminants. Sodium chloride and potassium chloride brine were used to create a new mud for discussing this research, following up on changes in the properties of the new mud, simulating the conditions of Salt section (12.25'' hole) in the Noor oil field. Moreover, In this investigation studied the effect of temperature and contaminants such as salt, shale and anhydrite on new mud properties (Rheological properties, Filtration, PH with Different concentrations of Kcl & Nacl. The results indicate that the dissolution of salt formation decreases with increasing KCl concentration up to 5% for saturating NaCl salt. This reduces the contaminant impact and increases the stability of mud characteristics.

Technology Focus: Bits and Bottomhole Assemblies (December 2022)

Drilling-efficiency improvements must guarantee consistent reductions in project cost. The industry continues to pursue this critical requirement through different approaches—rate of penetration (ROP) maximization or cycle-time improvement. Recent advancements in technology, drilling processes, and applications characterization have begun to crystallize the differences and implications of the two methods. Most importantly, these efforts also identify crucial requirements and considerations that must be resolved as the move toward drilling analytics and automation gathers momentum. Considerations and factors that influence project costs must be identified and analyzed from an operational perspective, instead of the usual mechanical evaluations that focus just on ROP. Recent advancements in technology development, field performance trends, and applications characterizations have established the effects and contributions of numerous other factors such as vibrations control, durability, borehole quality, directional challenges, downhole tool life, footage drilled, borehole verticality, and ROP on operational costs. The different factors have peculiar relationships with, and effects on, project costs and must not be analyzed in isolation. Consequently, solutions needed to address risks, failures, opportunities, and associated implications of these factors must be developed holistically. Actionable lookbacks and relational benchmarking that focuses on the “why” and “how” of events rather than the “what” are critical requirements of this process. This systematic and holistic approach promotes cycle-time improvement, with measurable positive effects on operational costs. The methodology ensures that problems are addressed at their source, while certifying relevance and functional compatibility of all drilling-system components. Drilling analytics and automation must improve performance, with clear objectives to further drive down operational costs. To achieve these goals, critical pillars that focus on the holistic-solution approach and fast learning principles must be built. This strategy will promote process efficiency, explainable results, performance consistency, and fast adaptability by project teams. The industry’s commitment to improve drilling efficiency and reduce operational costs is in full gear, yielding positive results, because of the new alignment and focus on cycle-time improvement. Holistic methodologies and solutions needed for this endeavor pose several questions that must be answered because clearer and complete pictures must be drawn for all challenges. Recommended additional reading at OnePetro: www.onepetro.org. SPE 204129 When Slick Is Not Smooth: Bottomhole Assembly Selection and Its Effect on Wellbore Quality by Marc Willerth, Helmerich and Payne, et al. SPE 207423 Novel Motor Adjusts Bend Setting Downhole, Addressing Today’s Directional Drilling Challenges by Rohan D’Souza, NOV, et al. SPE 208541 Optimizing Bottomhole Assembly Design Criteria To Improve Mechanical Performance in Slimhole Drilling Environment by Stephen Fleming, Halliburton, et al.

Casing design of the KY slim hole well in “X” Geothermal field

Geothermal exploration activities including exploration drilling are important stages in a geothermal project. The high uncertainty of the amount of reserves and costs incurred in geothermal projects is a reason for investors to be reluctant to invest at this stage. One alternative is to use slim hole drilling technology instead of using standard hole or big hole technology. Slim hole drilling technology has long been applied in Indonesia in 1993 but has not continued its application. In 2015, slim hole drilling technology began to be used again at the Ijen geothermal field, East Java. Therefore, it is necessary to review the slim hole drilling, especially the casing design and hoisting rig capacity. The purpose of this study is to design a casing for slim hole KY well drilling, namely determining the casing seat at each depth, calculating the thermal stress value which is considered in calculating burst, collapse, and tension pressures. In addition to the casing design, rig sizing calculations were carried out, especially hoisting rig capacity in field X using slim hole reflection well data in the Ijen area, East Java. The results obtained are the determination of the minimum casing setting depth for the production liner 1500 m grade L-80, production casing 680 m, grade L-80, surface casing 240 m grade K-55, and conductor casing 30 m grade K-55. the results of thermal stress analysis, the maximum temperature obtained in the production casing is 425.3ºF and the production liner is 426.67ºF.

