Methods and systems for estimation of formation fluid properties

Abstract

Methods and systems are disclosed herein. A method may include obtaining a well log of a well and obtaining a first fluid sample at a first one of the plurality of depths within the well. The method may include obtaining a second fluid sample at a second one of the plurality of depths within the well. The method may include determining a first fluid property from the first fluid sample and a second fluid property from the second fluid sample. The method may include determining a transform based on the first fluid property, the second fluid property, and the well log data. The method may include applying the transform to the well log data at a third one of the plurality of depths within the well yielding a first predicted fluid property. The method may include determining a subsurface development plan based on the first predicted fluid property.

What is claimed is: 
     
         1 . A method for predicting a fluid property, the method comprising:
 obtaining, using a logging system, a well log of a well,   wherein the well log comprises well log data at each of a plurality of depths within the well;   obtaining, using a fluid retrieval system, a first fluid sample at a first one of the plurality of depths within the well;   obtaining, using the fluid retrieval system, a second fluid sample at a second one of the plurality of depths within the well;   determining a first fluid property from the first fluid sample;   determining a second fluid property from the second fluid sample;   determining a transform based on the first fluid property, the second fluid property, and the well log data at both the first one of the plurality of depths and the second one of the plurality of depths;   applying the transform to the well log data at a third one of the plurality of depths within the well yielding a first predicted fluid property; and   determining a subsurface development plan based on the first predicted fluid property.   
     
     
         2 . The method of  claim 1 , wherein obtaining the well log comprises obtaining a sonic well log, and wherein the well log data comprises sonic well log data. 
     
     
         3 . The method of  claim 1 , wherein the first fluid property comprises a first American Petroleum Institute (API) gravity, and wherein the second fluid property comprises a second API gravity. 
     
     
         4 . The method of  claim 1 , wherein determining the transform comprises cross-correlating the first fluid property and the second fluid property with the well log data at both the first one of the plurality of depths and the second one of the plurality of depths yielding a fluid data cross-correlation. 
     
     
         5 . The method of  claim 4 , further comprises fitting a polynomial to the fluid data cross-correlation. 
     
     
         6 . The method of  claim 5 , wherein applying the transform comprises applying a non-linear transform based on fitting the polynomial. 
     
     
         7 . The method of  claim 1 , wherein determining the subsurface development plan comprises:
 designing, using a stimulation planning system, a stimulation plan based on the first predicted fluid property; and   stimulating, using a hydraulic fracturing system, a formation around the well based on the stimulation plan.   
     
     
         8 . The method of  claim 1 , further comprising:
 determining, using a fluid property analysis system, a reservoir fluid window based on the first predicted fluid property, wherein the reservoir fluid window comprises an oil window and a gas window.   
     
     
         9 . The method of  claim 1 , further comprising:
 obtaining, using a seismic data acquisition system, seismic data from a geographical region that includes the well;   determining, using a subsurface processing system, a velocity model based on the seismic data at a fourth location, wherein the fourth location is a distance from the well within a formation; and   applying the transform to the velocity model yielding a second predicted fluid property at the fourth location.   
     
     
         10 . The method of  claim 9 , further comprising:
 designing, using a well planning system, a borehole drilling plan based on the second predicted fluid property; and   drilling, using a drilling system, a borehole based on the borehole drilling plan.   
     
     
         11 . A method for predicting a fluid property, the method comprising:
 obtaining, using a logging system, a well log of a well, wherein the well log comprises well log data at each of a plurality of depths within the well;   obtaining, using a fluid retrieval system, a first fluid sample at a first one of the plurality of depths within the well;   obtaining, using the fluid retrieval system, a second fluid sample at a second one of the plurality of depths within the well;   determining a first fluid property from the first fluid sample;   determining a second fluid property from the second fluid sample;   determining a transform based on the first fluid property, the second fluid property, and the well log data at both the first one of the plurality of depths and the second one of the plurality of depths;   applying the transform to the well log data at a third location yielding a first predicted fluid property,   wherein the third location comprises a third one of the plurality of depths within the well;   determining a subsurface development plan based on the first predicted fluid property;   obtaining, using a seismic data acquisition system, seismic data from a geographical region that includes the well;   determining, using a subsurface processing system, a velocity model based on the seismic data at a fourth location, wherein the fourth location is a distance from the well within a formation;   applying the transform to the velocity model yielding a second predicted fluid property at the fourth location;   determining, using a fluid property analysis system, a reservoir fluid window based on the first predicted fluid property and the second predicted fluid property,   wherein the reservoir fluid window comprises an oil window and a gas window;   designing, using a well planning system, a borehole drilling plan based on the reservoir fluid window; and   drilling, using a drilling system, a borehole based on the borehole drilling plan.   
     
     
         12 . A system for estimating a fluid property, the system comprising:
 a logging system comprising a logging tool configured to obtain a well log of a well,   wherein the well log comprises well log data at each of a plurality of depths within the well;   a fluid retrieval system configured to obtain a first fluid sample at a first one of the plurality of depths and a second fluid sample at a second one of the plurality of depths;   a fluid property analysis system configured to:
 determine a first fluid property from the first fluid sample, 
 determine a second fluid property from the second fluid sample, 
 determine a transform based on the first fluid property, the second fluid property, and the well log data at both the first one of the plurality of depths and the second one of the plurality of depths, and 
 apply the transform to the well log data at a third one of the plurality of depths within the well yielding a first predicted fluid property; and 
   a subsurface development planning system configured to determine a subsurface development plan based on the first predicted fluid property.   
     
     
         13 . The system of  claim 12 , wherein the well log comprises a sonic well log and wherein the well log data comprises sonic well log data. 
     
     
         14 . The system of  claim 12 , wherein the fluid property analysis system is further configured to cross-correlate the first fluid property and the second fluid property with the well log data at both the first one of the plurality of depths and the second one of the plurality of depths yielding a fluid data cross-correlation. 
     
     
         15 . The system of  claim 14 , wherein the fluid property analysis system is further configured to fit a polynomial to the fluid data cross-correlation. 
     
     
         16 . The system of  claim 15 , wherein applying the transform comprises applying a non-linear transform based on fitting the polynomial. 
     
     
         17 . The system of  claim 12 , further comprising:
 a stimulation planning system configured to design a stimulation plan based on the first predicted fluid property; and   a hydraulic fracturing system configured to stimulate a formation around the well based on the stimulation plan.   
     
     
         18 . The system of  claim 12 , wherein the fluid property analysis system is further configured to determine a reservoir fluid window based on the first predicted fluid property, wherein the reservoir fluid window comprises an oil window and a gas window. 
     
     
         19 . The system of  claim 12 , further comprising:
 a seismic data acquisition system configured to obtain seismic data from a geographical region that includes the well;   a subsurface processing system configured to determine a velocity model based on the seismic data at a fourth location, wherein the fourth location is a distance from the well within a formation; and   the fluid property analysis system is configured to apply the transform to the velocity model yielding a second predicted fluid property at the fourth location.   
     
     
         20 . The system of  claim 19 , further comprising:
 a well planning system configured to design a borehole drilling plan based on the second predicted fluid property; and   a drilling system configured to drill a borehole based on the borehole drilling plan.