Gerhard Thonhauser

Gerhard Thonhauser
Montanuniversität Leoben · Petroleum Engineering

About

124
Publications
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718
Citations
Citations since 2017
33 Research Items
459 Citations
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2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100

Publications

Publications (124)
Article
A real-time in-line rheological measurement is essential in many sectors to investigate and monitor the performance of the unit, process, and transportation operations. Ultrasound velocity profiling (UVP) technique, combined with pressure differential (PD) data, is among the effective technologies for in-line rheological measurement. This paper rev...
Article
Due to the recent increase in drilling operations complexity, the frequency of undesirable downhole events occurring while drilling a well is in ascend trend leading to substantial growth in non-productive time. Consequently, overall drilling costs become sky-high, a moment in which earlier and precise detection of the downhole drilling problems be...
Conference Paper
Over the past decade, several methods and techniques have been proposed to optimize drilling hydraulic's in real-time; one of these techniques is machine learning, which has shown promising results in prediction and optimization. Nevertheless, the real-time implementation of these techniques is still challenging since most of the published work tri...
Article
This work investigates the drilling performance by reaming while drilling (RWD) using a dual-body bit and compared it with conventional drilling by a standard drilling bit. The dual-body bit consisted of a 2.45-in pilot bit located at a short distance ahead of a 2.47*3.97-in reamer. Conducting a series of drilling experiments at a simulation drilli...
Article
Full-text available
Predicting formation damage in cased-hole and open-hole completion wells is of high importance. This is especially relevant when the damage is caused by reservoir drill-in fluids hence being well-bore induced. Cake filter removal has proven to be a good approach to estimate induced damage and to evaluate drill-in fluids’ performance. We present an...
Conference Paper
Over the past decade, several models have been generated to predict Rate of Penetration (ROP) in real-time. In general, these models can be classified into two categories, model-driven (analytical models) and data-driven models (based on machine learning techniques), which is considered as cutting-edge technology in terms of predictive accuracy and...
Conference Paper
This paper presents the results of laboratory static and dynamic tests on casing-cement-rock systems exposed to axial loads under ambient conditions. A new testing method has been developed. The casing-cement-rock system mostly fails due to tension and shear stresses. In various applications such as HPHT, deep-water, (steam) injection or geothermal...
Article
Cores can be considered the ground truth only if we eliminate or minimize their damage during core cutting, tripping, and surface handling. Such damage would adversely alter their properties. An important source of core damage is during tripping, when quick decompression might cause damage because of the induced microfractures. In this paper, a sta...
Conference Paper
The digital era is upon us in the oil and gas industry, enforcing the importance of integrating this novel concept of digital transformation is mandatory to improve the overall efficiency of the drilling process. The advances in Artificial Intelligence for the industry, and the methodology of how these solutions can be implemented will be addressed...
Conference Paper
Digital transformation is a process of applying all digital technologies and tools on current workflows to be able to deliver high quality information at the right time. The digital transformation of drilling will provide an unprecedented stream of high-quality information that has never been accomplished in the industry, through the utilization of...
Conference Paper
Digital transformation is a process of applying all digital technologies on current workflows to be able to deliver high quality information at the right time. Improving well delivery time is one of the goals for applying digital transformation inside the company. The drilling performance should be reported on daily basis and all the drifting from...
Article
Guest editorial The shift toward lower oil prices in the oil and gas industry has resulted in the necessity for more wells to be drilled at lower cost, either to sustain production or to generate new, low-cost reserves. With a continued shift in demand for hydrocarbon energy sources, this development is expected to continue with an improvement goal...
Chapter
When the core barrel containing the core column reaches the surface, the inner tube should be safely handled so that the contained core undergoes the least damage (inferred from Skopec 1992, 1994; Hettema et al. 2002; Shafer 2013; Owens and Evans 2013). To achieve this, in the beginning, a systematic and careful planning is a requirement, which als...
Chapter
One of the most common coring problems particularly in critical formations is core jamming (either at the catcher or in the inner tube) and also the risk of core loss or sliding out of the inner tube during pulling out of the hole. As was already listed in Table 5.1, most of the coring challenges lead to jamming.
