The SPE has split the former "Management & Information" technical discipline into two new technical discplines:
- Data Science & Engineering Analytics
The SPE has split the former "Management & Information" technical discipline into two new technical discplines:
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Abstract Chemical tracer is an alternative technique for hydraulic fracture diagnosis other than tiltmeter and microseismic mapping. Fracture volume is an essential parameter for stimulation optimization and production forecast. In our previous work, we proposed a simple, cost-effective method to assess the fracture volume using partitioning chemical tracer. In the hydraulic fracturing stage, a partitioning chemical tracer slug is injected along with the fracking fluid. In the created hydraulic fracture, the tracer partitions in both vapor and liquid phases and flow back in the production stage. By analyzing the tracer production data, we could estimate fracture volume and leak-off volume. This work will first investigate chemical tracer selection criteria for the purpose of fracture volume diagnosis. Tracer partition coefficient and tracer adsorption are the main considerations. Our results suggest a careful section is needed for partition coefficient, balancing the estimation accuracy and investigation area. In addition, the selected tracer should have negligible adsorption. Numerical simulation is another way to interpret tracer test. In the second part of this paper, we propose a modified Random Walk Particle Tracking (RWPT) algorithm to simulate the partitioning chemical tracer transport with multiple mobile phases. Output obtained through the RWPT is identical with analytical solution and its tracer critical breakthrough time is more accurate than the result from the finite-difference based simulations.
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 194362, “Understanding Fracturing-Fluid Distribution of an Individual Fracturing Stage From Chemical Tracer Flowback Data,” by Wei Tian and Alex Darnley, SPE, ResMetrics; Teddy Mohle, SPE, and Kyle Johns, Contango Oil and Gas; and Chris Dempsey, ResMetrics, prepared for the 2019 SPE Hydraulic Fracturing Technology Conference and Exhibition, The Woodlands, Texas, USA, 5–7 February. The paper has not been peer reviewed. This paper presents a data set involving the pumping of multiple, unique chemical tracers into a single Wolfcamp B fracture stage. The goal of the tracer test is to improve understanding of the flowback characteristics of individually tagged fluid and sand segments by adding another layer of granularity to a typical tracer-flowback report. The added intrastage-level detail can provide insights into fracture behavior in shale-reservoir stimulation by looking at individual fluid-segment tracer•recoveries. Introduction Operators have relied upon high-intensity completion designs that include a combination of high proppant volumes, increased perforation-cluster density, and smaller-mesh-size proppants. These designs aim to create a complex fracture network and increase the contact area with shale rock. They have helped operators achieve higher initial productivity and larger estimated ultimate recovery while simultaneously enabling the drilling of horizontal wells at tighter well spacing. The traditional, bi-wing fracture model seems to be scrutinized increasingly for its lack of relevance when stimulating shale reservoirs. Operators have observed greater fracture complexity when using enhanced completion designs. These designs aim to increase fracture surface area and complexity, leading to a debate regarding the merits of stimulated reservoir volume (SRV) and propped-stimulated reservoir volume, also known as effective propped volume (EPV). SRV, estimated usually from micro seismic mapping, is a rough estimate of the volume of rock that is hydraulically fractured, and is sometimes defined as the product of gross stimulated area and pay-zone thickness. EPV is a fraction of the total SRV that is supported by proppant and is capable of flowing during depletion. From a production perspective, the surface-area contact of the fractional propped SRV is more important than the gross SRV estimate. In the past, chemical tracer data have offered stage-level insights into load recovery and hydrocarbon contribution, but the data set presented in the complete paper considers individual fluid-segment data within a single fracturing stage. A few of the questions prompting this study included: Do certain fluid segments exhibit poor tracer recovery by being placed within the unpropped fraction of the SRV? Does the order of injected fracturing fluid correspond with the order in which tracer is produced? Can the residence-time calculation for each tracer be used to infer the degree of fracture complexity? As operators elect to enhance fracture complexity by increasing perforation-cluster density, using lower-viscosity-fluid systems, and pumping smaller-mesh proppants, the modeling of fracture geometry has proved difficult. In addition, varying perforation-cluster efficiency and sand-duning effects can cause fluid and proppant to be distributed nonuniformly within the fracture network.