Research on tooth wear of non-spherical single-cone bit in hard rock formation of deep well

Single-cone bit are an important tool for slim-hole drilling. In view of the problems of drilling with a spherical single-cone bit, a new non-spherical single-cone bit is designed that breaks rock by impacting and scraping. The field experiment test show that the tooth at the small end of the cone was severely worn, and the tooth at the large end of the cone was minimally worn. To determine the cause of the eccentric bit wear, the tooth breaking rock was simulated using the finite element method. The tooth load, the cutting trajectory shape of each tooth, and the contact time between the tooth and rock were analysed. The theoretical model of tooth wear calculation was derived and compared with experimental results. The results showed that the tooth load at the large end of the cone was greater than the tooth load at the small end of the cone, but the contact time at the small end of the cone was longer. The field test results showed that the No. 6 tooth wear was small, and No.1, No.4 and No.5 was smaller. The No.3 tooth was the most severely worn. The results from theoretical model were consistent with the field test results indicating that the tooth wear theory formula can predict tooth wear.

Design simulation and test of hydraulic control system of RFID reamer while drilling

With the gradual improvement of exploration and development in deep and ultra-deep Wells, the demand for slim-hole drilling is increasing day by day. However, both the phenomenon of neck constriction and drill-jamming accident occur from time to time in the drilling process, and the annulus clearance between borehole and casing is too small, which resulting in high slurry annulus pressure loss, low displacement efficiency and poor cementing quality. Therefore, a kind of RFID reamer while drilling has come into being, the reamer blades can be controlled to open and close with the aid of RFID tag recognition technology without increasing the drilling cost, so as to complete the reaming operation while drilling. Taking the hydraulic control system as the research object, the hydraulic circuit has been designed based on AMESim software in this paper, so has its dynamic performance simulation analysis been carried out, finally, the ground test has been completed, the results show that the hydraulic control system is capable of accurately identifying the RFID tag information to drive the reamer blades to open and close, the overall pressure loss of the tool is about 1.0 MPa as the blades opened completely, which meets the requirements of field test.

TORQUE AND DRAG MEASUREMENT: A COMPARISON BETWEEN CONVENTIONAL, SLIM HOLE AND CASING DRILLING METHODS IN A DEVIATED WELL

Different locations and field conditions require various drilling methods to produce oil and gas. Three major operational methods are identified to be slim holes, conventional and casing drilling. Despite many affecting parameters, torque and drag are two highlighted factors for the determination of the best drilling method. Torque and drag play a significant role in the feasibility of drilling and its final costs. In this study, the influence of the torque and drag are investigated for the determination of optimum drilling type in consideration of the same S-shape well trajectory for all cases. Consequently, slim hole drilling showed minimum torque and drag value which meant that this method can be a good choice. Furthermore, casing drilling displayed maximum torque and drag in this study resulting in high sensitivity to the high degree of deviation. On the other hand, due to the constant weight of casing while drilling, this method showed a smooth increasing trend in terms of drag force while slim hole and conventional drilling showed significant changes in different parts of well trajectory. The number of build and drop sections significantly affect the amount of torque loss, while up to 50% to 70% of torque loss was observed in the drop or build section.Keywords: torque, drag, directional drilling, slim hole, casing while drilling, well trajectory

Evaluation and optimization of water-salt based drilling fluids for slim-hole wells in one of Iranian central oil fields

