Ultra-deepwater reservoirs are important non-conventional reservoirs that hold the potential to produce billions of barrels of hydrocarbons but present major challenges. Hydraulic fracturing or frac-packing high permeability reservoirs is different from the conventional hydraulic fracturing technology used in low permeability formations. While the main purpose of the conventional technique is to create a long, highly conductive path, frac-packing on the other hand is used predominantly to get past near wellbore formation damage, control sand production and reduce near wellbore pressure drop. Ultra-deepwater reservoirs are usually high temperature and high pressure with high permeabilities. Frac-packing these types of wells requires short fractures packed with high proppant concentrations. Understanding the behavior of the fracture fluid and proppant is critical to pump such a job successfully and to ensure long term productivity from the fracture. A series of laboratory experiments have been conducted to research the different problems resulting from high temperature and pressure which negatively affect conductivity. Unlike conventional long-term conductivity measurements, we placed the proppant into the fracture and pumped fracture fluid through it and then measured conductivity by pumping oil to represent true reservoir conditions. Proppant performance and fracture fluids clean-up during production were examined. High strength proppant is ideal for deep fracture stimulations and in this study different proppant loadings at different stresses were tested to measure the impact of crushing and embedment on conductivity. The preliminary test results indicated that oil at reservoir conditions does improve clean-up of fracture fluid left back in the proppant pack. Increasing the proppant concentration in the fracture showed higher conductivity values even at high closure stress. The increase in effective closure stress with high temperature yielded significant loss in conductivity values as compared to those obtained from industry tests.

No description available.

No description available.

Low-permeability gas wells often produce less than predicted after a fracture treatment. One of the reasons for this is that fracture lengths calculated after stimulation are often less than designed lengths. While actual fracture lengths may be shorter due to fracture growth out of zone, improper proppant settling, or proppant flowback, short calculated fracture lengths can also result from incorrect analysis techniques. It is known that fracturing fluid that remains in the fracture and formation after a hydraulic fracture treatment can decrease the productivity of a gas well by reducing the relative permeability to gas in the region invaded by this fluid. However, the relationships between fracture fluid cleanup, effective fracture length, and well productivity are not fully understood. In this work I used reservoir simulation to determine the relationship between fracture conductivity, fracture fluid production, effective fracture length, and well productivity. I simulated water saturation and pressure profiles around a propped fracture, tracked gas production along the length of the propped fracture, and quantified the effective fracture length (i.e., the fracture length under single-phase flow conditions that gives similar performance as for multiphase flow conditions), the "cleanup" fracture length (i.e., the fracture length corresponding to 90% cumulative gas flow rate into the fracture), and the "apparent" fracture length (i.e., the fracture length where the ratio of multiphase to single-phase gas entry rate profiles is unity). This study shows that the proppant pack is generally cleaned up and the cleanup lengths are close to designed lengths in relatively short times. Although gas is entering along entire fracture, fracturing fluid remains in the formation near the fracture. The water saturation distribution affects the gas entry rate profile, which determines the effective fracture length. Subtle changes in the gas rate entry profile can result in significant changes in effective fracture length. The results I derived from this work are consistent with prior work, namely that greater fracture conductivity results in more effective well cleanup and longer effective fracture lengths versus time. This study provides better explanation of mechanisms that affect fracturing fluid cleanup, effective fracture length, and well productivity than previous work.

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 63-64.

Thesis (Ph. D.) Oregon Graduate Center, 1985.

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An apparatus was developed to measure the conductance change of electrolytes in the presence of high electric fields to a high degree of accuracy, end is described herein. The apparatus employs square wave pulse excitation to a special conductivity bridge, and permits direct observation of pulse shape on a high speed oscilloscope, as well as separate compensation of resistive and capacitive unbalance. With this apparatus, the high-field electric conductances of several solutions of biologically interesting substances were investigated and classified. The substances investigated, together with the observed increment in electric conductance at a field strength of 10⁵ volts per cm., are listed: 1. glutamine (1.25 x 10⁻⁴M), 0.56% 2. 1 (﹢) arginine monhydrochloride (2.0x10⁻⁴M), 0.48% 3. acetic acid (3.75 x 10⁻⁴M), 4.6% 4. p-amino benzoic acid (5 x 10⁻³M), 5.5% 5. sulfanilic acid (6.55 X 10⁻⁵M), 1.4% 6. 1 (﹢) glutamic acid (1.22 x 10⁻³M), 2.6% 7. glycine (0.61 M), 1.9% 8. protamine sulfate (7.9 x 10⁻⁵g/cc.) 40% 9. agar (3 x 10⁻⁴ g/cc), 37% Some of the observed results have been compared with those obtained by other methods, while the remaining substances have not been previously reported. The results were discussed in the light of available theoretical information on the high-field conductance effect in various types of electrolytes. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The superconducting state is described in terms of the electronic plasma in interaction with the electromagnetic potentials. The interaction of the plasma with itself and with the latice, is represented by a potential energy determined such that the equations of motion are self-consistent. The resulting non-linear field equations are solved in the linear approximation. There exist four independent modes of vibration of the field variables corresponding to the plasma oscillations, and one longitudinal and two transverse oscillations of the electromagnetic potentials. The contribution of these modes to the specific heat is discussed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The cell constant of a direct current conductivity cell was measured using as a standard 0.1M and 0.01M potassium chloride solutions and specific conductivity data obtained by G. Jones and M. Prendergast. The results obtained for either of the solutions were exact to within one or two parts in ten thousand, but a difference of 0.6% existed between the two cell constant values. In order to investigate more exactly the nature of this variation, other concentrations were measured using as a standard the data obtained by T. Shedlovsky, A.S. Brown, and D.A. Maclnness. Certain factors in the design of a direct current cell have been considered and suggestions for future work offered. Studies have been made of the anodic properties of strained copper wire in the cell Cu (strained) ⃒ CuSO₄ ⃒ Cu (normal). Two copper wires were immersed in copper sulphate solution. Weights were added to one of these and the potential difference measured potentiometrically or with a vacuum tube volt-meter. The results obtained show that (1) the relaxation of this potential is approximately exponential, (2) very little potential is developed until a critical strain is applied, (3) after a certain strain has been applied the peak potential developed becomes constant with increasing strain, (4) the magnitude of the effect is dependant on the concentration of the solution, (5) the magnitude and direction (anodic or cathodic) of the potential is dependant upon the components of the electrolyte. / Science, Faculty of / Chemistry, Department of / Graduate