Coiled Tubing Unit Research Articles

Hydraulic Radial Drilling Using a Rotary Hydraulic Nozzle Aimed at Increasing the Exploitation of Deposits

The exploration and development of new hydrocarbon deposits face increasing challenges, primarily driven by the shift away from hydrocarbons towards renewable energy sources like shallow geothermal deposits, wind farms, and photovoltaics. This shift necessitates finding solutions that minimize environmental impact and enable increased energy extraction from existing or decommissioned fields and wells. This paper explores the possibility of excavating from potentially depleted fields, where a significant portion (up to 85%) of the reservoir’s resources remain unrecoverable due to low reservoir energy. To address this, secondary and tertiary exploitation methods are proposed involving the supply of external energy to increase the pressure in the reservoir layer, thereby enhancing resource exploitation. One of the suggested tertiary methods involves reaming the deposit with multiple small-diameter radial holes using a hydraulic drilling nozzle. The entire process comprises several key components, including the coiled tubing unit (CTU), high-pressure flexible hose, window drilling kit for casing pipe, kit for positioning the exit of the hydraulic drilling head from the casing pipe, anchor, and hydraulic drilling head attached to the end of the high-pressure flexible hose. This method aims to increase the contact between the reservoir layer and the wellbore, potentially leading to an increase in or initiation of exploitation in certain deposit scenarios. The described method presents an environmentally friendly approach, eliminating the need for drilling new boreholes and offering cost-effective access to resources in decommissioned deposits with insufficient reservoir energy for self-exploitation. The applicability of this method to extract methane from coalbed seams is also mentioned in this article. In a separate article, the authors detail the design of a hydraulic drilling nozzle specifically for reaming the reservoir layer.

Robust Scale Dissolver Mitigates Mixed-Scale Issue in South China Sea

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211187, “Tackling Mixed-Scales Issue in an Oil Field Using a Novel Robust Scale Dissolver,” by Nora Aida Ramly, Luky Hendraningrat, SPE, and Latief Riyanto, SPE, Petronas, et al. The paper has not been peer reviewed. _ The evaluation of a recently developed robust solid dissolver (RSD), from the laboratory phase through pilot deployment, is presented in the complete paper. Based on laboratory tests, the RSD can dissolve mixed scales completely in 24 hours at well temperatures while experiencing no incompatibility issues with production chemicals and all pumping and wireline components. The RSD was developed based on the total organic system that can prevent corrosion and is compatible with hydrocarbon. The RSD was piloted at oil Well 1 in Field PN and successfully removed mixed scales, allowing the well’s revival. Introduction Solid scale deposition is one of the most frequent flow-assurance issues both in subsurface and at the surface. The scale can be classified as organic (wax or asphaltenes), inorganic (calcites, sulphates, sulfides, halites, carbonates, and oxides), soap-related (naphthenates and carboxylates), gas-related (hydrates), or mixed scales. Scale occurrence, quantity, and severity mainly are determined by mineralogy, water chemistry, reservoir pressure and temperature, and the flow characteristics of the producing fluid in the well. Furthermore, scale formation is exacerbated by higher pH conditions and a higher water-cut environment, as would be expected in oil fields where water is to be injected for pressure maintenance. The most common type of scales found in Malaysian oil fields are organic and inorganic scales. The operator’s previously deployed scale-dissolving chemical in its fields only could cater to a single type of scale treatment at a time, which was ineffective for dissolving mixed scales simultaneously. Another method is the use of a mechanical solution using a coiled tubing unit (CTU). Removal mechanically by CTU in tubulars is a successful method in removing hard barite scales, but the cost is high and the method requires several days of production deferment. An improved and cheaper mixed-scale removal approach was needed to clean out mixed-scale issues in more-challenging brownfields. The RSD technology was developed for wellbore cleanout caused by mixed scale based on a stable microemulsion solution consisting of acid and solvent components. The solution was proposed to dissolve both organic and inorganic scales simultaneously in the near-wellbore area and tubing string of an oil well. The very small droplet size formed by the surfactant system and solvent is a significant advantage of using microemulsion and can allow penetration even in tight formations with small pore throats and promotes more-uniform surface coverage because of the increased interfacial area of the droplets. Previous studies have reported that the microemulsion can be pumped without causing a significant increase in pumping pressure.

