Closed-loop well construction optimization (CLWCO) using stochastic approach under time uncertainty

There is a digital step change taking place in well construction today. More and better data will become available for a vast number of analyses. The well construction process is complicated and includes several hundred parameters. There are many inhouse drilling analytics tools used by service and consulting companies. The objective of this paper is to aim at a complete time optimization and to improve health, safety and the environment (HSE) in a time-effective way. In this paper we establish and apply a full approach methodology for closed Loop well construction optimization (CLWCO) under time uncertainty. CLWCO involves six major steps: data gathering,a work-breakdown structure (WBS) in drilling scenarios, time estimation (budget time &technical time),time simulation (MCS&PERT), scenario analysis & optimization and finally updating time model. CLWCO involves three major concepts: optimizing the time plan based on current time knowledge, drilling new wells and collecting time data, finally updating multiple time models based on all of the available data. In the CLWCO step, work breakdown structure (W.B.S), time and controls for new wells are optimized by Monte-Carlo Simulation and program evaluation review technique (PERT). This paper goals are to identify and in best case quantify “the value of Monte Carlo simulation and Program Evaluation Review Technique (PERT) in batch & conventional time drilling optimization” in offshore wells for clients or operating company. Batch drilling does not combine professionally with modern techniques yet.we fill this gap by using modern techniques to optimize and enhance drilling work. We evaluate and analysis above-mentioned approach for batch drilling which has become increasingly prevalent in the petroleum industry as large and small investors alike seek to increase their profit margin. The insight of many of these oil and gas companies was to drill and complete wells using new techniques with the desire of considerable reduction in drilling time and cost for the field. when similar hole sections such as 32″,24″,16″,12 ¼″ and 8 ½″ of different wells were drilled one after the other efficiency and profits would be greatly increased. According to obtained results in closed loop well construction optimization (CLWCO), these methods are successful as it needs less time and cost to drill a lot of wells using the same platform. we simulated a drilling program for the case study of SP field by Monte-Carlo Simulation and program evaluation review technique (PERT),at the end we propose the optimum probable time to do future drilling program in SP field. The time versus depth graph of drilling project show that the improved drilling efficiency for drilling project designed as 11 wells would reduce the total drilling time around 15% in compare of previous drilling projects in phase SP6,SP7 and SP8,totally average drilling time have been improved between 2.5 and 8 days in MCS and PERT simulation technique for each well by using CLWCO.We presented the optimal plan coupling with batch drilling could be implemented in the future phases of SP field, which has resulted in decreasing drilling time to 30 days by using casing-drilling and liner-drilling technology.acceptedVersio

Real-Time Minimization of Mechanical Specific Energy with Multivariable Extremum Seeking

Drilling more efficiently and with less non-productive time (NPT) is one of the key enablers to reduce field development costs. In this work, we investigate the application of a data-driven optimization method called extremum seeking (ES) to achieve more efficient and safe drilling through automatic real-time minimization of the mechanical specific energy (MSE). The ES algorithm gathers information about the current downhole conditions by performing small tests with the applied weight on bit (WOB) and drill string rotational rate (RPM) while drilling and automatically implements optimization actions based on the test results. The ES method does not require an a priori model of the drilling process and can thus be applied even in instances when sufficiently accurate drilling models are not available. The proposed algorithm can handle various drilling constraints related to drilling dysfunctions and hardware limitations. The algorithm’s performance is demonstrated by simulations, where the algorithm successfully finds and maintains the optimal WOB and RPM while adhering to drilling constraints in various settings. The simulations show that the ES method is able to track changes in the optimal WOB and RPM corresponding to changes in the drilled formation. As demonstrated in the simulation scenarios, the overall improvements in rate of penetration (ROP) can be up to 20–170%, depending on the initial guess of the optimal WOB and RPM obtained from e.g., a drill-off test or a potentially inaccurate model. The presented algorithm is supplied with specific design choices and tuning considerations that facilitate its simple and efficient use in drilling applications.publishedVersio

Bridging performances of lost circulation materials (LC-LUBE and mica) and their blending in 80/20 and 60/40 oil-based drilling fluids

In drilling wells, lost circulation, barite sagging, shale swelling, and formation damage are critical problems for the industry. These problems can be controlled by designing appropriate drilling fluids and lost circulation materials. In this study, the performance of 80/20 and 60/40 oil-based drilling fluids (OBMs) was compared based on the lost circulation materials’ (LCMs) bridging performance, filtrate loss, barite sagging, and shale stability. The results show that in terms of LCM stability, the performance of LC-LUBE improved when blended with mica. Both drilling fluids inhibit shale swelling. The overall analysis showed that the 60/40 OBM is better and recommended.publishedVersio