Abstract Slim-hole drilling in oil and gas industry has been developed extensively in recent years. Drilling fluid, in addition to providing appropriate rheological properties should produce a low annular pressure loss (APL) gradient while drilling. During slim-hole drilling, drilling mud hydraulics is an important concern, because due to reduced annular clearance, pressure loss can occur in drill pipe and annulus considerably. In this research, water based drilling muds were selected for the experimental work due to its low price, simple preparation and easy access to the required water. The research includes development and testing of water-salt based fluids. In this study, sixty-five samples of fluids were analyzed for their rheological parameters, the were considered using three various case study gas field wellbore configurations 6 1/8, 5 7/8 and 4 1/8 inch for their calculate APL gradients. Each composition was evaluated by the Power-Law and Bingham Plastic models and results of both models were compared. Choose of optimum fluids is based on suitable rheological properties, minimum annular pressure losses and maximum fluid transport ratio. Also, the effect of high temperature (180°F) on frictional pressure losses was studied. For an optimal formulation at high temperature from a well with distinct configuration 6 1/8 inch had an APL gradient of 0.149 psi/ft compared to 0.176 psi/ft at atmospheric condition. It was found that effect of high temperature on drilling fluids behavior is affirmative. On the other hand, the observed effect of high temperature on Power-Law fluids greater than Bingham Plastic fluids. Fluids with xanthan, in spite of high cutting carrying capacity and due to high viscosity have exhibited high frictional pressure loss. However, for some fluids, the annular pressure loss increased at high temperature due to green starch fermentation.

ОПЫТ РАЗРАБОТКИ МЕСТОРОЖДЕНИЙ ПЕРМСКОГО КРАЯ ГОРИЗОНТАЛЬНЫМИ СКВАЖИНАМИ

Hydrocarbon reservoir engineering has a top priority to achieve the highest possible value of the cost-effective oilrecovery factor. Structural deterioration of residual oil reserves and inevitable development of hard-to-recover reservesrequire new effective technologies and engineering solutions. Today, there is a tendency to replace the standard sizewell drilling technologies (including vertical, directional, horizontal, multilateral wells) and standard size dualcompletion equipment usage by slim-hole drilling technologies. In Perm Krai fields, more than 385 horizontal wellshave been drilled, while 3.4 % of them, i.e. 13 wells, have a small diameter. The conducted well operation analysisshows that the effectiveness of the horizontal well operations in a number of instances is significantly lower than thepotential one. This leads to a deteriorated economic performance of reservoir developments, and, eventually, to assetvalue reductions. Perhaps, the main reason of low effectiveness of the horizontal well operations lies is an insufficientunderstanding of geological and physical conditions of their successful operations. It has become obvious that drillinghorizontal wells in reservoirs with high compartmentalization, low net oil thickness, and decreased hydrodynamicconnectivity to the edge water zone offer a low level of performance. Productivity tends to decrease to average outputvalues of directional wells. Therefore, the problem of choosing a well design and its direction in specific geological andphysical conditions is highly relevant.

On the rock-breaking mechanism of plasma channel drilling technology

Plasma channel drilling (PCD), which is also known as high-voltage electric pulse drilling, is a highly efficient rock-breaking drilling technology with great development potential. This paper presents a method to study the rock-breaking mechanism of PCD technology. Then based on the predecessor's foundation, the factors affecting the development of plasma channels are explored using the dielectric breakdown model (DBM). Finally, a numerical rock-breaking model considering electric-thermal-mechanical three fields is established. This paper reveals the basic rock-breaking process of PCD and how the formation pressure affects the rock-breaking process of PCD technology. The main conclusions are: the formation law of plasma channel is related to the electrode structure and the inputting electrical parameters, the electrical properties of the rock and the type of rock; the plasma channel has an internal dynamic effect on the rock breaking process, and this internal dynamic effect of the plasma channel is sharply weakened after the channel is formed; shear cracks play a lead role in PCD, and the number of shear cracks is larger than that of conventional mechanical-rotary drilling; the formation pressure has little effect on the rock failure, the total volume of the chips, and the total number of cracks in the PCD, and the rock-breaking efficiency is not limited by the drilling depth. Finally, in order to improve the rock breaking-efficiency, it is recommended that the PCD technology be used in conjunction with slim hole drilling technology or jet drilling technology.

