Radio frequency electromagnetic wave communication in deep oil wells

Corrosion problems of deep well tubings and their control measures are discussed. As one of the economical solutions, metal-lined tubings are proposed. It is shown that the metal liner can be tightly fitted by the newly developed thermo-hydraulic fit method. The selection of corrosion-resistant material for the liner is discussed. Some designs of the tubing joint and their manufacturing methods pre proposed. Introduction With the seriousness of an energy shortage, the drillings of oil and gas wells have become more active. In the last few years, the number of drilled wells has increased rapidly as shown in Fig. 1. It should be noted that eighty percent of these wells were drilled in the United States. Fig. 2 shows the depth distribution of oil and gas wells drilled in the United States in 1977. It can be seen that the numbers of oil and gas wells are about the same, but, in general, there are more gas wells at deeper depths than oil wells. As shown in Fig. 3, well depth increases each year, and recently an exploratory well deeper than 10,000 m has been drilled. As the well depth increases, the down hole pressure and temperature rise. For instance, in some severe wells at a depth of 6,000 m, the pressure and temperature are more than 1,000 bar and 200°C respec. tively. Therefore, the strength of the tubings used in such severe conditions is a very important factor for deep wells because they have to sustain their ownweight also. Figure 4 diagrammatically illustrates the transitions of design conditions with the increaseof well depth. Figure 5 shows the relationship between well depth and axial and hoop stresses of API standard tubings with various pipe 'dimensions. It isknown roughly that the strength of class P-I05 is required for the tubing of a 6,000 m well. Another substantial problem in deep oil and gas wells is corrosion. This is mainly due to H2S and C02 which are contained in crude oil and natural gas The density of these contaminants is increased with well depth, and, together with high pressure and high temperature, the corrosion reaction is accelerated. To solve all the above problems in deep wells, a new type of economical, high strength tUbing which has high corrosion resistance is expected. At present a super Ni alloy tubing, which is extremely expensive, tends to be used. As a solution, the authors propose the Tight Fit Tubing (hereinafter referred to as TFT) which is lined inside with corrosion-resistant alloy to meet the above three requirements for the tubing of deep wells. The thermo-hydraulic fit method used here for TFT has been developed to produce the corrosionresistant pipe, TFP, for corrosive flow lines as reported in Ref. 1.

As development of deep oil reservoir, more and more deep and ultra-deep wells, of which the chief lifting method is sucker-rod pumping system, are drilled. There often exist problems for systems above such as high load and low pumping efficiency. Because of low density and high intensity of carbon fiber rod, polished rod load can be decreased by using carbon fiber rod to increase safety factor. Meanwhile, since elastic modulus of carbon fiber rod is low, stroke loss will be increased by unreasonable lifting parameters. Test of carbon fiber rod was conducted in Xinjiang oil field in order to verify the feasibility of carbon fiber rod in deep oil wells and evaluate load shedding and energy saving effect. To lighten field test workload, a 3D rod mechanical model was built to simulate conditions of different production parameters. From the results of field test and simulation, it is indicated that carbon fiber rod owns better load shedding capacity and higher strength intensity; under the condition of deep wells, more stroke loss may be caused by carbon fiber composite rod. For some conditions, pumping efficiency is low, even worse, rod lock problems like gaslock may appear; reasonable combination of rod string and production parameters can improve the feasibility of carbon fiber rod.

Effective control of shale swelling and lost circulation using drilling fluid is considered the dominant strategy for maintaining borehole stability, especially drilling operations in deep oil and gas wells. In this work, a hybrid silicate that contains lithium silicate and potassium methyl silicate (PMS) was employed as a film-forming additive to reduce shale hydration and filtration loss in the high-temperature drilling fluid. Scanning electron microscopy (SEM) results revealed that a dense quartz crystal film coating on the shale can be formed in a hybrid silicate solution when the temperature exceeds 150 °C. The in situ-formed film on the shale surface with a thickness of 60–130 μm was composed of fibrous crystalline silica. Furthermore, the aqueous hybrid silicate exhibited enhanced hydration inhibition ability by preventing water invasion of the formation. Aqueous hybrid silicate with a concentration of 0.5–3 wt % lithium silicate and 0.1–0.2 mol/L PMS was first chosen to obtain the optimum concentration according to the hydration inhibition ability and film formation characteristics. The hybrid silicate was added into a drilling fluid formulation applicable in high-pressure and high-temperature conditions, and the rheological characteristics and filtration properties were investigated. The results confirmed that drilling fluids with the addition of hybrid silicate can mitigate variation of viscosity and yield point before and after aging at 180 and 220 °C. Besides, the filtration behavior was also improved by adding hybrid silicate into the drilling fluid. A lower filtration loss was observed at the concentration of 1.0 wt % lithium silicate and 0.2 mol/L potassium methyl silicate, which showed 63 and 50% HPHT fluid loss reduction for unweighted and weighted formulations at 205 °C and 3.5 MPa, respectively. In addition, the drilling fluid featured stable rheological and filtration properties and excellent shale hydration inhibition characteristics when exposed to high temperatures, making it a promising candidate for drilling in deep oil and gas wells.