Glidestøp av miljøbetong

Betong er sterkt, bestandig og anvendelig, og regnes som et av verdens mest brukte byggemateriale. Materialet er forbundet med et høyt utslipp av klimagasser, og sementenproduksjonen anslås til å stå for 7-8% av utslippene på verdensbasis. Jordas klima er i forandring som et resultat av økt CO2-utslipp, og det er derfor et høyt fokus på å gjøre betong mer miljøvennlig ved å redusere sementbruken. Miljøvennlig betong regnes som betong der det er gjort tiltak for å redusere klimagassutslippene, hvor hovedfokuset ligger på å erstatte deler av sementen med tilsetningsmaterialer. Pozzolaner som flygeaske og silikastøv er hyppig brukte tilsetningsmaterialer som kan påvirke betongens egenskaper. Glidestøp er en rask og kostnadseffektiv konstruksjonsmetode som har vært i bruk i flere tiår. Teknikken blir brukt i byggeprosjekter med høye strukturer som for eksempel heissjakter, brutårn og plattformer offshore. Metoden er enkel, men utfordrende, da glidestøp pågår døgnet rundt til ønsket konstruksjonshøyde er oppnådd. Betongen blir støpt ut lagvis i en glideform som løftes med jevne mellomrom. Når glideformen løftes blir betongen utsatt for friksjonskrefter. Blir friksjonskreftene for høye, kan skader i betongoverflaten oppstå. Denne oppgaven har som mål å undersøke hvordan mer miljøvennlig betong egner seg til bruk i glidestøp. Det blir satt fokus på tilsetningsmaterialene flygeaske og silikastøv og hvilken effekt disse tilfører betongen. Oppgaven består av en teoridel og et forsøksprogram. Teoridelen tar for seg miljøbetong og glidestøp hver for seg, mens forsøksprogrammet skal gi en indikasjon på hvordan disse fungerer sammen. Det er brukt åtte ulike betongresepter der innholdet av flygeaske varierer fra 15 til 60%. Tre av blandingene er en kombinasjon av flygeaske med 6% silikastøv. Glideriggen ved Universitetet i Stavanger blir brukt for gjennomføring av forsøkene, og aktuelle data blir bearbeidet i Matlab. Av resultatene kommer det frem at økt andel flygeaske vil forlenge hydratiseringsprosessen og dermed også medføre en forlenget avbindingstid. En lengre avbindingstid vil gi større friksjon mellom glidepanelet og betongen, noe som kan resultere i større risiko for overflateskader. Ingen av betongelementene viser tendenser til skader på overflaten, slik som forventet, noe som kan skyldes at forsøkene ble utført under kontrollerte forhold.Concrete is strong, durable, and usable, and is considered as one of the world's most widely used building materials. The material is associated with high emissions of greenhouse gases, and cement production is estimated to account for 7-8% of climate emissions worldwide. The earth's climate is changing because of increased CO2 emissions, and there is therefore a high focus on making concrete more environmental-friendly by reducing use of cement. Environmental-friendly concrete is considered as concrete where measures have been taken to reduce climate emissions, where the main focus is on replacing parts of the cement with additive materials. Pozzolans such as Fly Ash and Silica Fume are frequently used additives that can affect the properties of the concrete. Slipforming is an effective and economical construction method which has been used for decades. The technique is used in construction projects with high structures such as elevator shafts, bridge towers and offshore platforms. The method is simple, but challenging, as slipforming takes place around the clock until the desired construction height is achieved. The concrete is cast in layers in a formwork. The formwork is lifted at regular intervals, and the concrete is therefore exposed to frictional forces. If the frictional forces become too high, damage to the concrete surface can occur. This thesis aims to investigate how more environmental-friendly concrete is suitable for use in slipforming. The focus is on the additive materials Fly Ash and Silica Fume and what effect these add to the concrete. The thesis consists of a theory part and an experimental program. The theory part deals with environmental concrete and slipforming separately, while the experimental program will give an indication of how these works together. Eight different concrete recipes have been used, where the content of Fly Ash varies from 15 to 60%. Three of the mixtures are a combination of Fly Ash with 6% Silica Fume. The slipforming rig at the University of Stavanger has been used to carry out the experiments, and current data has been processed in a computer program called Matlab. The results show that an increased proportion of fly ash will prolong the hydration process and thus also lead to an extended setting time. A longer setting time will give greater friction between the slipform panel and the concrete, which can result in a higher risk of surface damage. None of the concrete elements show tendencies to damage to the surface, which may be due to that the experiments were performed under controlled conditions