Indonesia’s Geothermal Resource Paradox: Unbundling Risks, Unleashing Private Capital

The belief that resource abundance equates to energy security is roundly debunked in Indonesian geothermal. Indonesia’s copious geothermal reserves remain untapped. Experts cite the usual culprits: unreliable long-term contracts, ambivalent government support, and lukewarm investors investment appetite. In this paper, we argue that the real constraints lie in investors’ unresolved contradictions: Quick to complain about government’s unreliable and shifting stance, investors look to the same counter-party to guarantee their “iron-clad power purchase agreements (PPAs)” to secure their returns. To unleash Indonesia’s geothermal potential, we propose adopting slim-hole drilling technologies to reduce costs, while facilitating sequential commitments. This could enhance strategic flexibility that lowers the costs of good failures while facilitating the adoption of resource insurance to de-risk geothermal exploration and drilling. To sustain these benefits, “cheap” energy policy needs to be phased out to allow a restructured PT Perusahaan Listrik Negara’s (PLN) to flourish by embracing commercially viable strategic approaches.

The viability of slim-hole drilling onshore Trinidad

Slim-hole drilling refers to the drilling of a well with a wellbore typically less than 7 in. in diameter. Slim-hole drilling is beneficial to the low-budget operator as there are considerable savings on rig time and costs and the rig size is ideal for drilling in remote areas. During slim-hole drilling, drilling fluid hydraulics is of great concern since significant pressure losses can occur in the drill pipe and annulus due to the reduced annular clearances. In addition, the flow regime generated in a slim-hole and the compatibility of the drilling fluid with the formation can have an impact on the stability of the wellbore. Slim-hole drilling has been successfully conducted onshore Trinidad in the Morne Diablo/Quinam Block for a number of years. The most commonly used drilling fluid is saltwater-based mud since it is cheaper and easier to dispose of than oil-based mud. However, the open literature did not show any studies conducted to determine the impact of drilling fluid hydraulics and drilling fluid compatibility on well-bore stability. In this study, 25 water-based drilling mud formulations were prepared using different concentrations of sodium chloride, potassium chloride and calcium chloride. The rheological properties of each formulation were determined and the Bingham plastic and power law models were applied. The frictional pressure losses for three commonly drilled slim-hole configurations were then computed and compared. Outcrop shale samples from the area were then treated with each formulation and the percentage loss in mass due to hydration and disintegration was measured for each sample. The results from these two tests showed that of the mud formulations tested, overall, those with KCl (2.9%) and CaCl2 (0.7%), KCl (3.6%), KCl (0.7%) and NaCl (2.9%), NaCl (0.7%), and CaCl2 (2.9%) were determined as best suitable for slim-hole drilling for the well configurations used. For these mud formulations, frictional pressure losses using both rheological models were the lowest and provide adequate rheological properties. The outcrop samples also showed the lowest percentage loss by mass when treated with these formulations indicating that they possess the desired well-bore inhibition properties. However, formulations containing NaCl only are the least expensive with straight KCl formulations being the most expensive.

Slim hole drilling and testing strategies

The financial and geologic advantages of drilling slim holes instead of large production wells in the early stages of geothermal reservoir assessment has been understood for many years. However, the practice has not been fully embraced by geothermal developers. We believe that the reason for this is that there is a poor understanding of testing and reservoir analysis that can be conducted in slim holes. In addition to reservoir engineering information, coring through the cap rock and into the reservoir provides important data for designing subsequent production well drilling and completion. Core drilling requires significantly less mud volume than conventional rotary drilling, and it is typically not necessary to cure lost circulation zones (LCZ). LCZs should be tested by either production or injection methods as they are encountered. The testing methodologies are similar to those conducted on large-diameter wells; although produced and/or injected fluid volumes are much less. Pressure, temperature and spinner (PTS) surveys in slim holes under static conditions can used to characterize temperature and pressure distribution in the geothermal reservoir. In many cases it is possible to discharge slim holes and obtain fluid samples to delineate the geochemical properties of the reservoir fluid. Also in the latter case, drawdown and buildup data obtained using a downhole pressure tool can be employed to determine formation transmissivity and well properties. Even if it proves difficult to discharge a slim hole, an injection test can be performed to obtain formation transmissivity. Given the discharge (or injection) data from a slimhole, discharge properties of a large-diameter well can be inferred using wellbore modeling. Finally, slim hole data (pressure, temperature, transmissivity, fluid properties) together with reservoir simulation can help predict the ability of the geothermal reservoir to sustain power production.