1-(2-Aminoethyl)-1-dodecyl-2-hexadecyl-4,5-dihydro-1H-imidazol-1-ium (PQI) and 1-(2-aminoethyl)-1-dodecyl-2-heptadecyl-4,5-dihydro-1H-imidazol-1-ium (SQI) are two ionic liquids compounds. FTIR, 1HNMR spectroscopic techniques were used to confirm PQI and SQI chemical structures. Quantum chemical calculations (QCC), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) are various techniques which were utilized to evaluate PQI and SQI compounds as corrosion inhibitors for X-65 carbon steel in oil well formation water. The outcome experimental results showed that as the concentration of PQI and SQI compounds had increased, the inhibition efficiency increased gradually till reaching maximum value (94.68%) at 500 ppm of SQI compound. Surface morphology techniques (SEM, EDX) confirmed the formation of protective film on the carbon steel surface. PQI and SQI compounds were adsorbed on the carbon steel surface according to Langmuir adsorption isotherm model.

Drilling oil wells is a costly, complex and high risk operation, especially for many wells whose depths can be at least several thousand feet. To minimize the cost and risk involved in drilling, typically there are several sensors mounted near the drill bit, to measure important parameters such as temperature and pressure around the drill bit. The collected information needs to be sent to the surface, to assist the driller with controlling and steering the drill bit. Compared to the use of highly expensive and vulnerable cables for wired communication in deep oil wells, or very low rate communication using pulses of mud in wells, transmission of information using acoustic signals thru the drill string is a feasible and promising method. In this paper, we use a drill string acoustic communication testbed, where the receiver is a strain sensor. This sensor measures local fractional displacements due to received vibrations. Using experimental data, we study key characteristics of a drill string channel impulse response, sensed by a strain sensor. We also demonstrate how the strain channel response structure can control the communication system performance. [This work was supported in part by the National Science Foundation (NSF), Grant IIP-1340415.]

In one of ADCO's mature fields several horizontal oil wells have ceased to flow due to the high water cut. In order to accelerate data acquisition on well, reservoir and ESP performance at these higher water cuts, an ESP pilot project was performed in three wells. ADCO's past experience with ESPs in some of the main fields in deep, high temperature and GOR wells (250 deg F and 700 scf/bbl, respectively) has been poor and discouraging. To ensure that future ESP applications in these fields are successful, a comprehensive review was conducted by ADCO and industrial shareholders (ISH) to determine the root causes of the previous failures and recommend methods to improve current practices. In accordance with the recommendations, a multidisciplinary team was set up to plan and execute the ESP pilot project. The project team was responsible for the tendering, designing and engineering aspects, gathering the reservoir data, finalizing the completion strategy, equipment sizing, installation, commissioning and monitoring. The result of this effort was the successful installation and running of ESPs in two of the field's oil wells. The project success is of paramount importance as it can lead the way for future ESP applications in similar harsh downhole conditions. This paper discusses ADCO's approach to overcome the past difficulties it had in running ESPs in deep and hot oil wells starting from the review up to the installation and commissioning.