Economic And Sensitivity Analysis Stimulation Of Coiled Tubing And Bullhead Combination On A Horizontal Well

Production decreased often occur in Indonesia's oil and gas fields which becomes a problem for oil well exploration. Thus the role of the company demands to be able to re-optimize the flow rate of oil production in the oil and gas field. One of the workover jobs was stimulation. The function of the work was to stimulate the wells mechanically and chemically which aimed to increase the productivity of wells that have experienced a decrease in oil production, in which mechanical stimulation was in the form of coiled tubing units and bullhead used chemical stimulation, namely acidizing and solvent. To prove the economy of the coiled tubing unit and bullhead stimulation work, calculations and analysis of economic indicators such as net present value (NPV), internal rate of return (IRR), and payout time (POT) can be carried out. Where this study aimed to determine the economics of the stimulation project carried out on the horizontal wells of the RD field. The results of the calculation of economic indicators that will be feasible are not like this stimulated workover work project with an investment of US$ 133,053 acidizing coiled ribbing oil price of 68.51 USS/bbl thus the calculation of NPV @ 10% 60631 USS, POT 0.74 months, P1 9, is obtained. 73, IRR 355%, coiled tubing solvent well US$ 185,967.166 NPV@ 10% 98,431 USS, POT 3.94 months, PI 3.69, IRR 103%, bullhead acidizing well US$ 8858.31 value NPV@10% 218029 USS, POT 0.95 months, P1 45.16, IRR 1890% and bullhead solvent USS 72745 value NPV@10% USS 248586, POT 0.94 months, PT 52.53, IRR 1822%. Sensitivity analysis on stimulated workover work is carried out by changing the assumptions with 85% and 115% then the results obtained are the oil price value which is the parameter that most influences the NPV value then oil production, and capex. From the results of profit indicator calculations and sensitivity analysis, it can be concluded that the stimulated workover work in the RD field is all feasible because it meets the eligibility requirements of a project.

EXPERIMENTAL AND NUMERICAL RESEARCH IN THE FLEXIBLE PIPES OF COIL TUBING INSTALLATIONS TAKING INTO ACCOUNT THE RHEOLOGY OF THE TECHNOLOGICAL FLUID

The current direction of the country's economic development is an intensive increase in hydrocarbon production on the territory of Ukraine, the introduction of new modern technologies and an increase in the efficiency of power equipment. One of the modern directions used in the oil and gas industry is the use of specialized equipment for coiled tubing units. Also, with the development of well drilling and oil production intensification technologies, modern multicomponent flushing (process) waters appear. The need for polymers is based on their ability to influence the properties of aqueous and hydrocarbon systems and form gels of different density, viscosity and rheology. Polymer systems are widely used due to their high cleaning, transporting and holding properties. Widely known polymer systems of technological solutions based on Xanthan Gum. Generalized information about the rheological parameters of fluids used to intensify the work of oil and gas wells is considered. The main rheological indicators of the studied liquid are the shear stress and the strain rate of the medium. These indicators are determined using an OFITE 900 rotational viscometer. The results of experimental studies of the properties of an aqueous solution with different concentrations of Xanthan gum from 0.6 to 8 g/l are presented. The study showed that an aqueous solution of gum creates a non-Newtonian behavior of the liquid. The coefficients of the rheological model of the solution were obtained by approximation of laboratory data. To simulate the hydrodynamic characteristics of a polymer system, a nonlinear viscous fluid model and a model with the introduction of effective viscosity are used. The results of studies of rheology indicators are used to determine the fluid flow regime, predict the hydraulic resistance coefficients in pipes and the energy characteristics of pumping equipment for supplying process fluid to the well. Experimental and calculated dependences of the influence of polymer additives on the resistance to the movement of liquids in coiled tubing of a coiled tubing unit are presented. The analysis of experimental and numerous hydrodynamic studies has been carried out. For numerical simulation of the hydrodynamics of non-Newtonian behavior of fluid in pipes, the open integrated platform OpenFOAM is used.