High-Performance Brine Viscosifiers for High Temperatures

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 183964, “High-Performance Brine Viscosifiers for High Temperatures,” by Peter J. Boul, Suhaib Abdulquddos, and Carl J. Thaemlitz, Saudi Aramco, prepared for the 2017 SPE Middle East Oil and Gas Show and Conference, Manama, Bahrain, 6–9 March. The paper has not been peer reviewed. Many viscosifiers currently used in high-density solids-free reservoir drilling fluids (RDFs) and completion fluids (CFs) are incompatible with high-density brines or require the use of prohibitively expensive brines to achieve target densities. There is substantial commercial benefit to developing a brine viscosifier with a higher temperature tolerance than is currently offered. A supramolecular viscosifier package has been developed that uses noncovalent associations between additives to enhance the thermal resilience of divalent brine fluids. Static aging-test data indicate that the supramolecular viscosifier outperforms high-performance, commercially available starch/xanthan brine viscosifier. Background The exploitation of oil and gas reservoirs found at increasing depths and the development of horizontal and slimhole drilling have increased the demand for high-density solids-free RDFs, CFs, and workover fluids (WFs). The use of divalent brine-based drilling fluids and CFs in well sections with temperatures exceeding 260°F is limited because of degradation of the polymers used to viscosify the fluid and suspend drill cuttings. Effective drilling fluids have numerous functions in well construction. They must have the physical properties required to carry cuttings from beneath the drill bit up the annulus of the well for separation at the surface. They must also provide cooling for the bit and be able to reduce-friction between the drillstring and the formation being drilled. This must be accomplished without damaging the formation. The inflow of fluids or solids from the drilling mud can cause formation damage, which can reduce the rate of penetration during drilling and can also decrease the rate of hydrocarbon production from a producing well. RDFs, CFs, and WFs must be density-adjusted to provide the hydrostatic head to preserve the integrity of the wellbore walls and to prevent blowouts. Although drilling through much of the well can be accomplished with oil- or water-based fluids weighted by solid particles of such minerals as barite, the reservoir sections offer a different challenge because of the concern that these solids could plug pores in the formation and reduce hydrocarbon-flow rates. It is for this reason that operators look to brines to provide density in RDFs. Recently, research in nanomaterials has revealed the potential of low-solids nanofluids for the prevention of formation damage.

Modeling of the Critical Deposition Velocity of Cuttings in an Inclined-Slimhole Annulus

SummaryA coupled computational-fluid-dynamics/discrete-element-method (CFD/DEM) theory is developed to simulate the transportation of cuttings in an inclined-slimhole annulus. In this theory, the liquid phase is governed by the Eulerian continuum equation and the Navier-Stokes momentum-conservation equation. The collisions between particle and wall, between particle and drillstring, and among particles are treated as the spring-damping system, and the particle-contact model is then established. The particle-governing equation based on Newton's second law is established by analyzing the forces on the particles. The CFD/DEM theory is developed by analyzing the forces on the dispersed particles per unit volume, which is the source term in the coupling. Using this CFD/DEM coupling algorithm, cuttings transportation in slimhole drilling is investigated, and the particle velocity and distributions are calculated. The calculated annular cuttings concentration is in good agreement with experimental data from the literature (Kim et al. 2014). The effects of the annular-fluid velocity, angle of inclination, cuttings concentration in feeding, and rotation speed of the drillstring on the annular cuttings concentration are also investigated. A correlation of critical deposition velocity has been proposed by use of dimensional analysis and nonlinear regression analysis. The correlation of annular cuttings concentration is also concluded. The new method proposed in this work is of great significance to hole-cleaning calculation and hydraulic-parameter design in slimhole drilling.