In the last years, the use of FPSOs is becoming a widespread technology because it is a practical and cheap system for the exploitation of small oilfields or deep water oil wells, i.e. oilfields for which the installation of pipelines is too expensive. Recently, growing attention has been devoted to the advanced design of vessels able to operate effectively even when the system is subject to abrupt movements. The study of the behavior of process fluids (gases and liquids) and their mutual system is subject to abrupt movements. The study of the behavior of process fluids (gases and liquids) and their mutual Fluid Dynamics (CFD) techniques. In this paper, a fluid dynamic model of a FPSO separator is developed using a CFD methodology. This model is able to predict the behavior of the fluid and of their interfaces within the separators to be installed on FPSOs. Several simulations were carried out to study the behavior of the fluids and the efficiency of two vessel types (reboiler and surge vessel). The vessels are subjected to the forcing conditions typical of an ocean storm, i.e. surge, sway, heave accelerations and roll, pitch and yaw rotations, gathered from real historical data. Transient simulations were carried out applying time-varying accelerations to the vessel. The methodology is described in order to give general guidelines for the FPSO simulations. The main technical contributions of this study are:the understanding of the behavior of the liquid in the separator mounted on FPSOs in different storm conditions;the validations of FPSO separator design to assure their functionality even during heavy storms;the A development of a numerical methodology to implement complex CFD simulations in the presence of time-varying boundary conditions which models the effect of sea movements on on-board ship devices. Introduction The ever increasing research regarding new technologies for the exploitations of off-shore oil wells has led to the creation of FPSO in the 1970s. This technology allows the exploitation of oil wells for which the installation of an oil platform and pipeline is too expensive, is not technically advantageous or, in the case where hydrocarbons must be stored, until it can be uploaded onto a tanker or transported through a pipeline. The FPSOs can be either decommissioned tankers or purpose-built ships used for receiving, processing and storing the hydrocarbons produced by nearby platforms or subsea wells. Several separators and oil treatment systems are installed on an FPSO. These systems are intended to separate water from oil and gas extracted and, subsequently, to process them. Once processed, the fluids are stored awaiting to be transferred. The most common technique to separate oil, water and gas is the use of large gravity-based vessels (separators). The FPSOs are ships that perform their functions by being moored permanently so the FPSOs and all the systems installed on-board are subjected to wave motion. These movements, that can be very violent i.e. during an ocean thunderstorm, cause sloshing within the vessels. The slosh motion can reduce the separator's efficiency and cause great damage to the structure. It is therefore necessary to study the behavior of the fluids within the separators. The design verification of the separators to be installed on FPSO can be carried out by numerical simulations. The numerical simulations are a cheap instrument to verify the performance of the separators and the design choices without the need to create a prototype.

Laser rock spallation is a rock removal process that utilizes laser-induced thermal stress to fracture the rock into small fragments before melting of the rock occurs. High intensity laser energy, applied on a rock that normally has very low thermal conductivity, concentrates locally on the rock surface area and causes the local temperature to increase instantaneously. The maximum temperature just below the melting temperature can be obtained by carefully controlling the laser parameters. This results in a local thermal stress in subsurface that is enough to spall the rock. This process continues on a new rock surface with the aid of the high pressure gas purging blowing away the cracked fragments. Laser parameters that affect the laser spallation efficiency will be discussed in the paper. Also reported in the paper is the multi laser beam spot spallation technique that has been developed for potentially drilling large diameter and deep gas and oil wells.

Water-based drilling fluids comprising different clays (bentonite, saponite, and sepiolite) have been autoclaved in the temperature range of 300–600°F (149–316°C) under appropriate confining pressures in order to simulate the conditions encountered while drilling deep oil and gas wells. The clay mineral saponite represents the magnesium analog of montmorillonite which is the aluminous clay mineral in bentonite. Both montmorillonite and saponite are characterized by a swelling silicate lattice and an excess layer charge. Morphologically, saponite and montmorillonite are similar and they consist of thin platelets and films mostly in the micron-size range. Sepiolites are similar in chemistry to saponites but they possess a fibrous morphology and a neutral lattice. These basic characteristics of the clays are found to lend different rheological and wall-building properties to the drilling fluids. Saponite fluids display much higher viscosities and significantly lower fluid losses at high temperatures. Saponite fluid was also more stable than bentonite fluid at high temperatures and in the presence of common Na, K, and Ca salts and hydroxides due to the nature of reactions between these compounds and bentonite. Mixing fibrous sepiolite with saponite enhances the viscosity of these fluids in the presence of common salts. At high temperatures sepiolite readily converts to a smectite and improves the fluid rheology and fluid losses.