A Fuzzy Inference System for Detection of Positive Displacement Motor (PDM) Stalls during Coiled Tubing Operations

Positive Displacement Motors (PDM) are extensively used in the oilfield, either in drilling or in coiled tubing (CT) operations. They provide a higher rate of penetration and the possibility of drilling horizontal wells. For coiled tubing operations, PDMs can mill through obstructions and enable shut-in wells to work again. One of the major challenges while using these tools is the motor stalling, which can lead to serious damage to the PDM and lost time events in drilling and workover rigs. These events result in total losses of hundreds of thousands of dollars, and their avoidance mostly depends on trained and fully aware equipment operators. If a PDM starts to stall, the pumping needs to be halted immediately or the tool may fail. This paper describes the use of a Fuzzy Inference System (FIS) to detect the stalling events as they start to happen using the acquisition data from the coiled tubing unit, the output of the FIS could then trigger an alarm for the operator to take the proper action or remotely stop the pump. The FIS was implemented in Python and tested with real CT milling acquisition data. When tested using real data, the system analyzed 68,458 acquisition points and detected 94% of the stalling events across this data during its first seconds, whereas, during the real job, a CT operator could take longer to notice this event and take the proper action, or even take no action. If the FIS was applied on a real coiled tubing acquisition system, it could reduce PDMs over-pressurization due to stalling, leading to an increase on its useful life and decrease on premature failure. As of now there is no similar system in the market or published and this kind of operation is fully performed using human supervision only.

Awi A-4 Comprehensive Well Evaluation for Successful Well Intervention Program

AWI A-4 well has the highest Non-Condensable Gas (NCG) content among other production wells in the Salak field with NCG content 10%-wt. NCG interference study indicated that AWI A-4 has the most substantial connection/interference to several surrounding high NCG wells. AWI A-4 encountered wellbore obstruction (scaling) in 2012, which increased the NCG content of surrounding wells and power plant Unit-4, causing generation loss. Another impact is steam supply reduction by 71.8 kg/s because of maintaining Unit-4 NCG content below its maximum Gas Removal System (GRS) capacity by 2%-wt. Wellbore scale clean out was conducted in 2015 but failed and even plugged the wellbore. A comprehensive evaluation of well AWI A-4 wellbore condition and well characterization was conducted involving a multidisciplinary team (Drilling, Reservoir, Production, Geochemistry) in order to obtain a better understanding of the main cause of well AWI A-4 wellbore plug then develop the proper method to clean the wellbore plug and improve wellbore accessibility. After evaluating well AWI A-4 wellbore condition comprehensively, a new scale clean out program was developed using rotojet Coiled Tubing Unit (CTU) in 2017 which was finally able to improve wellbore accessibility well AWI A-4 including NCG content reduction of surrounding high NCG wells and power plant Unit-4. This successful wellbore accessibility improvement has a positive impact on additional/incremental steam supply by 84.4 kg/s, including other steam supply projects delay and cancellation, so that reduce the company’s operational cost.

The Competitive Advantage Analysis of PT Halliburton Indonesia By Using Resource Based View

<p>This research is a descriptive quantitative research embodied in a case study of PT Halliburton Indonesia. This study is aimed to analyze the company competitive advantage with the resource-based approach, through the identification towards resources and capabilities that manifest the competitive advantage and sustainable competitive advantage for the company as well. The method for data collection was conducted through the data acquired from policy maker institutions in upstream oil and gas industry and the data from related research journals, as well as distributing questionnaires and interviews to 6 subject matter experts who are the associated officials of PT Halliburton Indonesia.</p><p>The research results show that there are 29 resources and 10 capabilities that influence the success of the company in the upstream oil and gas industry (strategic industry factors). Discussing in further, through the resources and capabilities appraising analysis, there are 16 resources and 8 capabilities identified as the key strengths of PT Halliburton Indonesia and become the competitive advantage for the company. Then through the VRIO test, 5 resources that become the sustainable competitive advantage for PT Halliburton Indonesia are identified. These resources are coiled tubing units, well-cementing units, packers and bridge plugs, subsurface safety valve equipment, and good corporate reputation towards clients.</p><p>This research provides an overview regarding the available resources that become the sustainable competitive advantage for PT Halliburton Indonesia. Therefore, its development, maintenance, and deployment become a priority for the company. The company needs to acts to exploit those potential tangible resources in an optimal manner through a series of continuous activities of research and technology development (R&D), in similar to the intangible resource, such as a good reputation towards the client. The company needs to maintain its good reputation through the standard fulfillment of quality service in various aspects.</p>

Customized Solutions for Coiled Tubing Interventions in the Bolivian Sub-Andean Basin