Chapter
One of the main challenges during coring, particularly in exploration wells, is the possibility of unidentification of the right coring point/depth. Typically, this can be noticed only at the surface using gamma-ray logging or geology study. In such cases, the retrieved core sample is already obtained from the undesired formation or interval and th...
Chapter
In the first part of this chapter, detailed specifications and information regarding the dimensions of the core samples, hole size, and working parameters corresponding to some important coring tools, which are provided by the coring providers (both in the petroleum and mining industries) are presented. In the second part of the chapter, some impor...
Chapter
To ensure reliable core analysis results, in addition to the invasion-related core damage (discussed in Chap. 7), the least possible mechanical damage should occur to the core. Mechanical core damage is defined as a permanent change in rock properties which is not reversible by restoring the rock back to in situ conditions.
Chapter
Following coring and retrieval of the core sample, knowing its exact orientation with respect to the formation bedding contributes to better understanding the geological structure of the reservoir. Knowing the structure, in turn, helps to identify the most efficient recovery methods. However, this knowledge is not conventionally available unless or...
Chapter
As mentioned in Chap. 3, conventional coring is a traditional method of taking samples from bottom-hole formations. This method is still the most commonly practiced method in the petroleum industry whereas it is almost never used in the mining industry.
Chapter
It was already discussed in Chaps. 7 and 8 that using conventional, non-pressurized coring during tripping, the core may undergo some invasion-related mechanical damage due to the fluid expulsion. This causes some loss of data and inability to recover meaningful core analysis data such as the in situ fluid saturations (inferred from Johns and Lewis...
Chapter
Fundamental coring methods fall into three main categories consisting of conventional coring, wireline continuous coring, and sidewall coring. Conventional and wireline continuous methods are applied at the time of drilling and are thus named bottomhole coring. Sidewall coring is used after drilling. These methods are introduced in this chapter (us...
Chapter
One of the basic coring objectives is obtaining core samples with least possible damage to ensure reliable core analysis results. One of the sources of damage is related to mud invasion/chemical.
Chapter
As discussed in Chap. 5, conventional coring suffers from extremely long tripping times. The whole drilling string must be pulled out of the hole before the whole coring assembly (including inner and outer tube assembly) can be run in the hole. Similarly, following the core-drilling, the coring string must be conventionally pulled out before the dr...
Chapter
There are some other coring systems, which are not in widespread use, however, they are greatly important for particular applications. These coring systems include motor coring, underbalanced coring, and coil tubing among which motor coring has greater applicability in industry. These will be explained in this chapter.
Article
One most common cause of damage of the recovered cores occurs during their fast decompression from the bottomhole to the surface. This occurs as sufficient time is not allowed for the pore fluids in the center of the core to dissipate than in the annulus. As a result, excessive pore pressure difference and stresses are induced in the core body. Thi...
Book
This book is a practical guide to downhole rock sampling and coring concepts, methods, systems, and procedures for practitioners and researchers. Its chapters are based upon years of extensive studies and research about the coring methods and via direct and continuous communication and consultation obtained from various service and operator compani...
Article
Optimizing the entire drilling process and reducing overall drilling costs, thus increasing rig productivity, is a high priority for operators and drilling contractors. Moving rigs between two locations or pads may happen at a high frequency, making the rig move a key element in overall productivity improvement. An optimization of rig move duration...
Article
Full-text available
Volumetric changes in the active drilling fluid system during drilling operation are commonly termed borehole ballooning or breathing. One of the borehole ballooning contributors is the elastic deformation of an open borehole wall. When the elastic deformation of the open borehole wall occurs, it causes a volumetric change in the active drilling fl...
Conference Paper
A deterministic method for standpipe pressure calculation in real-time using rig sensor data is presented. The main achievement is the development of a method for modeling wellbore hydraulics with satisfactory accuracy, despite lack and inaccuracy of information about the drillstring components. Exclusion of calibration makes the model more robust...
Conference Paper
Integrated planning unveils insight into a large project and all its bottlenecks for every discipline. In order to optimize utilization of facilities, optimize scheduling and its subsequent operations, an integrated planning tool was developed especially for large scale and complex shale resource projects. The best option to come up with a suitable...
Conference Paper
Coring in unconventional reservoirs with typical unconsolidated formations has introduced additional challenges requiring more innovative concepts to be developed. These requirements, economic issues of unconventional reservoirs, and also issues of conventional coring particularly in regard to excessive trip times incurred have recently led to wide...