Application of mathematical and machine learning models to predict differential pressure of autonomous downhole inflow control devices

Controlling reservoir fluid flow is important for maximizing petroleum production through wellbores. A major challenge that reduces the production of oil is early breakthrough of secondary fluids to the wellbore perforations. This occurs due to the low viscosity of gas and water relative to oil, and the heterogeneity of reservoir permeability. Autonomous inflow control devices represent a new self-regulating technology that helps to increase petroleum production, particularly oil, by restricting the production of unwanted fluids like gas and water into the wellbores. This study develops smart systems based on machine learning models to predict the performance of autonomous inflow control devices. Several machine learning models are evaluated including adaptive neuro fuzzy inference system, hybrid adaptive neuro-fuzzy inference system genetic algorithm, artificial neural network and support vector machine and their prediction performance is compared to that of linear regression, full quadratic regression model and the mathematical autonomous inflow control device performance model. Each model is developed to estimate the differential pressure of Equiflow autonomous inflow control devices based on ninety experimentally recorded data records. The range of equiflow autonomous inflow control device, viscosity, density and flow rate are the input variables and differential pressure is the output dependent variable of each model. The prediction accuracy of the models is assessed in terms of several standard statistical accuracy performance measures. These performance indicators confirm that the machine-learning models provide superior prediction accuracy for autonomous inflow control device differential pressure. Overall, the support vector machine achieves the most accurate predictions of all the models evaluated recording root mean square error of 0.14 Mpa and coefficient of determination of 0.98. On the other hand, the linear regression model records the lowest prediction performance, highlighting the non-linearity of the autonomous inflow control device processes.publishedVersio

Glidestøp av miljøbetong

Betong er sterkt, bestandig og anvendelig, og regnes som et av verdens mest brukte byggemateriale. Materialet er forbundet med et høyt utslipp av klimagasser, og sementenproduksjonen anslås til å stå for 7-8% av utslippene på verdensbasis. Jordas klima er i forandring som et resultat av økt CO2-utslipp, og det er derfor et høyt fokus på å gjøre betong mer miljøvennlig ved å redusere sementbruken. Miljøvennlig betong regnes som betong der det er gjort tiltak for å redusere klimagassutslippene, hvor hovedfokuset ligger på å erstatte deler av sementen med tilsetningsmaterialer. Pozzolaner som flygeaske og silikastøv er hyppig brukte tilsetningsmaterialer som kan påvirke betongens egenskaper. Glidestøp er en rask og kostnadseffektiv konstruksjonsmetode som har vært i bruk i flere tiår. Teknikken blir brukt i byggeprosjekter med høye strukturer som for eksempel heissjakter, brutårn og plattformer offshore. Metoden er enkel, men utfordrende, da glidestøp pågår døgnet rundt til ønsket konstruksjonshøyde er oppnådd. Betongen blir støpt ut lagvis i en glideform som løftes med jevne mellomrom. Når glideformen løftes blir betongen utsatt for friksjonskrefter. Blir friksjonskreftene for høye, kan skader i betongoverflaten oppstå. Denne oppgaven har som mål å undersøke hvordan mer miljøvennlig betong egner seg til bruk i glidestøp. Det blir satt fokus på tilsetningsmaterialene flygeaske og silikastøv og hvilken effekt disse tilfører betongen. Oppgaven består av en teoridel og et forsøksprogram. Teoridelen tar for seg miljøbetong og glidestøp hver for seg, mens forsøksprogrammet skal gi en indikasjon på hvordan disse fungerer sammen. Det er brukt åtte ulike betongresepter der innholdet av flygeaske varierer fra 15 til 60%. Tre av blandingene er en kombinasjon av flygeaske med 6% silikastøv. Glideriggen ved Universitetet i Stavanger blir brukt for gjennomføring av forsøkene, og aktuelle data blir bearbeidet i Matlab. Av resultatene kommer det frem at økt andel flygeaske vil forlenge hydratiseringsprosessen og dermed også medføre en forlenget avbindingstid. En lengre avbindingstid vil gi større friksjon mellom glidepanelet og betongen, noe som kan resultere i større risiko for overflateskader. Ingen av betongelementene viser tendenser til skader på overflaten, slik som forventet, noe som kan skyldes at forsøkene ble utført under kontrollerte forhold.Concrete is strong, durable, and usable, and is considered as one of the world's most widely used building materials. The material is associated with high emissions of greenhouse gases, and cement production is estimated to account for 7-8% of climate emissions worldwide. The earth's climate is changing because of increased CO2 emissions, and there is therefore a high focus on making concrete more environmental-friendly by reducing use of cement. Environmental-friendly concrete is considered as concrete where measures have been taken to reduce climate emissions, where the main focus is on replacing parts of the cement with additive materials. Pozzolans such as Fly Ash and Silica Fume are frequently used additives that can affect the properties of the concrete. Slipforming is an effective and economical construction method which has been used for decades. The technique is used in construction projects with high structures such as elevator shafts, bridge towers and offshore platforms. The method is simple, but challenging, as slipforming takes place around the clock until the desired construction height is achieved. The concrete is cast in layers in a formwork. The formwork is lifted at regular intervals, and the concrete is therefore exposed to frictional forces. If the frictional forces become too high, damage to the concrete surface can occur. This thesis aims to investigate how more environmental-friendly concrete is suitable for use in slipforming. The focus is on the additive materials Fly Ash and Silica Fume and what effect these add to the concrete. The thesis consists of a theory part and an experimental program. The theory part deals with environmental concrete and slipforming separately, while the experimental program will give an indication of how these works together. Eight different concrete recipes have been used, where the content of Fly Ash varies from 15 to 60%. Three of the mixtures are a combination of Fly Ash with 6% Silica Fume. The slipforming rig at the University of Stavanger has been used to carry out the experiments, and current data has been processed in a computer program called Matlab. The results show that an increased proportion of fly ash will prolong the hydration process and thus also lead to an extended setting time. A longer setting time will give greater friction between the slipform panel and the concrete, which can result in a higher risk of surface damage. None of the concrete elements show tendencies to damage to the surface, which may be due to that the experiments were performed under controlled conditions

