Representing the first-generation high-performance water-based drilling fluid, KCl/Polymer drilling fluidsare widely used to drill troublesome shale formations containing water-sensitive clay minerals. In additionto maintaining wellbore stability, its rheological properties also play a crucial role in enhancing overalldrilling performance. An accurate description of the rheological behavior of drilling fluids is essential inoptimizing drilling fluid hydraulics. This study evaluates traditional and novel optimization algorithmsfor the parameterization of rheological models using an extensive field rheological database of KCl/Polymer drilling fluids. An objective function based on a symmetric mean absolute percent error is used inparameterizing rheological models. Golden Section Search (GSS), Generalized Reduced Gradient (GRG),and Trust Region (TR) methods are used as new alternatives to traditional Gaussian-Newton (GN) andlinear/semi-linear regression (LR/QLR) methods. As a more statistically plausible criterion, the symmetricmean absolute percentage error is also used to measure the goodness of fit of rheological models withdatasets. It has been shown that GRG and TR algorithms outperform conventional methods in findingoptimal model parameters. The three- and four-parameter models fitted the rheological data best, with amore uniform symmetrical error distribution than the two-parameter models.
Invert emulsion drilling fluids (IEDF) are recognized as the highest-performing fluid systems available,providing invaluable benefits in drilling operations. This study uses conventional and novel algorithmsto improve the fitting ability of three and four-parameter rheological models for IEDF. Linear regression(LR), quasi-linear regression (QLR), Gold Search Section (GSS), Generalized Reduced Gradient (GRG),Trust Region (TR), and Gauss-Newton (GN) methods are employed to determine optimal rheological modelparameters. The analysis utilizes an extensive field database from five different sources. In optimizing themodel parameters, a symmetric mean absolute percentage error-based objective function is used, eliminatingthe statistical problems experienced in conventional objective functions. Average symmetric mean absolutepercentage error (SMAPE) and the number of best fits (NBF) is used for selecting the most appropriaterheological model. In the performance comparison of the models, the ranking index, which is defined as thesymmetric mean absolute error percentage and the arithmetic mean of the best fit number, is also used. Thesymmetry of the error distribution giving the balance between the overestimated and underestimated errorsis predicted by the average overestimated and underestimated symmetric percentage errors.
Turkey’s geothermal power has evolved significantly over the decade and sitting on rank 4 worldwide for the past few years with total of more than 1500 MWe installed capacity. It is known that reaching to heat source in earth’s crust and uncovering the energy consists of series of complex operations. Drilling a well is one major part of the series and contributes to the success of the project imperatively. Drilling a geothermal well has some distinct challenges, most of which are interrelated with drilling fluids. Therefore, design of drilling fluids and on-site execution play a substantial role for harnessing geothermal energy.
Fractured formations are commonly encountered while drilling carbonate reservoirs. Drilling of fractured formations usually results in lost circulation. In some cases, target zones cannot be reached due severe to lost circulation incidents.
This article presents a comparison of Power's law, Bingham plastic, Casson, Herschel-Bulkley, Unified Herschel-Bulkley, Robertson-Stiff, Gucuyener, Sisko and modified Sisko models using a rheological database of extensive real field and laboratory datasets. In this study, 778 field and laboratory shear rate/shear stress datasets collected from four different sources for oil-based (OBM) and synthetic-based (SBM) muds were evaluated. Rheological measurements were made using Couette coaxial cylinder rotational viscometer such as Fann-35 type viscometers, in the shear rate range of 5.11 to 1022 1/s.
Determining the appropriate friction factor value for calculating the frictional pressure loss of non-Newtonian fluids in a pipe is a critical task. This study aims to obtain an explicit friction factor correlation to accurately calculate the pressure losses for turbulent flow of yield pseudoplastic fluids in both smooth and rough pipes. A series of experiments are carried out with carboxymethyl cellulose (CMC) solutions using pipes of three different relative roughness. The Herschel-Bulkley model is found to be the most appropriate model to describe the yield pseudoplastic behavior of the CMC solutions used in this study.
