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Abstract The amount of tight formations petrophysical work conducted at present in horizontal wells and the examples available in the literature are limited to only those wells that have complete data sets. This is very important. But the reality is that in the vast majority of horizontal wells the data required for detailed analyses are quite scarce. To try to alleviate this problem, a new method is presented for complete petrophysical evaluation based on information that can be extracted from drill cuttings in the absence of well logs. The cuttings data include porosity and permeability. The gamma ray (GR) and any other logs, if available, can help support the interpretation. However, the methodology is built strictly on data extracted from cuttings and can be used for horizontal, slanted and vertical wells. The method is illustrated with the use of a tight gas formation in the Deep Basin of the Western Canada Sedimentary Basin (WCSB). However, it also has direct application in the case of liquids. The method is shown to be a powerful petrophysical tool as it allows quantitative evaluation of water saturation, pore throat aperture, capillary pressure, flow units, porosity (or cementation) exponent m, true formation resistivity, distance to a water table (if present), and to distinguish the contributions from viscous and diffusion-like flow in tight gas formations. The method further allows the construction of Pickett plots without previous availability of well logs. The method assumes the existence of intervals at irreducible water saturation, which is the case of many tight formations currently under exploitation. It is concluded that drill cuttings are a powerful direct source of information that allows complete and practical evaluation of tight reservoirs where well logs are scarce. The uniqueness and practicality of this quantitative procedure is that it starts from only laboratory analysis of drill cuttings, something that has not been done in the past.
- North America > Canada > British Columbia (1.00)
- North America > Canada > Alberta (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.46)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.30)
- Oceania > Australia > Western Australia > Perth Basin (0.99)
- North America > United States > Colorado > Spindle Field (0.99)
- North America > Canada > Northwest Territories > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- (17 more...)
3D Modeling of Multistage Hydraulic Fractures and Two-Way Coupling Geomechanics - Fluid Flow Simulation of a Horizontal Well in the Nikanassin Tight Gas Formation, Western Canada Sedimentary Basin
Gonzalez, Laureano (University of Calgary) | Nasreldin, Gaisoni (Schlumberger) | Rivero, Jose (Schlumberger) | Welsh, Pete (Schlumberger) | Aguilera, Roberto (University of Calgary)
Abstract Unconventional gas is stored in extensive areas known as Basin Centered Continuous Gas Accumulations. While the estimated worldwide figures differ significantly, the consensus among the studies relating to unconventional gas resources is that the volumes are gigantic. However, the low permeability in these types of reservoirs usually results in a very low recovery factor. To help unlock these resources, this paper presents a new and more accurate way of simulating multi-stage hydraulic fracturing in horizontal wells in three dimensions (3D) using single and dual porosity reservoir models. In this approach, the geometry (not necessarily symmetric) and orientation of the multiple hydraulic fractures are driven by the prevailing stress state in the drainage volume of the horizontal well. Once the hydraulic fracturing job is accurately modeled in 3D, two-way geomechanical coupling is used to history match the produced gas from a horizontal well drilled in the Nikanassin naturally fractured tight gas formation (Western Canada Sedimentary Basin). Traditionally, the most widely used approaches have their roots in semi-analytical calculations simplifying the fracturing system to a planar feature propagating symmetrically away from a line source of injection. In contrast, the computed results presented in this study show that the incorporation of geomechanical effects gives a more realistic representation of the orientation and geometry of hydraulic fractures. Reduction in permeability of the natural and hydraulic fractures due to pressure depletion results in more realistic production predictions when compared with the case where geomechanical effects are ignored. The telling conclusion, in light of the computed results, is that the field of hydraulic fracturing provides an object lesson in the need for coupled 3D geomechanical approaches. The method presented in this paper will help to improve gas rates and recoveries from reservoirs with permeability values in the nano-Darcy scale.
- North America > Canada > British Columbia (1.00)
- North America > Canada > Alberta (1.00)
- North America > Canada > Saskatchewan > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- North America > Canada > Northwest Territories > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- North America > Canada > Manitoba > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- (3 more...)
ABSTRACT: A method is presented for determining porosity, permeability and rock mechanic properties from drill cuttings collected in horizontal wells, with a view to improve the design of multi-stage hydraulic fracturing in tight gas formations. As time is of the essence, key to the proposed approach is optimizing the design time between the moment in which the cuttings are collected and the moment in which the hydraulic fracturing job is to be performed. This is critical as the work involves experimental work with cuttings in the laboratory, analytical calculations, stimulation design with a 3D hydraulic fracturing simulator and developing of recommendations as to where to stimulate the horizontal well. Drill cuttings are powerful sources of information that have been used for several decades by well site petroleum geologists for qualitative evaluation of reservoir rocks. Additional cuttings work is carried out subsequently in the laboratory. This includes, for example, the preparation of thin sections for petrographic work and the evaluation of microfractures and slot porosity in the case to tight gas formations. Drill cuttings, however, have not been used to full advantage in the case of hydraulic fracturing jobs. This study shows that, although imperfect, drill cuttings are important direct sources of information that can help to improve results in multi-stage hydraulic fracturing jobs. In addition to qualitative analysis, cuttings can be evaluated quantitatively to provide reasonable input data for hydraulic fracturing simulators during the design stage. This becomes even more important as the amount of collected information in horizontal wells, including well logs, is rather limited in most instances, although all wells in formations with fraction of millidarcy permeability require some type of stimulation. It is concluded that information extracted from drill cuttings can be used to determine optimum locations for hydraulically fracturing of horizontal wells.
- North America > Canada > Alberta (0.71)
- North America > United States > Texas (0.46)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type (0.95)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.34)
Abstract Drill cuttings are powerful sources of information that have been used for several decades by well site petroleum geologists for qualitative evaluation of reservoir rocks. Additional cuttings work is carried subsequently in the laboratory. This includes, for example, the preparation of thin sections for petrographic work, and the evaluation of intergranular and microfracture porosity. Drill cuttings, however, have not been used to full advantage in horizontal wells drilled through tight formation. This study proposes a method for quantitative determination of porosity, permeability and rock mechanics properties from drill cuttings collected in horizontal wells. These properties are determined through a combination of laboratory, analytical and 3D simulation work. The laboratory work includes the determination of porosity and permeability in cutting samples with sizes equal to 1 mm or larger. The results are used for determining key geomechanical properties such as Poisson's ratio and Young's modulus; and the estimation of a brittleness index. The data extracted from the previous two stages are useful in 3D hydraulic fracturing simulation for designing multi-stage hydraulic fracturing in horizontal wells. Data extracted from drill cuttings are important as the amount of information collected in horizontal wells drilled thought tight formations, including cores and well logs, is rather limited in most instances. It is concluded that the proposed method provides a useful tool for evaluation of direct sources of information that are available in many cases (drill cuttings) but are rarely evaluated quantitatively. The proposed method allows improved design of multi stage-hydraulic fracturing jobs in horizontal wells.
- North America > United States (1.00)
- North America > Canada > Alberta (0.95)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.68)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.66)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Well Drilling > Drilling Fluids and Materials > Cuttings transport (1.00)
- Well Completion > Hydraulic Fracturing > Multistage fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)