Improving drilling hydraulics estimations ‑ a case study

Accurate pressure drop estimation is important for drill string and bit nozzles design and optimized fluid circulations as well as identifying the drilling problems such as bit nozzle(s) washout or plugging. In this study, the Bingham Plastic model has been modified by applying a coefficient to its turbulent pressure loss calculations. This coefficient encompasses the effects of the drill pipe tool joints and other effects in estimation of pressure losses. The range of the coefficient was determined in field applications for different hole sizes and mud types. The results showed that applying a correction coefficient of 1.08–1.12 to turbulent pressure loss equations (depending on borehole size and mud type) improves the pressure loss estimation. By applying this coefficient, the estimated pressure losses are increased to compensate the under-estimation of the Bingham Plastic model. This is considered a significant contribution to accurate calculation of borehole hydraulics and in-time detection and identification of borehole problems and reduction of invisible lost time. The findings also showed that this enhanced effect is independent of the mud type. The use of this coefficient removes the necessity of using rather complex mud rheological models such as the Herschel–Bulkley model.publishedVersio

A reassessment of the stress and natural fracture orientations from analysis of image logs in the Chinese Continental Scientific Drilling Program borehole at Donghai county, Jiangsu province, China

The Chinese Continental Scientific Drilling (CCSD) project has drilled a 5100 m deep research borehole in the Sulu ultra-high pressure (UHP) metamorphic belt, eastern China. The UHP metamorphic belt is thought to be a product of continent-continent collision and has consequently experienced very intensive structural deformation. Based on a more complete well log data set of CCSD borehole, we can have a more detailed and reliable study on the structure features of borehole wall and other rock physical properties than a previous study published in 2009. Abundant data related to borehole breakouts (BOs), drilling induced tensile fractures (DITFs) and natural fractures were collected from the image logs. The BO and DITF data indicate that the average direction of the maximum horizontal principal stress (SH) of the CCSD borehole site is about 79.2° which is consistent with the convergent direction (E-W) of the Pacific Sea Plate with respect to the Eurasian Plate. Analysis of DITFs indicated that in the case of the CCSD borehole, axial drilling induced tensile fractures (ADITFs) occur occasionally in the upper section (0–2300 m) of the borehole with low dipping angle (0–10°), while transverse drilling induced tensile fractures (TDITFs) occur significantly in the lower section (3800–5000 m) with high dipping angle (10–30°). The natural fracture distribution at depth in the metamorphic rocks of the CCSD borehole indicates that (1) the failure strength of rocks and borehole depth are two factors that affects natural fracture frequency, (2) most of the dip azimuth of natural fractures is consistent with the dip azimuth of foliations observed in the core, (3) the development of most of the natural fractures probably was dominated by the development of foliations, and both the natural fractures and foliations developed in response to the subduction and exhumation of the Sulu terrene

