Recent Case Histories of Multilateral Systems Enabling Thru Tubing Intervention in the Middle East

Historically, the ability to perform intervention on multilateral wells has been limited. While multilateral (ML) well construction technologies have progressed to a high level of reliability, multilateral systems that enabled intervention during the life of well had a more limited track record. Intervention outcomes after prolonged periods of production were less consistent. This lack of technologies with sufficient intervention case histories meant that generally multilateral well architecture was not selected in applications where thru tubing intervention was a requirement. In recent years, multilateral well architecture has continued to increase in demand, with more ML wells drilled and completed in the last five years than any other five-year period in the technology's history. With this increased demand has come industry enthusiasm to further mature its intervention capabilities. This paper will review two recent case histories of separate multilateral well completion systems that enable intervention. This opens up new potential for the industry to take advantage of the cost reductions achieved with multilaterals in a much larger scope of well applications. Two separate completion systems will be covered in this paper, System A installed in a cemented multilateral junction and system B, a completion that creates a hydraulically isolated junction via either a dual string completion or a single string completion that splits into two strings. These case histories were exectuted in 2017 to 2019, and interventions were performed after one to two years of production. Detailed in each case study will be an overview of the equipment, the operational sequence, intervention outcome, and any lessons learned or improvements. The systems have demonstrated themselves as a reliable method to access laterals in non-ideal downhole environments where debris is present after the well has been on production. The tubing sizes for the case studies are 3-1/2" and 4-1/2". In each of these wells, the following operations have been successfully performed: drift testing, acid stimulation through coil tubing and breaking of a ceramic disc. Both slickline and coil tubing have been used for the interventions and in some cases with tractors. Junction inclinations range from 1 to 43 degrees. Plans for ongoing installations for the systems are being executed in the Middle East Region. Further, expansion of the system A capabilities by integrating it with other existing technologies is also planned. This will enable projects such as the installation of a trilateral well with flow control and intervention for each individual leg, and also the conversion of existing single bore wells to multilateral with intervention capability.

Waterbird solves the string-pull test

String-pulling is among the most widespread cognitive tasks used to test problem-solving skills in mammals and birds. The task requires animals to comprehend that pulling on a non-valuable string moves an otherwise inaccessible food reward to within their reach. Although at least 90 avian species have been administered the string-pull test, all but five of them were perching birds (passeriformes) or parrots (psittaciformes). Waterbirds (Aequorlitornithes) are poorly represented in the cognitive literature, yet are known to engage in complex foraging behaviours. In this study, we tested whether free-living ring-billed gulls ( Larus delawarensis ), a species known for their behavioural flexibility and foraging innovativeness, could solve a horizontal string-pull test. Here, we show that 25% (26/104) of the ring-billed gulls that attempted to solve the test at least once over a maximum of three trials were successful, and that 21% of them (22/104) succeeded during their first attempt. Ring-billed gulls are thus the first waterbird known to solve a horizontal single-string-rewarded string-pull test. Since innovation rate and problem-solving are associated with species' ability to endure environmental alterations, we suggest that testing the problem-solving skills of other species facing environmental challenges will inform us of their vulnerability in a rapidly changing world.

Superstring Backgrounds in String Geometry

String geometry theory is a candidate of the nonperturbative formulation of string theory. In order to determine the string vacuum, we need to clarify how superstring backgrounds are described in string geometry theory. In this paper, we show that all the type IIA, IIB, SO(32) type I, and SO(32) and E 8 × E 8 heterotic superstring backgrounds are embedded in configurations of the fields of a single string geometry model. In particular, we show that the configurations satisfy the equations of motion of the string geometry model in α ′ ⟶ 0 if and only if the embedded string backgrounds satisfy the equations of motion of the supergravities, respectively. This means that classical dynamics of the string backgrounds are described as a part of classical dynamics in string geometry theory. Furthermore, we define an energy of the configurations in the string geometry model because they do not depend on the string geometry time. A string background can be determined by minimizing the energy.

