Cel Provide methods and techniques allowing a better evaluation of the technical risk associated with hydraulic fracturing techniques in difficult practiical cases : reservoirs presenting natural fractures, small productive thickness, possible extension of the fracture either up into the overburden or down into the water level. As the values of the horizontal principal stresses in the reservoir and in the adjacent layers is the principal active parameter, methods will be developed for measuring these stresses. In order to evaluate the efficiency of these methods the dimensions of the fractures will be evaluated using several techniques.Minifracturation on a large size block:A new series of tests has been performed during July 1988 based on successive reopening and propagations of the fracture initiated in the block. Peak pressure and propagation pressure appear to be linear functions of the minor external stress. Influence of the major external stress is negligible. Any development of the existing fracture even at very low flow-rate and without external stresses needs a non negligible pressure. Conclusions about fracture close-up pressure are not so clear. The block was extracted and cut for analysis of the fracture geometry.This analysis is now in progress.Analysis of microfracturations and prefacturations:This analysis has been performed on 6 wells for which syntheses have been written. Different analyses are used depending on the type of test (microfracturation, prefracturation, flow-back test, fall-off test). A summary of measured stresses in overburden and reservoir layers is presented.The project is to be developed along three trends:Phase 1 :Measurement of the in-situ horizontal stresses and fracture propagation. In the problem of hydraulic fracturing the measurement of the horizontal stresses requires a precision which is not usual in the field of earth sciences. Indeed the minimum in-situ horizontal stress has to be evaluated with an absolute error inferior to one megapascal in deep or very deep geological layers. Presently, the adequate methods and/or techniques do not exist. In order to set-up these methods the following technical achievements are foreseen on each experimental site :- minifracturations at several levels in the overburden and in the reservoir rock, measurement of the downhole pressure and of other useful parameters- minifracturation in the openhole under the casing shoe- prefracturation (or fracturation with a limited amount of fluid and without propping agents) in the reservoir and with measurement of the bottomhole pressure.Phase 2:Determination of the dimensions of hydraulic fractures. In order to evaluate the dimensions of hydraulic fractures three techniques are envisaged : measurement with inclinometers of the displacements induced at the earth surface by the hydraulic fracture, detection of the acoustic emissions accompanying propagation and/or closure of the hydraulic fracture. An attempt will be made to evaluate the length and direction of the fracture with the help of the first method, the length direction and height of the fracture using the second method, the thickness of the fracture using the third method.Phase 3 :Synthesis. All the data obtained on several experimental sites will be interpreted. So will be compared the various techniques and methods experimented on sites and the existing models which simulate fracture propagation.Will be proposed:- recommended methods for the measurement of stresses and of fracture extension- recommended criteria for the selection of a numerical model offracture propagation depending on the actual mechanical and geological conditions of the hydraulic fracturing operation- feasibility criteria for hydraulic fracturing operations- recommendations for the on-site control of fracture propagation. Program(-y) ENG-HYDROCARB 2C - Programme (EEC) of support for technological development in the hydrocarbons sector, 1986-1989 Temat(-y) 1.4 - GEOPHYSICS AND PROSPECTING Zaproszenie do składania wniosków Data not available System finansowania DEM - Demonstration contracts Koordynator GERTH Wkład UE Brak danych Adres 232 AV. NAPOLEON BONAPARTE 92500 Rueil Malmaison Francja Zobacz na mapie Koszt całkowity Brak danych