Drilling in a lost circulation zone has long been a challenge in geothermal wells due to its strong potential for high torque and wellbore instability. Particularly in deviated, extended reach and horizontal wells, frictional forces between drill string and wellbore or casing may be high enough to interfere with running the pipe in and out of the hole. These forces may also increase the torque and the stress on drill string which may end up with severe problems like stuck pipe and lost in hole. High-temperature high-pressure (HTHP) drilling fluids design, which minimize loss rates and friction values, is critical for the success in the face of these challenging drilling practices.
This paper discusses both technical and project management aspects of drilling fluids services for deepwater and high pressure high temperature (HPHT) offshore drilling projects. The technical discussion part includes deepwater and HPHT specific fluids related concerns such as logistics, narrow drilling window, shallow hazards, gas hydrates, HPHT conditions and low temperature rheology; together with practical solutions for each of them. As some of these challenges cannot be met by only fluids itself, technologies such as managed pressure drilling (MPD), dual-gradient drilling (DGD) and use of special downhole tools are also included in the discussions.
The lost circulation is a primary consideration while drilling through fractured carbonate formations. Uncontrolled lost circulation may result in high nonproductive drilling time and cost, stuck pipe, side-tracks, blowouts and occasionally, the abandonment of expensive wells depending upon the severity of the loss. Additionally, drill solids entering the reservoir as a result of lost circulation may plug the pore throats, leading to a significant decrease in production.
Anüluste sürtünme kaynaklı basınç kayıplarının doğru olarak hesaplanması, sondaj ve kuyu tamamlama operasyonlarının kaçak, dizi sıkışması ya da daha ciddi kuyu kontrolü problemleri olmadan yapılabilmesi için gereklidir. Newtonian ve Newtonian olmayan akışkanlar kullanılarak sürtünme kaynaklı basınç kayıplarının belirlenmesi için birçok deneysel ve teorik çalışmalar yapılmıştır. Bu çalışmalarda eş merkezlilik, kullanılan akışkanın tipi, iç borunun dönmesi ya da kuyu geometrisi gibi etkenlerin sürtünme kaynaklı basınç kaybına etkileri araştırılmıştır. Buna rağmen, jeotermal kuyular için büyük öneme sahip sıcaklığın etkisi için yapılan çalışmalar yeterli sayıda değildir.
Joined the 1 GW installed capacity club in 2017, Turkey has undeniable production and potential for geothermal energy, ranking top 5 worldwide. Harnessing geothermal energy has many challenges, from planning to commercial phases. This study features the challenges, experiences and latest advances in drilling fluids utilized in geothermal well construction process in Turkey; focusing to provide a comprehensive information about drilling fluids systems and their design principles in geothermal wells in Turkey.
Accurate estimation of annular friction pressure loss is necessary to perform drilling and well completion operations without lost circulation, pipe sticking or more serious well control problems. Determination of friction pressure loss for Newtonian and non-Newtonian fluids has been investigated in several experimental and theoretical works by considering the effects of eccentricity, pipe rotation or pipe geometry. However, there is a gap in the studies about the experimental investigation of temperature effect that is important especially in geothermal wells.
The present work focuses on the stability of drill strings in vertical wellbores. The first rigorous treatment of stability of drill strings for vertical wellbores was presented by Lubinski (1950) and his equation is till most widely used in the industry. Cunha (2004) stated that since Lubinski (1950) used power series to solve differential equation governing the stability problem, and the terms of power series become very large for long drill strings, therefore, after a certain length, the calculations may lead to inaccurate results.
Pressure balance between the wellbore and formation is often quite sensitive due to narrow pore pressure and fracture pressure window. It gets more attention while drilling through fractured or vuggy rocks, which could easily attribute to downhole mud losses. Sealing the loss zone is of great concern, since it may take significant amount of resources before re-commence to drilling in a safe environment. GEOS has successfully cured a challenging thief zone with specially tailored LCM blends while drilling for a major operator.
Bu bildiride, Manisa-Alaşehir bölgesinde jeotermal kaynak arayışı hedefi ile kazılan 6 adet derin (3000+ m) kuyuda GEOS Enerji tarafından uygulanan atık azaltıcı sistemlerin uygulamaları ve sonuçları değerlendirilmiştir. Sondaj operasyonlarında oluşan sondaj atığı miktarının metre başına 0,8-1,2 ton aralığında değişim gösterdiği hesaplanmıştır.