Drilling Waste Management and Control the Effects

Petroleum is among the world’s most important natural resources. The production of petroleum involves the generation of drilling waste which forms a major source of pollution in oil producing environment. Almost every process in the finding and production of petroleum generates many types of wastes which impacts the environment negatively such as the generation and disposal of cuttings and excess drilling fluids. These materials are discharged overboard in offshore operations or buried when drilling in land-based locations. As an effort to manage and reduce the impact of drilling waste on the environment there have been a number of techniques. Technologies such as directional drilling, slim-hole drilling, coil-tubing drilling and pneumatic drilling are few of the drilling practices that generates less amount of drilling waste. In this we discuss the environmentally responsible actions that require an understanding of the types of wastes and how they are generated and also a number of drilling waste managing technologies of minimising and eliminating the effect of drilling waste on environment.

Technology Focus: Well Integrity and Well Control

Technology Focus One of the more important aspects of well integrity during drilling operations is early kick detection. When an unintentional flow of the formation fluid into the wellbore occurs during conventional drilling operations, it must be detected promptly and the flow must be stopped, normally by closing the well. The early detection is crucial in minimizing the influx size. When the amount of formation fluid inside the well is large, especially if it is gas, the pressure inside the well will be higher during the subsequent well-control operations. This can lead to an increase in time to control the well or even to a worse situation: the loss of control. Another concern may be the amount of formation fluid to be handled at surface. Deepwater, high-pressure/high-temperature, and slimhole drilling are situations where early kick detection is mandatory. The early kick detection is accomplished with a rig equipped with the appropriate kick-detection sensors and alarms and with a rig crew trained in quickly recognizing a kick and in the shut-in procedures. However, there are situations where early kick detection becomes more problematic—for example, when operating on a floating rig because of its motions, when using non-aqueous drilling fluids because of gas solubility, or during connections. Recently, new technologies and research have been applied or developed to improve the kick-detection systems and to overcome some of the difficulties. To cite just a few examples, Development of automated kick-detection systems (one of the papers summarized here addresses kick detection during connections) Kick detection just above the bit using logging-while-drilling information Kick detection using wired drillstring Research on the effect on kick detection of gas solubility in nonaqueous drilling fluids (mineral oil, paraffin, ester, and olefins) The use of managed-pressure-drilling systems (one of the papers recommended for additional reading comments on the advantage of this technology in reducing the kick size) Recommended additional reading at OnePetro: www.onepetro.org. SPE/IADC 173153 A Barrier-Analysis Approach to Well-Control Techniques by D. Fraser, Argonne National Laboratory, et al. SPE 180047 Impact of New and Ultrahigh-Density Kill Fluids on Challenging Well-Kill Operations by T. Rinde, Acona Flow Technology, et al. SPE 180053 A Numerical Study of Gas-Kick Migration Velocities and Uncertainty by K.K. Fjelde, University of Stavanger, et al.

An Optimum Model for Slim Hole Well Kill

Abstract The slim hole drilling technology satisfies the oil and gas industry demands todays. As it offers not only a significant cost reduction but also minimize the environmental impact generated from the drilling operation. The cost reduction is realized from using smaller rigs and tubulars and less cement, drilling fluid and drilling cutting disposal1. In general slim hole wells reduce costs by 40-60% for remote exploration wells and 25-40% of development wells compared to the conventional wells2. The second main advantage of the slim hole drilling technology is the minimization of waste and improvement general environmental impact. If the size of the slim hole is half of a conventional one, the cuttings and mud volume will be 25% of a conventional volume2. Slim hole drilling technology has been impeded by the lack of documentation of well control methods for small annulus drilling3. One of the major barriers to the introduction of slim hole drilling technology to oil field operations was perceived to be the maintenance of safe standards of well control4. This paper will introduce a simple analysis of the pressures undergone by the well bore during killing operation so as to drive the optimum killing model for the slim hole wells.