Balancing Straight-line Programs

We show that a context-free grammar of size that produces a single string of length (such a grammar is also called a string straight-line program) can be transformed in linear time into a context-free grammar for of size , whose unique derivation tree has depth . This solves an open problem in the area of grammar-based compression, improves many results in this area, and greatly simplifies many existing constructions. Similar results are shown for two formalisms for grammar-based tree compression: top dags and forest straight-line programs. These balancing results can be all deduced from a single meta-theorem stating that the depth of an algebraic circuit over an algebra with a certain finite base property can be reduced to with the cost of a constant multiplicative size increase. Here, refers to the size of the unfolding (or unravelling) of the circuit. In particular, this results applies to standard arithmetic circuits over (noncommutative) semirings.

Crosstalk Suppression for Fault-tolerant Quantum Error Correction with Trapped Ions

Physical qubits in experimental quantum information processors are inevitably exposed to different sources of noise and imperfections, which lead to errors that typically accumulate hindering our ability to perform long computations reliably. Progress towards scalable and robust quantum computation relies on exploiting quantum error correction (QEC) to actively battle these undesired effects. In this work, we present a comprehensive study of crosstalk errors in a quantum-computing architecture based on a single string of ions confined by a radio-frequency trap, and manipulated by individually-addressed laser beams. This type of errors affects spectator qubits that, ideally, should remain unaltered during the application of single- and two-qubit quantum gates addressed at a different set of active qubits. We microscopically model crosstalk errors from first principles and present a detailed study showing the importance of using a coherent vs incoherent error modelling and, moreover, discuss strategies to actively suppress this crosstalk at the gate level. Finally, we study the impact of residual crosstalk errors on the performance of fault-tolerant QEC numerically, identifying the experimental target values that need to be achieved in near-term trapped-ion experiments to reach the break-even point for beneficial QEC with low-distance topological codes.

Drilling System Optimization Leads to Expedited Wells Delivery

On a Deep Gas Project in the Middle East, it is required to drill 3500 ft of 8-3/8" deviated section and land the well across highly interbedded and abrasive sandstone formations with compressive strength of 15 - 35 kpsi. While drilling this section, the drill string was constantly stalling and as such could not optimize drilling parameters. Due to the resulting low ROP, it was necessary to optimize the Drill string in order to enhance performance. Performed dynamic BHA modelling which showed current drill string was not optimized for drilling long curved sections. Simulation showed high buckling levels across the 4" drill pipe and not all the weight applied on surface was transmitted to the bit. The drilling torque, flowrate and standpipe pressures were limited by the 4" drill pipe. This impacted the ROP and overall drilling performance. Proposed to replace the 4" drill pipe with 5-1/2" drill pipe. Ran the simulations and the model predicted improved drill string stability, better transmission of weights to the bit and increased ROP. One well was assigned for the implementation. Ran the optimized BHA solution, able to apply the maximum surface weight on bit recommended by the bit manufacturer, while drilling did not observe string stalling or erratic torque. There was also low levels of shocks and vibrations and stick-slip. Doubled the on-bottom ROP while drilling this section with the same bit. Unlike wells drilled with the previous BHA, on this run, observed high BHA stability while drilling, hole was in great shape while POOH to the shoe after drilling the section, there were no tight spots recorded while tripping and this resulted in the elimination of the planned wiper trip. Decision taken to perform open hole logging operation on cable and subsequently run 7-in liner without performing a reaming trip. This BHA has been adopted on the Project and subsequent wells drilled with this single string showed similar performance. This solution has led to average savings of approximately 120 hours per well drilled subsequently on this field. This consist of 80 hours due to improved ROP, 10 hrs due to the elimination of wiper trip and a further 30 hrs from optimized logging operation on cable. In addition, wells are now delivered earlier due to this innovative solution. This paper will show how simple changes in drill string design can lead to huge savings in this current climate where there is a constant push for reduction in well times, well costs and improved well delivery. It will explain the step-by-step process that was followed prior to implementing this innovative solution.