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202620, “A Review of 25 Coiled Tubing Well Interventions: Customized Solutions for Bolivian Sub-Andean Basin,” by Jovanny A. Hernandez, SPE, Luis F. Antelo, SPE, and Carlos D. Rodriguez, Halliburton, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Fields in the Bolivian Sub-Andean Basin are remote and difficult to access. The producing zones include the country’s most challenging wells, with depths of up to 26,000 ft, with high pressure/high temperature (HP/HT), high gas cut, crossflow, dogleg severity, and well-access restrictions. The complete paper reviews 25 coiled tubing rigless well interventions (CTRWI) to extend the life of those wells, including operations involving nitrogen (N2) lift, acid wash, milling, shifting sleeves, setting packers, stimulation, velocity strings (VS), and fishing. Introduction CTRWI in Sub-Andean Basin fields had not been implemented historically because of limited road access to the fields, lack of available equipment with high technical capabilities, high pressure, and well depth. Beginning in 2017, however, operators evaluated the risk and elected to perform CTRWI involving stimulation, cleanout, N2 lift, fishing, VS jobs, and other techniques. Equipment with specialized capabilities was requested to address the operational requirements and the ability to travel on the remote roads while respecting transit regulations limiting maximum weight to 55 tons. The challenges to transporting equipment economically include - Transportation of large reels of 2⅞-in. coiled tubing (CT) string to complete dual-sectioned VS installations - Transportation of CT unit with 6,600 m of 1¾-in. CT string (weight of less than 55 tons) - Continuously moving large volumes of N2 to the field Wells in these fields were drilled no more than 10 years ago. The majority were built with smart completions, several production layers separated with swell packers and flowing through sliding sleeves configured with the same direction of actuation for opening and closure. Completions are configured with production tubing sizes of 7, 5, 4½, and 3 in. The tubing and accessories are made from chrome 13 because of the presence of carbon dioxide in the production fluids. The region includes some exploratory fields having HP/HT conditions and mature fields with declining production. These wells are important for both the operators and the local government because their production represents more than 50% of national production. On-Site Laboratory Testing Characteristics of produced formation water and mineralogy tests of water samples helped identify a calcium carbonate (CaCO3) scale type. Because CaCO3 scale is known to be acid-soluble, a tailored acid-treatment system was selected with a static formation temperature between 220 to 286°F. On-site laboratory tests using a combination of 13% acetic and 9% formic retarded acid treatment systems were applied to the samples obtained, and results of a solubility test were observed. The selected treatment was demonstrated to be highly effective at dissolving CaCO3 scale according to the test made at the wellsite. High confidence was placed in the test results of the acid-treatment sample because dissolution was above 85% in a 4-hour test period under static well temperature.

Corrosion resistance of steel for coiled tubing units

The gravimetric method was used to determine the corrosion rate of a pipe for coiled tubing. Scanning electron and optical microscopy were used to study the microstructure and to determine the nature of corrosion damages. It has been found that corrosion processes of different nature occurred in the studied systems “metal – environment”, in particular, in acid solutions, corrosion was caused by the of hydrochloric acid and the ambient temperature of 70°С. In solution with a smaller acid content, along with the general corrosion, there is a significant localization of the corrosion process (deep corrosion damage is formed: macro pitting and corrosion ulcers). The general corrosion was observed in the HCl solution (13 mass %), which destroys the pipe walls after 576 h of exposure. The neutral solutions caused the general corrosion of smaller intensity in comparison with the acidic environments, even taking into account the temperature factor. The surface-active substances or petroleum products that are present in the solutions, form barrier films on the steel surface, which prevent the access of corrosive components from the environment to the surface of the material, especially during the short exposure time. With the increase of the exposure at the elevated temperatures, the barrier films break down and the steel surface undergoes the general corrosion.

Evaluasi Rigless Plug & Abandonment: Sebuah Studi Kasus

Oil was explored and found by Royal Dutch (Shell Group) geologist in early 1900. And since Indonesia’s independence, development in oil and gas projects was able to put Indonesia as one of major oil exporter country with daily production above 1 Million barrel per day in 1970 – 1990. With time as fields become mature, some of the fields have come to the end of its life cycle, where mostly 70% of Indonesia total old oil wells will have no economic value and has to be permanently Plug and Abandonment (P&A) as ruled by the government. It’s part of decommissioning an entire field with environmental preservation which called Abandonment and Site Restoration (ASR). As P&A will impact operating company investment as outlined in Ministry of Energy and Mineral Resources (ESDM) No. 15, 2008, efficient P&A operation should be evaluated to ensure proper planning and executions. The subject of evaluation is X well located onshore at Y Field, Java, Indonesia. P&A operation with multiple cements plugs as barriers to ensure no fluids migrations from one formation to others, or to surface. Evaluation between workover rig and rigless P&A operation with coiled tubing unit (CTU) and electric line (E-line) will be presented in this paper to value the expenditures and achieving the result as standardize by the government with accordance of operating company standard. Results show that rigless operation is the preferable solution, which lead to cost effective operation. Rigless operation saves 25% of P&A operations even tough with longer operation days.