A comprehensive analysis on the longitudinal fracture in the tool joints of drill pipes

Modern forecast, exploration and development of hydrocarbon deposits within natural carbonate reservoirs of buried bioherm (reef) structures in the north of the Irkutsk region and the Sakha Republic (Yakutia) areas within the NepaBotuoba Anticline apply the most advanced technologies of 3D seismic exploration and geoelectric prospecting supplemented with a set of new interpretation approaches and analysis attributes contrasted against wide range of well logging data. The recent discoveries of hydrocarbon deposits in the northern reefs shoved the bioherms of the Irkutsk amphitheater in the shadow. The purpose of this research is geological study of biohermal carbonate formations of the Lower Cambrian age in the outcrops of the Bozhekhansky megaswell in the Baikal region. The choice of this object of study is due to the fact that the first oil and gas inflows were obtained from the wells of the Atovskaya, Osinskaya, Birkinskaya, Khristoforovskaya, Balykhtinskaya and Tuturskaya areas. Field geological routes and office processing of data on cuts and polished thin sections of sample surfaces were carried out including microscopic studies in the thin sections of samples and archival collections of cores from deep oil and gas prospecting wells. In 2021–2022, while prospecting in the south of the Irkutsk amphitheater, the authors explored stratified, nodular and columnar stromatolites found within the compound Bozhekhan megaswell of Cambrian carbonate outcroppings. Carbonate intraformational sedimentary breccias identified in the area under investigation feature a great variety in their fragment sizes and inclusions. The stromatolites’ structural features were studied by the cuts and polished thin sections of sample surfaces. Microphytolites were found in the thin sections and described. The authors also took advantage of the opportunity to study an archive collection of the thin sections of VendCambrian and Lower Cambrian carbonate strata from the Akhinskaya area’s wells at the Bozhekhan megaswell and from the Upper-Lena uplift to the north-west. The conducted study implies that Cambrian bioherm outcroppings of the Bozhekhan megaswell-type uplift within the Cis-Baikal trough are, in a sense, model geologic objects. The study of biologic and genetic varieties of Lower Cambrian phytolites, diagnostic features of the organogenic structures, their inner structure and formation processes of the reef ecosystem may provide a region-level prognostic key to the research of Cambrian sediment system in the south of the Siberian platform.

Stimulation of high temperature carbonate gas reservoirs using seawater and chelating agents: Reaction kinetics

Laboratory tests in simulated sour downhole environments performed on a duplex stainless steel show correlation with the field experience for these alloys.

For many years rod pumping has been a desirable artificial lift method for on-shore oil wells. Today, in addition to rod pumps, other artificial lift methods such as gas lift and electrical submersible pumps (ESP) are also available for assisting well production. While rod pumps have been proven to be one of the simplest and most economical choices, when it is not sufficient for high-rate wells, harsh-fluid production, or deep wells, operators turn to other lift methods to produce hydrocarbons to the surface. The selection of appropriate artificial lift methods revolves around many factors, including economics. This paper presents a conceptual and feasibility study of combination of two methods of lifting for production of moderate volumes of oil from deep or ultra-deep onshore wells. It proposes to use an ESP and a sucker rod pumping unit simultaneously to lift fluids. The argument is that to lift from a deep well, with only ESP the cost and housing limitation of the wellbore may become a vital problem. Lifting the hydrocarbons to a certain depth by an ESP system, and then using the rod pump to transport the fluid to the surface may be a solution for deep and ultra deep wells. One of the critical issues in this concept is that rod pump lift is an intermittent lift, but ESP is a continuous lift. This issue has been address with the design of a chamber in between the two systems to accommodate the two lift devices and ensure continuity. This paper presents an example with detailed calculations to provide the technical support to the idea. Even though this approach has not been applied in the field, once proven feasible, the dual lift method can bring a solution with economic value to artificial lift for ultra-deep onshore oil wells.

This work experimentally validates the feasibility of a tactile exploration approach to map harsh environments such as deep sea oil well sites. The recent collapse of the offshore oil-drilling platform Deepwater Horizon in the Gulf of Mexico resulted in the largest marine accidental disaster in history. Initial attempts to control the spill failed because of the very challenging environmental conditions. Knowing the shape and dimensions of the cracks in the leaking structure could have provided critical information to maneuver the Remotely Operated Vehicles. Here, a method developed in our previous work for tactile exploration of oil wells is applied to the problem of mapping underwater oil well sites. This method only requires a manipulator provided with joint encoders, and does not need any range, tactile or force sensor. This makes the approach robust and directly applicable to the mapping of underwater sites. This paper focuses on the experimental validation of the approach. Several experiments are described, showing the effectiveness of the approach in mapping unknown structured environment in short time, and demonstrating its reliability under very harsh conditions, such as irregular environment surfaces, surrounding viscous fluids and high manipulator joint backlash.