A Case Study on the Grid Integration of Electric Vehicles in Norway - In combination with Solar Power, Fast Charging Stations and an Electric Ferry

Norge er ledende i overgangen til elektriske kjøretøy, med 82,9% av alle nyregistrerte kjøretøy så langt i 2022 er elbiler. Dette høye tilskuddet av elbiler skaper utfordringer for nettoperatørene, ettersom dagens strømnett ikke er dimensjonert for å tåle denne store elektrifiseringen. Gjennomsnittlig belastning fra en elbil som lader hjemme er lav, og strømnettet i Norge vil tåle en relativt stor overgang til elbil. Et høyt antall el-lading samtidig i ett område kan imidlertid skape utfordringer for transformatorer og kabler i distribusjonsnettet. Ved å bruke fleksibiliteten til EVlading er det mulig å spre last belastningen utover dagen, i stedet for høy belastning i løpet av korte tidsperioder. I denne masteroppgaven er påvirkningen av elbil-lading i et moderne strømnett analysert. Det er laget tre forskjellige elbil-lade caser, for å analysere hvordan ulike former for lading kan påvirke strømnettet. Det ble laget et worst case-scenario der all lading skjer rett etter arbeidstid, 16:00- 19:00, når nettet ofte er overbelastet. De to andre lade casene som ble laget, var mer fleksible, hvor den ene hadde ladestart på tilfeldige tidstrinn gjennom hele dagen, unntatt i arbeidstiden (08.00- 16.00). Det siste tilfellet hadde en langsom ladetilnærming, der alle biler lader konstant med lav effekt gjennom hele dagen, bortsett fra arbeidstiden. Strømnettet og lade casene ble analysert ved å utføre kraftstrøms-beregninger av nettet, med ulik last behov fra de forskjellige casene, over en tidsserie. Ved hjelp av disse beregningene er det mulig å analysere kraftstrømytelsen til nettet, for eksempel lastbehov, reaktiv lastbehov og spenningsstørrelser til bussene i strømnettet. å analysere kraftstrømytelsen til et strømnett er et viktig verktøy for å bestemme strøm- og spenningskvaliteten til nettet. En høy effekt- og spenningskvalitet er avgjørende for et stabilt og pålitelig strømnett. Fra elbil-case studiene er det tydelig at utnyttelse av fleksibiliteten til EV-lading i stedet for å lade alle EV-er samtidig over en liten tidsperiode resulterer i en minimal nettpåvirkning. I et scenario med høyt belastningsbehov reduseres belastningstoppene til systemet med 6 MW fra det verste scenarioet til de fleksible ladetilfellene. Videre resulterer last reduksjonen i en økning av minimumsverdien på spenning i den svakeste bussen i strømnettet, som er hevet med 0,048 p.u. og 0,049 p.u. i de to fleksible lade casene. For ytterligere å redusere netteffekten av den høye lastkrevende elbilladingen, er tre tilleggstiltak lagt til lade casene: En solcellepark som produserer 4.67 MW på det meste, reaktiv kraft støtte fra elbiler og to hurtig lade stasjoner & en elektrisk ferge, og et batteri lagt til HDEV FCS. Tiltakene legges til alle de tre ladetilfellene, som deretter analyseres, på samme måte som ovenfor med mest fokus på spenningsytelsene. Hvert enkelt tiltak hadde en positiv innvirkning på spenningskvaliteten. En kombinasjon av tiltakene gjorde det imidlertid mulig å heve spenningskvaliteten i systemet tilstrekkelig. Den casen som hadde best ytelse, altså minst påvirkning på strømnettet, var en flat lade case med en kombinasjon av tilleggstiltakene: PV-park, støtte for reaktiv kraft og et stort batteri

Rate of penetration optimization using moving horizon estimation

Increase of drilling safety and reduction of drilling operation costs, especially improvement of drilling efficiency, are two important considerations in the oil and gas industry. The rate of penetration (ROP, alternatively called as drilling speed) is a critical drilling parameter to evaluate and improve drilling safety and efficiency. ROP estimation has an important role in drilling optimization as well as interpretation of all stages of the well life cycle. In this paper, we use a moving horizon estimation (MHE) method to estimate ROP as well as other drilling parameters. In the MHE formulation the states are estimated by a forward simulation with a pre-estimating observer. Moreover, it considers the constraints of states/outputs in the MHE problem. It is shown that the estimation error is with input-to-state stability. Furthermore, the ROP optimization (to achieve minimum drilling cost/drilling energy) concerning with the e cient hole cleaning condition and downhole environmental stability is presented. The performance of the methodology is demonstrated by one case study.publishedVersio