Effect of pilot-scale UV-C light treatment assisted by mild heat on E. coli, L. plantarum and S. cerevisiae inactivation in clear and turbid fruit juices. Storage study of surviving populations

Consumer growing demands for high-quality and safe food and beverages have stimulated the interest in alternative preservation technologies. Short-wavelength ultraviolet light (UV-C, 254 nm) has proven to be useful for the decontamination of a great variety of clear juices while improving their quality compared to traditional thermal treatments. Suspended solids and coloured compounds in turbid juices, diminish light transmission. The use of UV-C under a hurdle approach, may be a promising strategy for their treatment. The purpose of this study was to analyse Escherichia coli ATCC 25922, Saccharomyces cerevisiae KE 162 and Lactobacillus plantarum ATCC 8014 inactivation in clear pear juice (PJ), turbid orange-tangerine (OT) and orange-banana-mango-kiwi-strawberry (OBMKS) juices processed by single UV-C (390 mJ/cm2, 20 °C) and UV-C assisted by mild heat (UV-C/H, 50 °C) at pilot-scale in a coiled tubing unit and stored under refrigeration (5 °C). Inactivation studies were also conducted in peptone water (PW) and model solution (MS). The adequacy of the Coroller, Weibull and Biphasic Plus Shoulder models was studied. UV-C was highly effective in PW, MS and PJ, achieving up to 5.5-6.3-4.7, 4.8-5.1-4.6 and 4.4-5.5 log reductions for L. plantarum, E. coli,and S. cerevisiae, respectively. Whereas, a moderate inactivation by single UV-C was recorded in the turbid blends, reducing up to 2.4-3.8-1.6 and 3.6-3.7-1.3 log-cycles in OT and OBMKS, respectively. When the UV-C/H treatment was applied, high bacterial inactivation was observed achieving 5.2-5.6, 6.3-6.6 and 5.5-6.7 log reductions in OT, OBMKS and PJ, respectively, while 4.6-4.9 log reductions were determined for the yeast in OBMKS and OT, respectively. Thus, additive inactivation effects between UV-C and H were observed. All the models tested gave useful information regarding the existence of microbial subpopulations with varying resistances. However, the cumulative Weibull distribution function was the most versatile one, fitting inactivation curves with different shapes. Additionally, the frequency distributions of resistances showed that UV-C/H not only increased the UV-C microbicidal effect but changed the distribution of inactivation times. Principal component analysis revealed that UV-C effectiveness was associated to low particle size, a⃰, turbidity and high UV-C transmittance. An increase on the inactivation of treated bacterial populations was recorded along storage, while no yeast recovery was observed, thus emphasizing the contribution of refrigerated storage to microbial inactivation. Microbial inactivation in clear and turbid juices achieved by UV-C (390 mJ/cm2) assisted by mild heat (50 °C) and subsequent refrigerated storage may represent an useful alternative for multiple applications in the juice industry.

Annelida, a Robot for Removing Hydrate and Paraffin Plugs in Offshore Flexible Lines: Development and Experimental Trials

Summary Methane hydrates and paraffin plugs on flexible lines are concerns in offshore production. They may stop wells for months, causing high financial losses. Sometimes, operators use depressurization techniques for hydrate removal. Another strategy is using coiled tubing or a similar unit to perform local heating or solvent injection. However, frequently these strategies are not successful. In those cases, a rig may perform the operation, or the line may be lost. We developed a robotic system to perform controlled local heating and remove obstructions. The system developed can access the line from the production platform. It uses a self-locking system to exert high traction forces. An umbilical with neutral buoyancy and low friction coefficient allows significant friction reduction. It allows moving upward and in pipes with a large number of curves. Coiled tubing and similar units cannot do that. Carbon fiber vessels and compact circuits give the flexibility to move inside 4-in. flexible pipes. In addition, a novel theoretical model allows the cable traction calculation using an evolution of the Euler-Eytelwein equation. Experimental tests validated this model using curved pipes, both empty and filled with fluid, and using different loads. Experimental tests also confirmed the external layer traction resistance. Furthermore, the carbon fiber vessels were pressure tested, indicating a collapse resistance of 57 MPa (8,300 psi). Besides, exhaustive tests of the onboard electronics and the surface control system guarantee the communication reliability. In addition, a theoretical model allowed the design of the 25 kN (5.6 kip) traction system considering the self-locking system, the contact with the wall, and a diameter range. Four prototypes allowed us to compare hydraulic and electric drive systems, validate the self-locking mechanism up to its limit, analyze the hydraulic system for leg opening and translation, and prove the traction capacity. Finally, a theoretical model allowed the local heating system and the temperature to increase. The experimental validation of the system on a cooled environment demonstrated its ability to increase temperature. Further, it allowed the obstruction removal in a controlled manner, avoiding damage to the polymeric layer of the flexible line.

