Browsing by Subject "horizontal wells"

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Access status: Open Access ,
Analysis of production data from hydraulically fractured horizontal wells in Marcellus Shale
(2013) Aminian, Khashayar; Ameri, Samuel
Unconventional reservoirs play an enormous role in hydrocarbon production in the United States. Marcellus Shale, a Devonian black shale found in the Appalachian Basin, has shown notable promise in the past few years. Shale is a complicated, naturally fractured reservoir with ultra-low matrix permeability. The gas is stored in the limited pore space of these rocks and a sizeable fraction of the gas in place may be adsorbed on the organic material. Shale gas reservoirs differ from conventional reservoirs in that massive stimulation treatments are required to achieve economic production. Horizontal wells are the most effective in providing access to the formation to perform multi-stage hydraulic fracturing treatments. The limited field experience with multiple hydraulic fractures in horizontal wells completed in Marcellus Shale indicates that significant increase in initial production can be achieved as the number of hydraulic fractures is increased. However, the production performance, particularly over longer time periods, is not well established. The objective of this study was to investigate the long term production performance of multiply fractured horizontal wells completed in Marcellus Shale. Historical production data and stimulation treatment information have been collected and analyzed for a number of horizontal wells both in West Virginia and Pennsylvania. A commercial reservoir simulator which accounts both for dual porosity behavior and the adsorbed gas was utilized to history match the production performance. Based on the results of the history matching, the long term production performances of the multiply fractured horizontal wells were predicted. The results were then utilized to investigate the production decline behavior of Marcellus Shale horizontal wells. A number of conventional as well as shale specific production decline models were considered in these investigations. The results indicated the presence of different flow periods. The hydraulic fractures appear to dominate the early production performance which is characterized by linear flow. Gas desorption appears to impact on production decline behavior during the intermediate period. The late production is influenced by the reservoir boundaries and is controlled by natural fracture properties. A single decline model often cannot predict the entire production behavior and conventional decline analysis based on the early production data can lead to significant over-prediction of the future production rates or reserves. The results of this study can be utilized as guideline to investigate the feasibility horizontal wells with multiple hydraulic fractures and optimize the production from the shale formation.
Access status: Open Access ,
Analysis of the use of a down-hole mechanical cleaning device for efficient wellbore cleaning
(2007) Qureshi, Ali; Miska, Stefan; Miska, Włodzimierz
Field evidence indicates that in highly deviated and horizontal wells, cuttings tend to accumulate on the lower side of the annulus under the influence of gravity and eventually may form a non moving bed. This leads to considerable increase in equivalent circulating density (ECD) and drag/torque as well may result in a differential pipe sticking and wellbore stability problems. A good control of drilling fluid rhelogical properties, flow rate and drillpipe rotational speed may not be sufficient in some instances. Also, the commonly used techniques of circulation at high flow rates, using sweeps of high/low viscosity and high density may not be possible and, at times, prove to be ineffective. To overcome this difficulty, a down hole cleaning subs (mechanical cleaning devices - MCDs) are incorporated in the drill string to agitates the cuttings bed by bringing the cuttings into suspension for subsequent carrying out by the drilling fluid to the surface. These devices are furnished with "blades" which produce the desired hydrodynamic effects as the drill string is rotated and helps to dislodge the cuttings from the bed. The hole cleaning is thus governed primarily by the agitation created by the device, the rheological properties of the mud and the drilling fluid flow rate. Taking these factors into account, a study was conducted at Tulsa University Drilling Research Projects' (TUDRP) large scale wellbore simulator to experimentally determine the cleaning efficiency of a Mechanical Cleaning Device (MCD). From the database generated through the experiments, correlations were obtained by performing regression modeling to extend the results to field applications. These correlations are based on dimensionless parameters and predict reasonably accurately the in-situ cuttings concentration when the MCD is installed in the drill string. The results are useful for designing of the optimal hydraulic program for extended reach, high angle and horizontal wells.
