Fracture flow capacity

The migration of iron mineral fines, primarily hematite and magnetite, is a common occurrence in portions of the Appalachian Basin. The phenomenon often occurs after well stimulation and can result in the continuing production of iron mineral fines which pose a significant disposal problem. The migration of iron mineral fines through propped fractures can substantially reduce the fracture flow capacity. Many of these are mineral fines are native to the formation and are not formed by precipitation of acid-soluble iron salts present in injection waters during or after acidi-... 

Foamed stability afreets add-etched fradure flow capacity in the same way that it affects fluid loss control. By indeasing foam stability, a substantial indease in fradure flow condudivity will occur. By indeasing the foam stability, the pattern of rock removal is more effedive without overetching the fradure face (30). Using lower quality foams, gelling the reaction phase and indeasing the viscosity of the foam achieve maximum fracture flow capacity. 

Stimulation fluid is a treatment fluid prepared for stimulation purposes, although the term most commonly is applied to matrix stimulation fluids. Most matrix stimulation fluids are acid or solvent-based, with hydrochloric acid being the most common base due to its reaction characteristics and its relative ease of control. Matrix stimulation is a process of injecting a fluid into the formation, either an acid or solvent at pressures below the fracturing pressure, to improve the production or injection flow capacity of a well. 

The concept involves the injection and detonation of a liquid chemical explosive in natural or previously induced fracture systems or the use of a pelletized explosive to enlarge and extend these fractures to provide fragmentation and interwell communication. This study is one of few known research efforts to evaluate results of detonating sheetlike layers of explosive to increase flow capacity in confined rock formations. The literature contained little information to guide the design of the experiments. Some related work, however, had been conducted by a few individuals and oil field service companies. Briefly, the earlier work resulted... 

Cubic Law will not stand, and established the following empirical formula through the flow capacity test of fractures under the different normal stress action ... 

Acids can sometimes break emulsions within the formation either by reducing the pH or by dissolving fine particles which can stabilize emulsions. Breaking the emulsion reduces fluid viscosity thus increases the fluid carrying capacity of the flow channel. Acids may be used as breakers to reduce the viscosity of acid-sensitive fracturing gels. 

Flow-Induced Chain Scission. If the chains are overstretched, that is, e increases along the plateau in Figure 2, they will eventually break 12, 13). The molecular weight of the fracture products can then be determined by the method just outlined. Thus, through our technique we can both break chains in a controlled manner and analyze the resulting fracture products within the same apparatus, this double capacity enabling a systematic study of the flow-induced chain fracture. The principal results, to be of consequence later, are as follows ... 

As indicated above, the reservoir in the vicinity of well 3H is strongly fractured and does not contain free oil. When heated, the rocks expand, closing the fissures. Air intake capacity of the bed decreases and burning front does not form. It was therefore decided to inject into well 3H some SO m of heavy crude oil. The latter was treated beforehand to remove fiorn it the gas, water, and solid impurities then it was preheated to 80°C. Following the injection, some of the oil started to flow back into the well after two days, this oil formed a column in the well, which stood 20 m high above the petroliferous horizon. 

For uniform and stable extrusion it is important to check periodically the drive system, the take-up device, and other equipment, and compare it to its original performance. If variations are excessive, all kinds of problems will develop in the extruded product. An elaborate process-control system can help, but it is best to improve stability in all facets of the extrusion line. Some examples of instabilities and problem areas include 1) non-uniform plastics flow in the hopper 2) troublesome bridging, with excessive barrel heat that melts the solidified plastic in the hopper and feed section and stops the plastic flow 3) variations in barrel heat, screw heat, screw speed, the screw power drive, die heat, die head pressure, and the take-up device 4) insufficient melting or mixing capacity 5) insufficient pressure-generating capacity 6) wear or damage of the screw or barrel 7) melt fracture/sharkskin (see Chapter 2), and so on. 

Steefel Lichtner (1994) highlighted the need to take flow geometries into account when assessing the effects of host-rock alterations. They modelled diffusive and advective transport processes along a hyperalkaline fluid-filled fracture in marl and also perpendicular to it between fracture and matrix. Dolomite dissolution was found to result in increased permeability parallel to the fracture, and diffusion was responsible for the precipitation of a calcite front in the wall rock, thus isolating the fracture physically and chemically from the rock matrix. This may reduce the effective buffering and sorption capacity of the rock. The mechanisms which affect the transport properties of a host rock are shown in this work to depend on many different factors and may be far more complex than can easily be modelled or simulated in a laboratory. 

---