Conference Paper
Historically Reaming While Drilling (RWD) operations have been restricted to softer formations. The objective in this study is to create a thermoporoelastic model of Mechanical Specific Energy (MSE) for RWD in order to shed important new light on the decision process how to use RWD for a specific formation as well as a recommendation for reamer-pil...
Article
Full-text available
One of the major sources of lost times in Iranian oil fields is stuck pipe which may occur due to differential sticking forces, inadequate hole cleaning and the consequent formation of cuttings beds in high angle wells, chemically active formations and inadequate mud weight leading to wellbore instability, fractured/faulted formations, and over-pre...
Article
Different researches have been developed during the past years aiming addressing challenges still faced in petroleum exploration. Rate of penetration and specific energy studies have been the main focuses in trying to boost operational efficiency. The combination of both techniques accomplished with a preoperational test (drill-rate test) may allow...
Article
Full-text available
Few analytical solutions have been published in the past decades for quantifying the ballooning volume caused by elastic deformation of an open borehole; nevertheless none of them takes into consideration the effects of permeability and thermoelasticity. This paper introduces new analytical solutions aiming at predicting a radial elastic displaceme...
Conference Paper
Pre-salt layers has long-term exploration and production possibilities, however the properties of such layers are highly challenging for exploration (i.e. these carbonate layers are highly abrasive, located deeper than 5000 m, have generally low permeability) and production (i.e. pre-salt layers are located in harsh oceanic conditions, hundreds of...
Conference Paper
Full-text available
Pre-salt basins and its exploration have become more and more frequently mentioned over the years, not just for their potential reserves, but for the implicit challenges in terms of general operations (downstream and upstream) to be faced in order to make these fields effectively commercially viable. Several research efforts aimed at to addressing...
Conference Paper
Efficiency is driving the cost for shale resource developments. Thus modeling of drilling and completion operations is key for increasing the pace of development in tough economic conditions. The objective is to develop an operational strategy that minimizes downtime on single pads, as well as to manage operations efficiently amongst multiple well...
Article
Full-text available
Several mathematical ROP models were developed in the last five decades in the petroleum industry, departing from rather simple but less reliable R-W-N (drilling rate, weight on bit, and rotary speed) formulations until the arrival to more comprehensive and complete approaches such as the Bourgoyne and Young ROP model (BYM) widely used in the petro...
Article
It has been shown that artificial neural networks (ANNs), as a method of artificial intelligence, have the potential to increase the ability of problem solving to geoscience and petroleum industry problems particularly in case of limited availability or lack of input data. ANN application has become widespread in engineering including geoscience an...
Conference Paper
Full-text available
The concept of enterprise level and standardised realtime data management solutions supporting drilling operations is rapidly gaining considerable recognition with dynamic and technology-comfortable Operators. Whether delivered physically in an Operations Centre or virtually via web browser, the business drivers are clear – when presented in an erg...
Conference Paper
High numbers of lack of hydraulic zonal isolation and occurrences of numerous high annulus pressure problems in wells in Middle East which has led to more remedial cementing and also workover rig days, has encouraged the industry to consider more efficient cement bond evaluation methods and discriminate between zonal isolation and cement bond log i...
Conference Paper
To be alerted in determining early warning signs in well control is one of the most important to wellbore safety. Careful observance and positive reaction to these signs will keep the well under control and prevent the occurrence of a well flow situation. Developing an accurate ultrasonic caliper with a special design helps the drilling engineer no...
Conference Paper
Full-text available
Recognizing the events in time series data, generated by a dynamic system, is an essential step in analyzing the behavior of the underlying system and improving its performance. In this paper a pattern-based framework is proposed for events recognition in drilling time series data. The proposed approach takes into consideration the temporality of t...
Article
Recognition of variations in borehole shape in real time drilling allows the drilling engineer to actuate appropriate counteractions to avoid costly failures, or to implement alterations in the drilling practices to optimize the shape of the borehole and thus improve the drilling efficiency. Developing a high accurate ultrasonic caliper with a spec...