Optimization of coiled tubing nozzle for sand removal from wellbore

Production is hampered by sand and scale that impede flow and require intervention. Although coiled tubing jetting tools have been very successful in wellbore cleaning operations, the coiled tubing unit has certain limitations and constraints. The fluid pumping pressures of fluids at the wellhead are limited to the normal pressure of pump, whereas some sand types and scales require a very high shear force to break and disintegrate. The dimensions of the coiled tubing unit nozzle size are directly related to the diameter of the production tubing. The present work consists in designing the nozzle of coiled tubing jetting tool with different dimensional parameters and analysing the design of the nozzle for required high outlet pressure, flow rate and velocity at various inlet pressures. Numerical technique was used to analyse the flow of fluid through the nozzle. The different port diameters and cone angles between 0.09 and 0.125 inch and 15° and 45°, respectively, were simulated. The effects of these parameters on the outlet pressure, the mass flow at the outlet and the outlet velocities were predicted and analysed. Inner nozzle diameters smaller than 0.75 inch gave good results, and the 1 inch inner diameter gave lower performance. Therefore, the lower diameter nozzle provides better performance. Decreasing the number of ports from seven to five did not create a big difference in nozzle performance, as the seven ported nozzles provide slightly better performance.

Method of Oil and Gas Fields Construction on the Continental Shelf of the Arctic Seas

In this article we consider the problem of field development on the continental shelf consisting in technological complexity and high capital investments of construction of sea oil and gas constructions in water areas of the Arctic seas. We consider the main advantages of a mine and tunnel way of arrangement of sea oil and gas fields as more effective and economic method of field development. We analyse conditions and possibilities of application of tunneling shield for construction of a tunnel under a seabed. We analyse a possibility of operation of coiled tubing unit for development of wells. We offer the perspective way of construction of underwater oil and gas construction combining building of an underground tunnel under a seabed by means of a tunnelling shield and application in a tunnel of the coiled tubing equipment for well-drilling.

Advances in Dendritic Acidizing Reveal Light at the End of the Tunnel

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 189945, “Dendritic Acidizing Update: The Light at the End of the Tunnel,” by C. Dean Wehunt, SPE, Stefan K.K. Lattimer, SPE, and Darren R. McDuff, SPE, Chevron, prepared for the 2018 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, USA, 27–28 March. The paper has not been peer reviewed. Dendritic acidizing (DA) has a long history in the oil industry, going back at least to the 1980s. Significant technical advances include single-trip multitunnels using only acid-pumping equipment and a coiled-tubing (CT) unit, simultaneous tunnel creation, and improved parameter modeling and optimization. This paper provides an update on recent advances for DA methods, also known as acid tunneling, presenting a comprehensive review of published information for three different tunneling methods. Introduction A well with multibranching major tunnels and a superimposed structure of wormholes emanating from the main tunnels has been called a dendritic well. This paper refers to methods that include the use of acids to construct such a well as DA. DA methods can be thought of as a hybrid between multilateral wells with many short branches with low skin factors and matrix acid jobs with very long primary wormholes and many branching wormholes from the primary wormholes. A conceptual example of a horizontal well section with formation tunneling and DA with branching wormholes adjacent to the primary tunnels is shown in Fig. 1. Many different methods are used to form small-diameter lateral branches from a parent wellbore. The methods are differentiated by characteristics such as requirements for workover rigs, CT rigs, and deflector shoes for tunnel initiation; acid use in the process; and primary tunnel creation method. Method A Method A uses a proprietary small-diameter CT unit to deploy a jet nozzle on a flexible, retractable hydraulic hose. The method uses mechanical energy to blast the formation during tunnel creation and, in some cases, also uses acid either while jetting or while retrieving the jetting nozzle to chemically assist with tunnel creation and reduce the skin factor adjacent to the formation tunnels. Method A can be applied in either openhole (OH) or cased-hole completions. In cased-hole applications, a deflection shoe must be run on a work string using a conventional workover rig, and then a hole must be cut in the casing with a separate milling tool. After the milling tool is retrieved by the proprietary CT unit, the jetting nozzle begins jetting a tunnel perpendicular to the well. Although the milling step is not required for OH applications, the deflection shoe must still be used. The jetting nozzle is deployed on a flexible tool that is kept perpendicular to the well by tension on the hose. The tension is also what pulls the hose into the tunnel, so Method A is a pull-the-nozzle method. Hose tension is created because there are rearward-discharging jets with greater discharge area than the erosional jet discharging toward the tunnel tip.

