Methods and systems for determining reservoir properties of subterranean formations with pre-existing fractures
First Claim
1. A method for determining a reservoir transmissibility of at least one layer of a subterranean formation having preexisting fractures having a reservoir fluid comprising the steps of:
- (a) isolating the at least one layer of the subterranean formation to be tested;
(b) introducing an injection fluid into the at least one layer of the subterranean formation at an injection pressure exceeding the subterranean formation fracture pressure for an injection period;
(c) shutting in the wellbore for a shut-in period;
(d) measuring pressure falloff data from the subterranean formation during the injection period and during a subsequent shut-in period; and
(e) determining quantitatively the reservoir transmissibility of the at least one layer of the subterranean formation by analyzing the pressure falloff data with a quantitative refracture-candidate diagnostic model.
1 Assignment
0 Petitions
Accused Products
Abstract
Methods and systems are provided for evaluating subsurface earth oil and gas formations. More particularly, methods and systems are provided for determining reservoir properties such as reservoir transmissibilities and average reservoir pressures of formation layer(s) using quantitative refracture-candidate diagnostic methods. The methods herein may use pressure falloff data from the introduction of an injection fluid at a pressure above the formation fracture pressure to analyze reservoir properties. The model recognizes that a new induced fracture creates additional storage volume in the formation and that a quantitative refracture-candidate diagnostic test in a layer may exhibit variable storage during the pressure falloff, and a change in storage may be observed at hydraulic fracture closure. From the estimated formation properties, the methods may be useful for, among other things, determining whether a pre-existing fracture is damaged and evaluating the effectiveness of a previous fracturing treatment to determine whether a formation requires restimulation.
71 Citations
21 Claims
-
1. A method for determining a reservoir transmissibility of at least one layer of a subterranean formation having preexisting fractures having a reservoir fluid comprising the steps of:
-
(a) isolating the at least one layer of the subterranean formation to be tested;
(b) introducing an injection fluid into the at least one layer of the subterranean formation at an injection pressure exceeding the subterranean formation fracture pressure for an injection period;
(c) shutting in the wellbore for a shut-in period;
(d) measuring pressure falloff data from the subterranean formation during the injection period and during a subsequent shut-in period; and
(e) determining quantitatively the reservoir transmissibility of the at least one layer of the subterranean formation by analyzing the pressure falloff data with a quantitative refracture-candidate diagnostic model. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A system for determining a reservoir transmissibility of at least one layer of a subterranean formation by using variable-rate pressure falloff data from the at least one layer of the subterranean formation measured during an injection period and during a subsequent shut-in period, the system comprising:
-
a plurality of pressure sensors for measuring pressure falloff data; and
a processor operable to transform the pressure falloff data to obtain equivalent constant-rate pressures and to determine quantitatively the reservoir transmissibility of the at least one layer of the subterranean formation by analyzing the variable-rate pressure falloff data using type-curve analysis according to a quantitative refracture-candidate diagnostic model.
-
-
19. A computer program, stored on a tangible storage medium, for analyzing at least one downhole property, the program comprising executable instructions that cause a computer to:
determine quantitatively a reservoir transmissibility of the at least one layer of the subterranean formation by analyzing the variable-rate pressure falloff data with a quantitative refracture-candidate diagnostic model. - View Dependent Claims (20, 21)
Specification