Conference Paper
During the past decades the challenges involved in the petroleum exploration and production have dramatically increased. Extreme operating conditions such as highly deviated wells, deep water drilling or narrow pressure windows force the necessity for automatic and smart systems in order to successfully and safely accomplish all tasks. Solutions fo...
Article
For the development of unconventional resources enormous efforts are required. All the necessary operations cause short-term as well as long-term impacts on the environment and on the social life. In order to study those potential impacts and to find measures to keep them as low as possible, modeling contributes significantly to this goal. The here...
Article
Full-text available
Several sensor measurements collected from drilling rig during oil well drilling process. These measurements carry information not only about operational states of drilling rig but also about all high-level operations and activities performed by drilling crew. The work presented in this paper shed the light on analysis of hidden lost time in drilli...
Article
During the past decades the challenges involved in the petroleum exploration and production have dramatically increased. Extreme operating conditions such as highly deviated wells, deep water drilling or narrow pressure windows call for automated and reliable decision support systems in order to successfully and safely accomplish drilling tasks. So...
Conference Paper
Full-text available
Many natural and industrial processes such as oil well construction are composed of a sequence of recurring activities. Such processes can often be monitored via multiple sensors that record physical measurements over time. Using these measurements, it is sometimes possible to reconstruct the processes by segmenting the respective time series data...
Article
Full-text available
Recognizing patterns in time series has become a necessary machine learning task in many fields including medicine, finance, business and oil and gas industry. In this paper we propose a feature-based approach to recognize patterns in drilling time series data. Our approach consists of four phases which are: data preparation, feature extraction, fe...
Article
There is an increasing requirement for centralized analysis of drilling data to improve performance. Typically, data from service companies is transmitted from the rig to the clients Real Time Operating Centre (RTOC). A major problem is the quality of this data, which can lead to incorrect analysis and a breakdown in trust between the rig and the R...
Article
3D images of a wellbore generated in real time support drilling engineers to monitor wellbore profiles. Including the time as 4th dimension, 4D images can be used to analyze the evolution of the wellbore geometry as well as to support the drilling engineer in actuating appropriate counteractions in real time. Costly failures can be avoided more pre...
Article
An ultrasonic sensor has been developed for MWD (measurement while drilling) and LWD (logging while drilling) applications that perform real time borehole caliper measurements and also wellbore stability monitoring. The caliper determines the oval shape of the borehole with a defined accuracy and resolution, and will allow drawing conclusions on th...
Article
Characteristics of formations usually cause changes in the drilling parameters such as weight on bit and drill string rotational speed as well as drill string dynamic behavior. When the drill bit breaks up formations, some of the energy dedicated to drilling is transmitted to the drill string as axial, lateral and torsional vibrations. Although the...
Conference Paper
Vibrations are known as destructive loads and thus are leading to downhole fatigue failures, severe bottom hole assembly and bit wear and may cause wellbore instabilities. Downhole measurement of vibrations, however, can provide valuable information about downhole conditions and characteristics of the formations drilled. Uniaxial compressive streng...
Conference Paper
Drilling programs continue to push into new and more complicated environments. As a result, accurate measurement and analysis of drilling data in real time are becoming more critical by means of minimizing failure costs. The measurement of actual wellbore shape in real-time can be considered as one of the key components to detect problems such as b...
Article
With the increasing demand for energy in the last decades, the petroleum industry was forced to push the limits to levels that have never been reached before. Exploring very deep waters, drilling under varying conditions of extreme pressure and temperature and dealing with issues, which involve a new level of understanding, are challenges, which ne...
Article
Drilling programs continue to push into new and more complicated environments. As a result, accurate measurement, interpretation and analysis of drilling data in real time are becoming more critical. One of the key measurement devices for drilling, cementing and formation evaluation is the borehole caliper. An ultrasonic sensor caliper tool is ther...
Conference Paper
Full-text available
Detection of oilwell drilling operations is an important step for drilling process optimization. If drilling operations are classified accurately, detailed performance reports not only on drilling crews but also on drilling rigs can be produced. Using such reports, the management can evaluate the drilling work more precisely from performance point...
Article
Vibrations are caused by bit and drill string interaction with formations under certain drilling conditions. They are affected by different parameters such as weight on bit, rotary speed, mud properties, BHA and bit design as well as by the mechanical properties of the formations. During the actual drilling process the bit interacts with different...