Access status: Open Access ,
Experimental study of hydraulic sweeps in horizontal wells
(2010) Nguyen, Thanh N.; Miska, Stefan; Yu, Mengjiao; Takach, Nicholas E.; Ahmed, Ramdan
Drilling fluid sweeps are commonly run in the field to help clean the borehole of cuttings that have not been removed with normal drilling fluid circulation, especially in high angle or extended reach wells where efficient hole cleaning is more difficult to maintain. This study focuses on the use of conventional and enhanced sweeps in horizontal well bores. Not much information pertaining to the use of drilling fluid sweeps is available in the literature. Furthermore, there has been a lack of agreement as to which types of sweep fluids are most effective. Conventional sweeps most often include high viscosity fluids, high density fluids or a combination of both. In addition to conventional sweep fluids, an attempt was made to use enhanced sweep fluids, in which surfactants are used to attach cuttings to oil droplets that are intentionally introduced to the drilling fluid system. Because of their low density, oil droplets can have the ability to keep cuttings particles in suspension. The use of oil droplets is a new concept in cleaning horizontal and deviated wellbores. This work focuses on experimental analysis of sweep fluids with the goal of quantifying the sweep "efficiency". A small-scale sweep loop (SSL) was mainly used to conduct sweep experiments. Moreover, some experiments were carried out in a field-scale flow loop that operates at low-pressure ambient temperature (LPAT) conditions. Results show that pipe rotation plays a very important role in improving hole cleaning. Particularly, the improvement is substantial with high-viscosity fluids. The rotation of pipe has agitation effect that forces the cuttings particles into the main flow and facilitates the removal process. As anticipated, increasing the flow rate enhances the sweep efficiency or cuttings removal regardless of the drillpipe rotation. Furthermore, the study suggests that with a more rigorous evaluation of sweep efficiency, one can objectively determine the type and frequency of drilling sweep. The results of this study are useful for selection of the optimal sweep fluid.
Access status: Open Access ,
Model of drag and torque for casing running in extended reach and horizontal wells
(2008) Miska, Stefan; Yu, Mengjiao; Yi, Zhang; Miska, Włodzimierz
Application of extended reach and horizontal wells for offshore and onshore exploration and production purposes has been continuously increasing over the last decade. To reach the desired targets many of these wells are planed to have there dimensional complex well trajectories. Field experience indicate that running casing into wells with high horizontal departure and complex trajectories is frequently associated with many problems resulting in high cost of operations. In some instances the high pushing force resulted in casing buckling and the casing has not reach the planned depth. To reduce the pushing force one can rotate casing but that requires application of a sufficiently high torque. In any case accurate calculations of drag forces and torque are needed to evaluate casing mechanical integrity and technical feasibility of the casing running operation during planning and drilling stage of well development. In this paper we show the development of an improved characterization of wellbore trajectory by including the wellbore torsion in addition to the traditional wellbore curvature (dogleg severity). We also show the development of 3D drag and torque model that makes allowance for wellbore curvature, torsion, pipe bending stiffness and its weight in fluid. Finally, the paper is furnished with practical examples that show the application of the developed mathematical model. The proposed model is useful for practical design applications such as optimization of a well trajectory, calculating loads on casing and better understanding of field records and observations.
Access status: Restricted ,
Technologie szczelinowań pokładów węglowych otworami poziomymi wierconymi z powierzchni
(Data obrony: 2016-10-05) Cieślak, Katarzyna
Wydział Wiertnictwa, Nafty i Gazu
Access status: Open Access ,
Wykorzystanie wyników symulacji komputerowej do oceny efektywności udostępnienia złoża ropy naftowej za pomocą otworów horyzontalnych
(2008) Stopa, Jerzy; Wojnarowski, Paweł; Rychlicki, Stanisław
Presently horizontal wells are used worldwide both for new wells and for reconstructing the already existing ones. As compared to the vertical wells, horizontal wells offer a number of optimization possibilities as far as economic and technological parameters are concerned. The potential benefits and their utilization commonly fall into two categories. The first one creates possibilities of increasing reserves and/or enhanced production. The other one enables lowering the cost of the production process. Literature examples of application mainly refer to reservoirs having good reservoir parameters, and enabling obtaining very high yields. The results presented in this paper are comparative results of a number of computer simulations made for one of the low-permeability Polish fields. The results, presented in the form of yield forecasts in time, may be the basis of evaluation of profitability of such wells in small fields with weak reservoir parameters.