ABSTRACT: Tracer technology can provide valuable information on reservoir and fluid flow performance. Acquiring reliable information requires good planning, designing and implementation. In earlier papers Cubillos, H. et al 1,2,3 have presented a field case study and best practices of utilisation of gas tracer technology to improve reservoir description. In the present paper this work is extended to include the importance of an integrated approach to perform successful gas and water tracer programs. This includes a clear definition of objectives and qualified evaluation of key parameters which are crucial for a successful operation such as selection of tracer types, calculation of tracer amounts, sampling program and sampling method, detection techniques, risk evaluation and environmental consideration, and data integration into reservoir management. It has been demonstrated that reliable tracer data can be obtained through careful planning, design, implementation, and monitoring. A key element of success is integration of the project team to include the disciplines of reservoir engineering, geosciences, field operations, and tracer specialists. The best practices that we employed are documented here. In the lessons learned we also review the common mistakes and bad experiences that could occur in the absence of a robust tracer design program. The importance of analytical calculations, simulation, sampling frequency, temperature stability and the recycling of tracers are also among the topics which are addressed. Application of properly designed tracer campaigns is of great importance for all operators that manage secondary recovery programs where gas or water injection is performed. The present method review will be of help to those managing or planning gas and water tracer application projects
Leong, Y.. (Maersk Oil & Gas A/S) | de Iongh, J. E. (Maersk Oil & Gas A/S) | Bähring, S.. (Danish Technological Institute) | Tuxen, A. K. (Danish Technological Institute) | Nielsen, T. B. (Danish Technological Institute)
Abstract Short-circuit connections between injectors and producers resulting from induced or natural fractures in tight chalk reservoirs can divert the injection water resulting in poor sweep efficiency and early water breakthrough in producers. The overall impact is a significant reduction in oil recovery. Curing of these connections can be achieved through the application of a chemical conformance treatment aimed at plugging off the fracture and shutting the connected zone. Knowing the volume of the fracture is essential for such a conformance treatment, since it determines the amount of conformance chemical that should be injected. If too little material is pumped, the fracture will not be effectively closed, and if too much material is pumped, there is a risk of contaminating the connected well. However, the fracture volume estimation can be challenging due to the uncertainty of the fracture geometry. Deuterium tracers offer a simple, quick and environmentally friendly method to estimate the volume of the fracture. The method was successfully employed on an injector/producer pair with a known fracture connection in the Danish North Sea. A deuterium tracer was selectively injected at a constant rate via coil tubing (CT) into the connected zone in the injector, and the producer was sampled from the wellhead. With the exception of the fracture volume, all other volumes (and therefore transit times) within the deuterium tracer injection path are known. Based on the deuterium's arrival time, the fracture transit time and therefore volume can be calculated. The use of heavy water (D2O) as a chemical tracer allows DTI to conduct the tracer operation with real-time offshore analysis of the tracer breakthrough. The results obtained were subsequently applied to adjust the injection time and volume of the cement during the operation to cement the fracture.
Tanaka, Y. (Central Research Institute of Electric Power Industry) | Uda, T. (Central Research Institute of Electric Power Industry) | Nohara, S. (Central Research Institute of Electric Power Industry) | Okamoto, S. (Central Research Institute of Electric Power Industry)
Abstract The authors have developed an equipment for in-situ tracer experiments and an evaluation method for tracer experiments. We conducted tracer experiments with the equipment for a single fracture in a rock mass at an underground research laboratory in a granite region in Japan. A cocktail of deuterium and fluorescent dye, uranine, as non-sorbing tracers and rubidium and barium as sorbing tracers, was injected into the target fracture from one borehole and recovered by pumping at another borehole. As a result, breakthrough curves of all the four tracers could be obtained successfully at the recovery borehole. And the transport properties of the target fracture, fracture aperture, dispersion length and distribution coefficients on rock matrix, could be identified through numerical analyses of the breakthrough curves. 1 Introduction High-level radioactive wastes from nuclear power plants are going to be buried deep under the ground. Radionuclides leaked from disposal facilities might be transported with groundwater to the biosphere. Therefore, in safety assessments for geological disposal of high-level radioactive wastes, we need to understand the transport properties of host rock around disposal facilities with high accuracy. In-situ tracer experiment is a highly effective means to estimate the transport properties of rock mass. Several studies for in-situ tracer experiment have been conducted with crystalline rock in European countries (Winberg et al. 2000, Alexander et al. 2009). But Japanese crystalline rock is geologically younger and generally with higher fracture-density than European one. Besides it is very difficult to use radioactive tracers on site in Japan due to a social restriction. And in crystalline rock, radionuclides migrate with groundwater flow dispersing in fractures, diffusing into rock matrix and adsorbing on fracture surfaces and rock matrix along the way. Accordingly, there are many transport parameters to be evaluated, aperture and aperture ratio of fracture, dispersion length in fracture, effective diffusivity in rock matrix and distribution coefficients on fracture surface, rock matrix and fracture-filling materials. We cannot identify all the parameters only from the results of in-situ tracer experiments.