Conference Paper
Full-text available
Several sensor measurements are collected from drilling rig during oil well drilling process. These measurements carry information not only about the operational states of the drilling rig but also about all higher level operations and activities performed by drilling crew. Automatic detection and classification of such drilling operations and stat...
Conference Paper
Full-text available
Time series data are ubiquitous and being generated at an unprecedented speed and volume in many fields including finance, medicine, oil and gas industry and other business domains. Many techniques have been developed to analyze time series and understand the system that produces them. In this paper we propose a hybrid approach to improve the accur...
Article
Drilling programs continue to push into new and more complicated environments. As a result, accurate measurements of drilling data in real time are becoming more critical by means of minimizing the risks as well as the costs. An ultrasonic caliper sensor is a key measurement for determining the borehole diameter in MWD and LWD tools. Important is t...
Article
The measurement of actual wellbore shape in real-time can be considered as one of the key components to detect problems such as borehole instability. Abnormal wellbore shape will allow drawing conclusions on the stress field and the impact on other sensors' responses as part of LWD measurements. Accurate wellbore caliper measurements in real-time w...
Article
A drill bit creates a hole in subsurface formations by applying weight on bit and rotary speed. The bit is the first segment of the bottom hole assembly (BHA) and the drill string which contacts formation. Today it is possible to monitor drilling parameters such as weight on bit, rotary speed of drill string, azimuthal and inclination angles of the...
Article
In order to decrease the carbon dioxide (CO2) content of gas streams to reach environmental or sales gas requirements, a series of different techniques have been established over the years. For example, in natural gas processing, aqueous amine solutions are commonly used as a washing media. A category of new fluids, ionic liquids (ILs), shows certa...
Conference Paper
Full-text available
Multivariate time series data often have a very high dimensionality. Classifying such high dimensional data poses a challenge because a vast number of features can be extracted. Furthermore, the meaning of the normally intuitive term "similar to" needs to be precisely defined. Representing the time series data effectively is an essential task for d...
Conference Paper
Full-text available
One of the major challenges in the drilling industry is the quick detection of problems that can occur during drilling a deep well due to high cost implications. These problems can occur for various reasons and can exhibit varying symptoms, which make them difficult to identify or prevent automatically. Visual Analytics has emerged as an alternativ...
Conference Paper
Full-text available
Up to very recently, the applications of machine learning in the oil & gas industry were limited to using a single machine learning technique to solve problems in-hand. As the complexity of the demanded tasks being increased, the single techniques proved insufficient. This gave rise to intelligent systems that are hybrids of several machine learnin...
Article
An ultrasonic sensor has been developed for MWD (measurement while drilling) and LWD (logging while drilling) applications that perform real time borehole caliper measurements and also wellbore stability monitoring. The caliper determines the oval shape of the borehole with a defined accuracy and resolution. These measurements are transmitted to th...
Article
Research has always been a very important part of the petroleum industry. However the increased technical requirements combined with the present environmental and safety regulations, lead to the necessity of extensive experimentation and measurements that would assist the companies in the development of new scientific methods and technologies. Obvi...
Conference Paper
Since vibration and shock loads are always known as a destructive loads while drilling a borehole and reason for tool failure, more detailed studies of vibration and dynamic behavior of drill string and bottom hole assembly to prevent any time lost and hole problem is needed to be done. To achieve these objectives, monitoring the vibration in labor...
Conference Paper
Full-text available
The use of neural networks and advanced machine learning techniques in the oil & gas industry is a growing trend in the market. Especially in drilling oil & gas wells, prediction and monitoring different drilling parameters is an essential task to prevent serious problems like "Kick", "Lost Circulation" or "Stuck Pipe" among others. The hookload re...
Conference Paper
Full-text available
Drilling an oil & gas well is always guided by the demand to prevent crises affecting technique, investment and security. To overcome uncertainties caused by lack of knowledge about geological formations during drilling, real-time sensor measurements are used to support the prediction and thus the prevention of such crises. The proposed method supp...
Article
Drill string vibration and shock loads are known as destructive loads while drilling and are the reason for tool failure, lost time and reduction in rate of penetration. Vibrations of drill strings can be effected by bit and bottom hole assembly design, interaction of bit/formation and drilling parameters. To manage vibration, however, weight on bi...