E&P Notes (November 2017)

E&P Notes Permian Winning Streak Could Be Running Out Stephen Rassenfoss, JPT Emerging Technology Senior Editor Hot shale plays tend to fall short of expectations after a few years, and the Permian Basin will be the next big test of the pattern. A recent technical paper by Robert Clarke, research director for Lower 48 Upstream for Wood Mackenzie, questions whether future drilling in the Permian will hit 5 million B/D in 2025 as the consultancy has predicted. Based on what he has been learning recently, some of it reported in SPE technical papers, the actual results could be worse or better, depending on how well the industry solves the problems that will come with intensive development in the Permian. Startup Aims To Advance Rocket Fuel Technology for Fracturing Stephen Whitfield, Senior Staff Writer A startup company in Canada is developing a tool that may help operators realize savings in resources and manpower in their fracturing operations. The PSI-CLONE tool from RocketFrac Services uses a proprietary solid rocket fuel mixture as a propellant fracturing mechanism which eliminates the need for significant water volumes. When loaded into the tool, deployed down a well, and ignited, the propellant releases high-pressure gas and creates enough pressure to produce fractures at targeted sites along the wellbore. The PSI-CLONE tool, which holds the propellant, is reusable. Once the propellant has burned out completely, the tool can be reloaded with another block of fuel. The company states that the system requires a single coiled tubing unit, as opposed to the multiple pumper trucks and water tanks used for hydraulic fracturing, and requires three to five onsite personnel Total Signs Deal With Chevron for Gulf of Mexico Acreage Supermajor Total increased its footprint in the US Gulf of Mexico, capturing seven prospects operated by Chevron. The agreement covers 16 blocks. Total, which recently increased its stake in the US Gulf of Mexico with its takeover of Maersk Oil, will participate in the seven wells through sharing between 25–40% interest. The prospects cover two promising plays: the Wilcox in the central Gulf of Mexico, next to the Anchor discovery; and the Norphlet, in the eastern Gulf of Mexico, near the Appomattox discovery. The first well already spudded in late July on the Ballymore prospect in the Mississippi Canyon. Energy Panel: Efficiency Focus Still Necessary in an Era of Transition Stephen Whitfield, Senior Staff Writer The oil price downturn has changed the way the oil and gas industry does business, and a panel of analysts and industry executives said that reinvention and creativity will be essential to surviving in a new reality. Held at the Global Energy Transitions Summit on the Rice University campus, the panel discussion featured an extensive look at how companies have managed to stay afloat in the current economic landscape. In September, oil prices reached their highest levels since April, but while industry hopes to see that figure sustain above $50/bbl and possibly reach $60, the panelists cautioned against getting overly enthusiastic. Greg Hill, president and COO of Hess, said “lower for longer” was still the primary factor behind his company’s operational strategy, and that it is not advantageous to build a business plan based on the possibility of future oil price growth.

