Analysis of drilling cuttings

Abstract

The invention relates to the analysis of fluid flow paths in a subterranean hydrocarbon reservoir by analyzing rock cuttings from drilling new wells. Previously injected tracers may be isolated from the rock cuttings and analyzed with reference to the history of when and where they were injected. In this way, further information about fluid flow paths in the reservoir may be obtained from different locations in the reservoir without injecting fresh tracers. Cuttings may be analyzed from either production or injection wells.

1 . A method of analyzing fluid flow paths in a hydrocarbon reservoir, the method comprising:
 a) drilling a production well into the reservoir;   b) whilst drilling, circulating drilling fluid into the well and retrieving returned drilling fluid together with rock cuttings;   c) analyzing the rock cuttings for the presence of tracers.   
     
     
         2 . The method according to  claim 1 , wherein the rock cuttings contain tracers previously injected into the reservoir through a different well. 
     
     
         3 . The method according to  claim 1 , wherein the step of analyzing rock cuttings includes identifying a well or wells from which tracers originate. 
     
     
         4 . The method according to  claim 3 , wherein differentiable tracers have previously been injected into respective wells. 
     
     
         5 . The method according to  claim 1 , wherein fluid flow paths within the reservoir are deduced based on the receipt and analysis of tracers in rock cuttings. 
     
     
         6 . The method according to  claim 1 , wherein a substantial time has elapsed between injection of tracers into the reservoir and drilling the production well. 
     
     
         7 . The method according to  claim 6 , wherein the said substantial time is between 5 and 50 years, including a period selected from at least 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 years. 
     
     
         8 . The method according to  claim 1 , including making a decision about where to drill a further production well or injection well, based on the presence and variety of tracers in cuttings from the original production well.