Accurate numerical modeling of surge and swab pressures in concentric annuli is proposed. The numerical scheme is developed for the laminar flow occurring during the drillstring axial movement. The model incorporates Yield Power Law (YPL) fluids, which is a good representation of the most of the drilling fluids. A commercial computational fluid dynamics (CFD) package is used to validate the developed numerical model. Also, the mathematical model and CFD analysis are compared with the existing models from literature.
Operatör tarafından yapılan ve ortalama 3000 m. üzeri derinliğe ulaşan sondajlarda katı ve sıvı atık toplamının ortalama 2,500 m³ seviyesinde olduğu ve oluşan bu atığın sondaj süresince muhafaza edilebilmesi için en az 800 m² yüzey alanına sahip çamur havuzu ihtiyacı doğduğu görülmüştür. Tarım arazilerinin maliyeti, tarım arazisi olmayan –dağ yamacı- bölgelerde ise lokasyon inşa maliyeti ve alan sıkıntısı lokasyon büyüklüğünde kısıtlayıcı bir etken oluşturmaktadır. Sondaj boyunca çamur havuzunda biriken bu atıkların akış testi öncesi boşaltılması ve bertarafı ise bir diğer operatör problemi olarak karşımıza çıkmıştır. Oluşan sıvı atıkların bertaraf öncesi diğer lokasyonlarda bulunan çamur havuzlarında depolanması ise çamur havuzlarının önceki sondaj atığı ve akış suları ile dolu olması sebebiyle mümkün olmamıştır.
Upon the investigation related with the drilling wastes of wells of Sis Enerji Üretim A.Ş. which reach minimum of 3,000 m. depth, it was observed that minimum 800 m² of surface area is needed to store an average of 2,500 m³ waste for each drilling operation. High cost of agricultural lands and constructional difficulties on steep terrains were interrupting factors choosing suitable location. Furthermore, high disposal costs were faced as another problem to empty the mud pits which were full of cuttings and liquid wastes before flow tests.
When drilling hot wells an oil base drilling fluid systems is usually the only option for oil and gas reservoir drilling. On the other hand, for geothermal reservoir drilling, the oil based systems cannot be an option due to reservoir and reservoir characteristics. HOT-DRILL water based drilling fluid provided stability and performance in a very challenging environment.
Wellbore stability is the main issue for most of drilling area. There are many types of formation has high risk for stability. Salt formation can be the most dangerous one. An oil base drilling fluid systems is usually the only option for salt drilling, because of its stability and minimum reaction with salt. On the other hand, due to high cost, the oil based systems can not be an option. A water based super saturated salt saturated polymer drilling fluid provided stability and performance in a very challenging environment. The case has a high core recovery record among the area.
Serpentine, which is a volcanic rock, caused drilling difficulties. Wellbore cavities and pack-off are generally observed problems which causes high torques, pressure build up at SPP and even loss of the well. To minimize well stability problems, modified stresscage system; STIFF DRILL D was improved and achieved in the serpentine section. The serpentine formation is the deepest and longest one in that area as well as in Turkey.
Bu sunum, Ege bölgesi Kütahya ili Gediz grabeninde yapılan jeotermal sondajlarda karşılaşılan serpantin formasyonunun geçilmesi sırasında yaşanan kuyu stabilitesi problemlerini çözmek amacıyla yapılan saha ve laboratuvar çalışmalarını kapsamaktadır.
Volkanik bir kayaç olan serpantin, sondajı sırasında kuyu stabilitesinde büyük sıkıntılar yaşatmaktadır. Yıkılma ve dağılma problemleri kuyu içindeki stabiliteyi bozmakta, yıkılan malzemelerin taşınması ve temizliği konusunda problemler yaşanmaktadır. Bu problemler sondaj dizisinin tork almasına, basınç yükselmelerine, takım sıkışması ve kuyu kaybına kadar giden ciddi sıkıntılara yol açmaktadır.
Geos is a full-service drilling fluids company headquartered in Ankara, Turkey. We are the leader in Turkey for Drilling Fluids Systems and Waste Management Services for oil, gas and geothermal drilling industry.
We provide one of the most comprehensive range of products and services in Drilling Fluids Industry; from spud mud to non-aqueous drilling fluids, from shale shakers to drilling waste disposal services.