Reliability Evaluation for Improved Screw Dies of Coiled Tubing Unit Injector

Reliability Evaluation for Improved Screw Dies of Coiled Tubing Unit Injector

Novel Viscosity Reducer Aids Removal of Scale From Electrical Submersible Pumps

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 173928, “Removal of Organic and Inorganic Scale From Electrical Submersible Pumps,” by M. Ramones, R. Rachid, SPE, D. Flor, L. Gutierrez, and A. Milne, SPE, Schlumberger, prepared for the 2015 SPE Artificial Lift Conference— Latin America and Caribbean, Salvador, Brazil, 27–29 May. The paper has not been peer reviewed. Rigless coiled-tubing-unit (CTU) interventions can be effective in returning to production wells that have lost electrical-submersible-pump (ESP) efficiency because of organic, inorganic, or mixed scale deposits. Such operations extended the average ESP run life from 40 to 140 days and eliminated the need for workover (WO) rigs. A heavy-crude viscosity reducer (HCVR) is recommended as part of these treatments, to improve the cleanup process. Introduction Recent work with crude-oil viscosity reducers has shown that both inorganic and organic deposits can be removed by spotting/jetting with coiled tubing without the need of a WO rig. When a treating fluid containing the viscosity reducer is mixed with highly viscous crudes, it creates a water-external pseudoemulsion, which decreases the apparent viscosity of the crude by several orders of magnitude, removing more than 60% of the heavy crude from the surface of the scale and accelerating the dissolution of organic deposits. This enables the chemical treatment to dissolve the inorganic deposits, allowing the pump to be restarted without the need to pull out the completion. The new fluid systems have made it possible to remove organic and inorganic deposits systematically from ESPs, extending the average run life from 40 to 140 days, and to eliminate the requirement for WO rigs, with an average rig-cost saving of 6 days per well and an average saving of USD 1.5 million in deferred production. Problem Definition Organic or inorganic deposits can occur in different parts of the petroleum system, including the reservoir, well perforations, artificial-lifting equipment, and production lines. Scales are inorganic deposits that are formed when the saturation of the produced water is affected by changes in temperature and pressure conditions, creating significant reduction in oil-production rates or even plugging the entire production system. On the other hand, viscous oils that are exposed to significant pressure drop are the source of organic-material deposition, the most common being paraffins and asphaltenes. These organic materials can be defined as hydrocarbons with high molecular weights that are hard to dissolve and that can also create sludge when in contact with acid systems.

New geothermal well-completion and rework technology by laser

Our research team has developed a new well completion and rework technology involving lasers. The system is made up of a high-power laser generator and a custom-designed directional laser drilling head. The laser head is attached to a coiled tubing unit to maximize production and to carry out special downhole tasks. In this phase of the development effort, laser technology is particularly well suited to cost-efficiently drill short laterals from existing wells in a single work phase, drilling through the casing and cement as well as the formation. The technology, which is an extended perforation solution, enables a more intensive interaction with the downhole environment and supports cutting edge subsurface engineering scenarios such as barite removal. Laser-induced heat treatment appears to be a suitable alternative to effectively remove the almost immovable deposits and scales from thermal water-well pipes.

Targeted Fracturing Using Coiled-Tubing-Enabled Fracture Sleeves

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 154391, ’Reducing Operational Time, Fluid Usage, Hydraulic Horsepower, Risk, and Downtime: Targeted Fracs Using CT-Enabled Frac Sleeves,’ by Luis Castro, SPE, Thomas Watkins, SPE, Brian Bedore, SPE, and Robert Holt, Baker Hughes, and Greg Manuel, Pioneer Natural Resources, prepared for the 2012 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, 27-28 March. The paper has not been peer reviewed. Unconventional reservoirs are an increasingly important part of the hydrocarbon production pool in North America. Because reservoir conditions typically require hydraulic fracturing for economical production, a significant amount of resources are focused on making the fracturing process faster and more efficient and on lowering its environmental impact. A novel technique to create targeted annular hydraulic fractures rapidly involves deploying an activation tool on coiled tubing (CT) to open fracture sleeves in a horizontal well. The new technology uses fracture sleeves that are activated swiftly using a CT bottomhole assembly (BHA). The system, already used in thousands of fracturing stages in Canada, speeds up the completion process, uses less fluid, minimizes risks, and reduces overall downtime. Introduction Unconventional reservoirs in the United States are commonly stimulated using what is known as the “plug-and-perf ” (P&P) method. This method requires a tubing-conveyed perforating (TCP) device run, typically on CT, for the first stage to open a conduit for pumping down the casing. The first stage of the fracturing treatment is then pumped down through the open perforations. Once completed, a composite plug and perforating guns are run on wireline to isolate the first fracture stage and to perforate intervals in the second stage (each interval is commonly referred to as a “cluster”). Running wireline in horizontal wells requires pumping fluid from surface to push the wireline BHA through the wellbore like a piston. After retrieving the wireline from the well, the subsequent fracture treatment is pumped. This process is repeated until all stages are completed. After the fracture spread moves off of the location, a CT unit is commonly brought in to mill the composite plugs and allow the well to produce. Although this method is the one most commonly used, it has drawbacks. P&P fracs are time consuming: They require numerous days on location to prepare the well (i.e., running the TCP device, known as a toe-shoot), complete all the stages designed for the fracturing treatment, and finally mill the plugs.