Innovative Remediation Techniques for Restoring Well Integrity with Coil Tubing Patch

Well BO-X is located in offshore East Malaysia and was completed as a single string producer on 22nd July 2014. Well BO-X has maximum deviation of 57.5 deg at depth 3,150ft MDTHF. Based on the MIT logs, several leaks have been detected on the string which caused the well unable to flow. Well was flowing for 2 years before identified with multiple leaks due to severe metal loss and high penetration along more than 1,400 ft tubing interval (400 ft above the TRSCSSV and 1000ft below the TRSCSSV). Multiple attempts tried to flow well but failed due to circulation of gas through leak points at tubing. Tubing was found to be leaking at multiple points above TRSCSSV (449 ft MDTHF) with severe pitting / penetration at a single point below between ESP discharge head and TRSCSSV from 2 MIT runs. The leaks were detected at depth (1) 64 ft MDTHF, (2) 126.8 ft MDTHF and (3) 221.2 ft MDTHF. There were also several potential leaks detected along the long string above the top packer Reservoir simulation studies and production rate both indicated that the production tubing leaks is deteriorate and few methods were considered to bring back the optimum production. Tubing pack off system technique was considered as it can deploy with slickline, retrievable and ideal use to isolate tubing leaks however there is potential that more leaks will develop along the production years. Workover as an option to replace the tubing could easily cost millions of dollar (USD) Before surrender the well to workover team, a coiled tubing patch system was designed in a cooperative project involving operator and service company to provide an improved tubing pack off system which can straddle the tubing leaks by using coiled tubing instead of spacer pipe. This coiled tubing patch system was significantly lower cost and keep the functionality of Tubing Retrievable Surface Control Subsurface Safety Valve (TRSCSSV) by installing two straddle packer system – upper straddle packer system to cover leak points above TRSCSSV while another straddle system to cover leak points below TRSCSSV (Fig 1).

NEW METHOD EVALUATION OF DETAIL MATERIAL AND HEAT FLOWS FOR SINGLE STRING CEMENT CLINKER PLANT

Material flow in each main equipment of a cement clinker plant, which is very useful for controlling the process, is impossible to be measured during operation due to very high temperatures. This paper intends to overcome the difficulties associated with the measurement of these material flow values. This study presents a new method of calculating material flow (gas and solid) in each main equipment of a single string conventional suspension preheater type of a cement clinker plant. Using the proposed method, mass flow rate at a clinker cooler, kiln, suspension preheater (SP) and even each cyclone separator can be calculated with a heat conservation error less than 1 %. With the application of the least square method for solving the overdetermined system of mass and heat conservation equations obtained in the cyclones of SP, the flow of gas and solid materials entering and exiting each cyclone that cannot be measured directly in the operating plant can be approached. Based on the operation temperature data of gas and solid flows monitored in the control room of an Indonesian cement plant as a case study, the mass flow rate of gas and solid entering and exiting as well as separation efficiency of each cyclone can be calculated. The results show that the separation efficiencies of cyclones 1, 2, 3 and 4 are 95 %, 91.89 %, 84.09% and 79.51% respectively. Finally, this study will be very useful by providing data that are impossible to gather by a direct measurement in an operating plant, due to a very high process temperature constraint, for operational control needs, new equipment design, process simulation using computational fluid dynamics (CFD) software and even modification of existing equipment. The proposed method can be applied to all types of modern cement clinker plant configurations, either with or without a calciner including the double strings.

String-pulling in the Goffin’s cockatoo (Cacatua goffiniana)

Goffin’s cockatoos, a parrot species endemic to the Tanimbar Islands in Indonesia, demonstrate remarkable cognitive skills across various technical tasks. These neophilic extractive foragers explore objects with their beak and feet, and are skilled in several modes of tool use. In this study, we confronted the animals for the first time with a vertical string-pulling setup, including a set of classic and novel controls. Nine of the 12 subjects, two of which were subadults, immediately interacted with the single-string task, with seven individuals successfully obtaining the reward on their very first attempt. Four different double string discrimination tests with varying spatial relations were used to assess the Goffin’s cockatoos’ apprehension of basic physical task properties. We found significant differences in performance between the respective experimental conditions, as well as the development of side biases. The results suggest that while the birds seem to consider simple cause–effect relationships, there is no evidence for a mental representation of the causal mechanisms underlying the string-pulling tasks, as subjects failed the crossed strings condition out of immediate sight. Finally, we provide suggestions on improving the methodology, and discuss our findings in regard to the Goffin’s cockatoo’s ecology.