This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 155892, "One New Needle Technology of Remote Intersection Between Two Wells and Application in Chinese Coalbed-Methane Basin," by Tian Zhonglan, SPE, Shen Ruichen, and Qiao Lei, Research Institute of Drilling Engineering, CNPC, prepared for the 2012 IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, Tianjin, China, 9-11 July. The paper has not been peer reviewed.
Micro seismic data and coring studies suggest that hydraulic fractures interact heavily with natural fractures creating complex fracture networks in naturally fractured reservoirs such as the Barnett shale, the Eagle Ford shale, and the Marcellus shale. However, since direct observations of subsurface hydraulic fracture geometries are incomplete or nonexistent, we look to properly scaled experimental research and computer modeling based on realistic assumptions to help us understand fracture intersection geometries. Most experimental analysis of this problem has focused on natural fractures with frictional interfaces. However, core observations from the Barnett and other shale plays suggest that natural fractures are largely cemented. To examine hydraulic fracture interactions with cemented natural fractures, we performed 9 hydraulic fracturing experiments in gypsum cement blocks that contained embedded planar glass, sandstone, and plaster discontinuities which acted as proxies for cemented natural fractures.
There were three main fracture intersection geometries observed in our experimental program. 1) A hydraulic fracture is diverted into a different propagation path(s) by a natural fracture. 2) A taller hydraulic fracture bypasses a shorter natural fracture by propagating around it via height growth while also separating the weakly bonded interface between the natural fracture and the host rock. 3) A hydraulic fracture bypasses a natural fracture and also diverts down it to form separate fractures. The three main factors that seemed to have the strongest influence on fracture intersection geometry were the angle of intersection, the ratio of hydraulic fracture height to natural fracture height, and the differential stress.
Simply put, the most significant finding of this research is that fracture intersection geometries are complex. Our results show that bypass, separation of weakly bonded interfaces, diversion, and mixed mode propagation are likely in hydraulic fracture intersections with cemented natural fractures. The impact of this finding is that we need fully 3D computer models capable of accounting for bypass and mixed mode I-III fracture propagation in order to realistically simulate subsurface hydraulic fracture geometries.
To address the unfavorable thermal recovery factor of abundant ultra-viscous oil resources using vertical and horizontal wells in Xinjiang's Fengcheng Oilfield, Steam-Assisted Gravity Drainage (SAGD) parallel horizontal wells were experimentally
drilled in block A in 2008, which delivered on 100% encountering rate of oil formations and controlled the wellbore trajectories within the design. However, the production witnessed difficulties in setting oil well pumps and insufficient submergence depth. To tackle this issue, a drilling test to connect one of the SAGD parallel horizontal wells and the vertical well was performed. With several pioneering technologies in China, the test succeeded and created a new technological approach for the development of ultra-viscous oil in Xinjiang Oilfield.
This paper describes the principle, process, and equipment of the drilling technology in the test, analyzes the field results of the section milling of large size casing, under-reaming of the intersection interval, intersection between a horizontal well and
a vertical well, and down-hole gravel packing, and presents comments on the field application and future development of the technology.
Keshavarzi, R. (Young Researchers Club, Science and Research Branch, Islamic Azad University) | Mohammadi, S. (School of Civil Engineering, University of Tehran) | Bayesteh, H. (School of Civil Engineering, University of Tehran)
Ben, Y. (Engineering Computation Center, Graduate University of Chinese Academy of Science) | Xue, J. (Engineering Computation Center, Graduate University of Chinese Academy of Science) | Miao, Q. (Engineering Computation Center, Graduate University of Chinese Academy of Science) | Wang, Y. (Engineering Computation Center, Graduate University of Chinese Academy of Science) | Shi, G.-H. (Engineering Computation Center, Graduate University of Chinese Academy of Science)
Bruines, P. A. (Obayashi Corporation) | Tanaka, T. (Obayashi Corporation) | Koyama, T. (Kyoto University) | Kishi, H. (Japan Atomic Energy Agency (JAEA)) | Nakanishi, T. (Japan Atomic Energy Agency (JAEA)) | Ohnishi, Y. (Kyoto University)
The new challenges of the oil exploration focused to the location in closed traps against faults in deep waters. The methodology has been developed for the juxtaposition studies by faults in structural traps that it analyzes the sealed surface, which is like an evaluation technique that quantifies of efficient way, the exploratory risk related with the sealed and the hierarchy of the prospective objectives in an opportune way speeding up the answer capacity for the taking of decisions that imply a high consumption of time and money. This summary synthesizes the method for the construction of the Allan's diagrams of juxtaposition. It consist of using computational tools that optimize the times of elaboration. The work flow has been directed in the realization of the juxtaposition (2D/3D) diagrams that it allows to evaluate the efficiency of the lateral sealed in traps against fault segment and obtaining of hydrocarbon new wells. To determine the capacity of sealed for the faults the seismic interpretation it is needed in depth of the roof-ceiling horizons, as well as the behavior of the segments of faults. Later on, it is carried out the seismic mapping of each geologic element to analyze. The principal stage of the methodology is the obtaining by means of an operation vector subtraction of the intersections of the objective horizon so much of the roof block and the ceiling block on the fault surface in the setting. Once certain, the vertical component of the fault jump for each one of the exploratory objectives. It proceeds to elaborate Allan's (2D) diagram in a profile made
up of the integration of the intersections of all the objectives for each contour of fault surface. Finally, It spreads in perspective the geometry 3D of each fault plan with their intersections type and their impact in juxtaposition. This method has been proven with success in the hydrocarbon locations on deep waters of area the Region Marina from Gulf of Mexico.