Optimal drilling and fracturing sequences for placing numerous horizontal wells in tight reservoirs

Abstract

Systems and methods include a technique for drilling and fracturing wells. Geomechanical properties and in-situ stresses for the field are estimated using collected data and results from mini-fracking tests. A 3D geomechanics model for the field is generated based on 3D property model and natural fracture network. First 3D hydraulic fracturing modeling for a single well is conducted to obtain an optimum pump schedule for a target fracture length and well spacing for placing numerous horizontal wells in the field. Then 3D hydraulic fracturing modeling for the multiple wells is conducted based on a drilling-fracturing sequence configured to generate symmetric fractures and to determine an optimum pump schedule for middle wells, considering tensile stress superposition. The drilling-fracturing sequence includes initially skipping fracturing of a drilled well adjacent to a fractured well. The group of wells are drilled and fractured using the sequence.

What is claimed is: 
     
         1 . A computer-implemented method, comprising:
 estimating, using collected data and results from mini-fracking tests on previous wells, geomechanical properties for a well in a group of wells in a field, including in-situ stresses and maximum horizontal stress direction for the field;   determining a prediction for a discrete natural fracture network for the field, including predicting fracture geometries, orientations, and distributions for the group of wells;   generating a three-dimensional (3D) geomechanics model for the field based on 3D grid properties of the field and the discrete natural fracture network;   conducting 3D hydraulic fracturing modeling for fracturing a single well in the field to obtain an optimum pump schedule for a target fracture length and well spacing for placing numerous horizontal wells in the field;   conducting 3D hydraulic fracturing modeling for the group of wells based on a drilling-fracturing sequence configured to generate symmetric fractures and to determine an optimum pump schedule for middle wells in the group of wells considering tensile stress superposition, wherein the drilling-fracturing sequence includes initially skipping fracturing of a drilled well adjacent to a fractured well; and   drilling and fracturing the group of wells using the drilling-fracturing sequence.   
     
     
         2 . The computer-implemented method of  claim 1 , further comprising:
 collecting data for the well, including collecting drilling reports, well surveys, formation tops, and wells logs.   
     
     
         3 . The computer-implemented method of  claim 1 , further comprising:
 performing image log processing for natural fracture orientations, fracture intensity, and for maximum horizontal stress orientation for the field.   
     
     
         4 . The computer-implemented method of  claim 1 , wherein the 3D hydraulic fracturing modeling considers an injection volume for the single well. 
     
     
         5 . The computer-implemented method of  claim 1 , wherein a fracturing order for the group of wells is different from a well numbering for the group of wells. 
     
     
         6 . The computer-implemented method of  claim 1 , wherein an injection fluid volume for a middle well drilled last in a pad is reduced by a variable α. 
     
     
         7 . The computer-implemented method of  claim 6 , wherein the variable α is a percentage reduction of the injection fluid volume for a first well from a pad. 
     
     
         8 . The computer-implemented method of  claim 7 , wherein the injection fluid volume for a last well in the pad is given by (1−α)V, wherein α is a value in a range of 0.1 to 0.3, and wherein V is a volume of injection fluid for the first well in the pad. 
     
     
         9 . A computer-implemented system, comprising:
 one or more processors; and   a non-transitory computer-readable storage medium coupled to the one or more processors and storing programming instructions for execution by the one or more processors, the programming instructions instructing the one or more processors to perform operations comprising:
 estimating, using collected data and results from mini-fracking tests on previous wells, geomechanical properties for a well in a group of wells in a field, including in-situ stresses and maximum horizontal stress direction for the field; 
 determining a prediction for a discrete natural fracture network for the field, including predicting fracture geometries, orientations, and distributions for the group of wells; 
 generating a three-dimensional (3D) geomechanics model for the field based on 3D grid properties of the field and the discrete natural fracture network; 
 conducting 3D hydraulic fracturing modeling for fracturing a single well in the field to obtain an optimum pump schedule for a target fracture length and well spacing for placing numerous horizontal wells in the field; 
 conducting 3D hydraulic fracturing modeling for the group of wells based on a drilling-fracturing sequence configured to generate symmetric fractures and to determine an optimum pump schedule for middle wells in the group of wells considering tensile stress superposition, wherein the drilling-fracturing sequence includes initially skipping fracturing of a drilled well adjacent to a fractured well; and 
 drilling and fracturing the group of wells using the drilling-fracturing sequence. 
   
     
     
         10 . The computer-implemented system of  claim 9 , the operations further comprising:
 collecting data for the well, including collecting drilling reports, well surveys, formation tops, and wells logs.   
     
     
         11 . The computer-implemented system of  claim 9 , the operations further comprising:
 performing image log processing for natural fracture orientations, fracture intensity, and for maximum horizontal stress orientation for the field.   
     
     
         12 . The computer-implemented system of  claim 9 , wherein the 3D hydraulic fracturing modeling considers an injection volume for the single well. 
     
     
         13 . The computer-implemented system of  claim 9 , wherein a fracturing order for the group of wells is different from a well numbering for the group of wells. 
     
     
         14 . The computer-implemented system of  claim 9 , wherein an injection fluid volume for a middle well drilled last in a pad is reduced by a variable α. 
     
     
         15 . The computer-implemented system of  claim 14 , wherein the variable α is a percentage reduction of the injection fluid volume for a first well from a pad.