Apparatus and methods for wellbore completion

Abstract

A bottomhole assembly deployable into a wellbore on coiled tubing and which has at least a casing collar locator, a fluid-delivery apparatus for delivery treatment fluid and a sealing element, typically a packer positioned therebetween, permits delivery of treatment fluid to a plurality of ports formed in casing through either the annulus between the BHA and the casing, through the coiled tubing or through both. Variable volumes of treatment fluid can be delivered as a result of the different volumes of the coiled tubing and the annulus or the combined volume of both. Sleeves used to cover the fracturing ports in the casing to permit selective opening and fracturing therethrough are made shorter than prior art sleeves as a result of the particular arrangement of the BHA and engagement of collars in the casing with the casing collar locator.

The embodiments in which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . A system for treatment of a formation from a wellbore cased with casing, the cased wellbore penetrating the formation, the system comprising:
 a plurality of ported subs incorporated in the casing and forming a contiguous casing bore, each ported sub having
 a plurality of treatment ports formed therethrough between the casing bore and the formation, and 
 at least a sleeve for selectively opening and closing the plurality of treatment ports; and 
   a bottom hole assembly (BHA) deployable on coiled tubing through the casing bore and forming a treatment annulus therebetween, treatment fluid being deliverable to the BHA through the coiled tubing, the BHA having at least:
 a BHA bore contiguous with the coiled tubing; 
 a treatment sub having fluid ports therein for fluid communication between the BHA bore and the treatment annulus; 
 a resettable sealing element spaced downhole the treatment sub for releasably sealing the treatment annulus therebelow; and 
 a fluid block in the BHA bore downhole the treatment sub for blocking treatment fluid therebelow, 
   wherein when the sealing element seals the treatment annulus, treatment fluid is deliverable through the treatment ports either
 through the coiled tubing and fluid ports, 
 through the treatment annulus, or 
 through both the coiled tubing and fluid ports, and the treatment annulus. 
   
     
     
         2 . The system of  claim 1  wherein the plurality of ported subs are spaced along the cased wellbore, each ported sub incorporated therein by a casing collar at, at least, a downhole end thereof, the BHA further comprising:
 a casing collar locator spaced downhole of the sealing element for detecting the casing collar of the ported sub for positioning the BHA relative to the treatment ports. 
 
     
     
         3 . The system of  claim 1  wherein the BHA further comprises:
 a fluid jet assembly positioned uphole from the treatment sub and having a jet bore contiguous with the BHA bore and a plurality of jet ports therein for fluid communication between the BHA bore and the treatment annulus, 
 the fluid jet assembly comprising a jet valve which
 when open, permits treatment fluid to be delivered through the coiled tubing, through the fluid jet assembly and to the fluid ports in the treatment sub below; and 
 when closed, blocks the jet bore to deliver fluid from the coiled tubing and through the plurality of jet ports for cutting jetted openings through the cased wellbore to access the formation. 
 
 
     
     
         4 . The system of  claim 3  wherein a major volume of the treatment fluid is delivered to the fluid ports and a minor volume of the treatment fluid leaks through the plurality of jet ports. 
     
     
         5 . The system of  claim 4  wherein the minor volume of the treatment fluid clears debris from the treatment annulus. 
     
     
         6 . The system of  claim 1  further comprising a pressure equalization valve for equalizing pressure above and below the sealing element so as to permit downhole movement of the BHA within the cased wellbore. 
     
     
         7 . The system of  claim 6  wherein the fluid block comprises the pressure equalization valve. 
     
     
         8 . The system of  claim 1  wherein the fluid block comprises a one-way valve positioned in the BHA bore below the treatment sub for blocking fluid delivery downhole and permitting fluid flow uphole therethrough. 
     
     
         9 . The system of  claim 8  wherein the one-way valve is within the BHA bore at about the resettable sealing element. 
     
     
         10 . The system of  claim 1  wherein the resettable sealing element is a resettable packer. 
     
     
         11 . The system of  claim 1  wherein the casing is cemented into the wellbore, the system further comprising a chemical or fluid retarder positioned in the treatment ports to weaken cement thereabout. 
     
     
         12 . The system of  claim 3  wherein the jet valve comprises:
 a ball seat in the BHA bore downhole of the plurality of jet ports and closable using a ball, deployable through the coiled tubing, to seat in the ball seat. 
 
     
     
         13 . The system of  claim 12  wherein the jet valve is openable by circulating fluid down the treatment annulus, through the fluid ports and into the treatment sub for unseating the ball from the ball seat and circulating the ball therein up the coiled tubing. 
     
     
         14 . The system of  claim 1  wherein the jet valve is openable by applying fluid pressure to the ball above a threshold pressure to open the ball seat and pass the ball therethrough. 
     
     
         15 . The system of  claim 1  wherein each of the plurality of sliding sleeves is about 3 feet in length. 
     
     
         16 . A method of treating a formation comprising:
 deploying a bottom hole assembly (BHA) on coiled tubing into a cased wellbore penetrating the formation and forming a treatment annulus therebetween   locating a ported sub in the cased wellbore, using the BHA for positioning fluid ports of a treatment sub adjacent treatment ports of the ported sub;   sealing the treatment annulus below the treatment sub;   actuating the ported sub to open the treatment ports; and   delivering treatment fluid to the opened treatment ports through either the coiled tubing to the fluid ports, through the treatment annulus or both.   
     
     
         17 . The method of  claim 16 , before delivering the treatment fluid to the opened treatment ports wherein the BHA has a bore formed therethrough and a pressure equalization valve located therein, further comprising:
 blocking the flow of treatment fluid through the BHA's bore below the treatment sub using the pressure equalization valve; and   following delivery of treatment fluid therethrough, opening the pressure equalization valve for moving the BHA in the cased wellbore.   
     
     
         18 . The method of  claim 16  wherein the locating of the ported sub comprises engaging a locating collar at a downhole end of the ported sub with a casing collar locator at downhole end of the BHA. 
     
     
         19 . The method of  claim 16 , wherein delivering treatment fluid through the coiled tubing and fluid ports to the opened treatment ports further comprises delivering deadhead fluid through the treatment annulus. 
     
     
         20 . The method of  claim 16 , wherein delivering treatment fluid to the plurality of treatment ports through the treatment annulus further comprises delivering a deadhead fluid through the coiled tubing. 
     
     
         21 . The method of  claim 16 , wherein when the treatment ports fail to open, jetted openings are formed in the cased wellbore to access the formation using a fluid jet assembly comprising:
 temporarily blocking fluid flow to the treatment sub;   delivering an abrasive fluid through a fluid jet assembly above the treatment sub for cutting one or more jetted openings therein; and   unblocking the fluid flow to the treatment sub to permit fluid flow to the fluid ports.   
     
     
         22 . The method of  claim 21  wherein
 the temporary blocking of the fluid flow comprises deploying a ball down the coiled tubing to seal at a ball seat in a jet valve uphole of the treatment sub; and 
 the unblocking of the fluid flow comprises circulating the ball off of the ball seat. 
 
     
     
         23 . The method of  claim 22  wherein the circulating the ball off of the ball seat further comprises delivering fluid through the treatment annulus and through the delivery fluid for lifting and recirculating the ball up the coiled tubing. 
     
     
         24 . The method of  claim 21  wherein the method of unblocking the fluid flow comprises applying pressure at a threshold for passing the ball through the ball seat.