10 Automated Rheology Laboratory Part I V. G. Constien, E. L. Fellin, M . T. King, and G. G. Graves
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Dowell Schlumberger, Tulsa, OK 74101 A computer-controlled rheology laboratory has been constructed to study and optimize f l u i d s used i n hydraulic fracturing applications. Instruments consist of both pressurized c a p i l l a r y viscometers and concentric cylinder rotational viscometers. Computer c o n t r o l , data a c q u i s i t i o n and a n a l y s i s are accomplished by two Hewlett Packard 1000 computers. Custom software provides menu-driven programs for instrument control, data retrieval and data analysis. H y d r a u l i c f r a c t u r i n g i s a method o f s t i m u l a t i n g p r o d u c t i o n o f o i l o r gas from rock f o r m a t i o n s . A f l u i d i s pumped under c o n d i t i o n s o f h i g h p r e s s u r e and h i g h r a t e i n t o t h e f o r m a t i o n t o f r a c t u r e i t . The f l u i d a l s o c a r r i e s sand o r a s i m i l a r proppant m a t e r i a l i n t o t h e fractures. When t h e pumping i s stopped and t h e h y d r a u l i c p r e s s u r e i s r e l e a s e d a t t h e w e l l h e a d , t h e f r a c t u r e p a r t i a l l y c l o s e s on t h e sand l e a v i n g a h i g h l y permeable channel f o r t h e o i l o r gas t o f l o w back t o t h e w e l l . The f l u i d s which a r e used i n t h e h y d r a u l i c f r a c t u r i n g p r o c e s s can be q u i t e complex. L a b o r a t o r y r e s e a r c h and development on t h e s e f l u i d s r e q u i r e many hours o f r h e o l o g y t e s t i n g t o d i s c o v e r s u i t a b l e c o m p o s i t i o n s and systems. To speed t h i s p r o c e s s , an automated s t i m u l a t i o n f l u i d r h e o l o g y l a b o r a t o r y was c o n s t r u c t e d . In t h i s p a p e r , we d e s c r i b e t h e t y p e s o f i n s t r u m e n t s which a r e used i n t h i s l a b o r a t o r y , t h e computer s y s t e m , and how t y n ^ c a l experiments a r e s e t up, r u n , and r e s u l t s s t o r e d and a n a l y z e d . In t h e accompanying paper ( P a r t I I ) , t h e f o c u s i s on t h e automation o f one o f t h e more complex instruments i n t h i s l a b o r a t o r y .
Fluid Compositions T y p i c a l h y d r a u l i c f r a c t u r i n g f l u i d c o m p o s i t i o n s have been d e s c r i b e d by s e v e r a l a u t h o r s Q J . The f l u i d s may be aqueous o r hydrocarbon base and may a l s o c o n t a i n e n e r g i z i n g gases such as n i t r o g e n o r 0097-6156/86/0313-O105S06.00/0 © 1986 American Chemical Society
Provder; Computer Applications in the Polymer Laboratory ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
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COMPUTER APPLICATIONS IN THE POLYMER LABORATORY
carbon d i o x i d e . A t y p i c a l , high-performance, have t h e f o l l o w i n g components.
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aqueous
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Fresh Water Bactericide Antifoam Potassium C h l o r i d e Hydroxypropyl guar Buffer Crosslinker Fluid-Loss Control A d d i t i v e Polymer Degrading A d d i t i v e Surfactant
The purpose o f t h e v a r i o u s i n g r e d i e n t s i s t o p r o v i d e d e s i r a b l e f l u i d p r o p e r t i e s a t d i f f e r e n t t i m e s i n t h e t r e a t m e n t . For example, t h e c r o s s l I n k e r system may be d e s i g n e d t o have a l o w r e a c t i o n r a t e w h i l e t h e f l u i d i s a t l o w t e m p e r a t u r e s ( s u c h as t h o s e found i n t h e m i x i n g t a n k s and b e f o r e t h e f l u i d has t r a v e l e d v e r y f a r i n t o t h e f r a c t u r e ) . Then as t h e f l u i d t e m p e r a t u r e i n c r e a s e s above a t h r e s h o l d v a l u e , t h e c r o s s l i n k i n g r a t e a c c e l e r a t e s and changes t h e r h e o l o g y o f t h e f l u i d t o one more d e s i r a b l e In t h e l o w - s h e a r , but h i g h - t e m p e r a t u r e , environment o f t h e f r a c t u r e . U n f o r t u n a t e l y , from a r e s e a r c h t i m e s t a n d p o i n t , s l i g h t changes i n f l u i d c o m p o s i t i o n o r i n t r e a t m e n t c o n d i t i o n s ( s u c h as pumping r a t e ) can f r e q u e n t l y cause s i g n i f i c a n t changes i n f l u i d r h e o l o g y . To a d e q u a t e l y study and o p t i m i z e f l u i d r h e o l o g y o f t e n r e q u i r e s many hours o f c o m p o s i t i o n vs performance t e s t i n g a t s e v e r a l d i f f e r e n t conditions.
Laboratory Instruments and Computers The c o n f i g u r a t i o n o f t h e l a b o r a t o r y i s shown i n F i g u r e 1. The r h e o l o g y equipment c o n s i s t s o f d i f f e r e n t t y p e s o f v i s c o m e t e r s which a r e used by r e s e a r c h and development personnel t o measure p r o p e r t i e s of hydraulic fracturing f l u i d s . Some o f t h e s e i n s t r u m e n t s a r e n o t commercially a v a i l a b l e and were b u i l t " i n - h o u s e " to simulate s p e c i f i c treatment c o n d i t i o n s . To s u b j e c t t e s t f l u i d s t o t h e f u l l range o f s h e a r , t e m p e r a t u r e and t i m e c o n d i t i o n s which may be encountered i n a t y p i c a l f r a c t u r i n g t r e a t m e n t , d i f f e r e n t i n s t r u m e n t s may be c o u p l e d t o g e t h e r . For example, a c a p i l l a r y v i s c o m e t e r w i t h i n - l i n e a d d i t i v e pumps 1s used t o c o n t i n u o u s l y p r e p a r e f l u i d s and t o s i m u l a t e t h e shear h i s t o r y a f l u i d would e x p e r i e n c e as i t t r a v e l s down t h e t u b u l a r goods on i t s way t o t h e f o r m a t i o n t o be f r a c t u r e d . Once t h e f l u i d e n t e r s t h e f o r m a t i o n , d i f f e r e n t s h e a r , t e m p e r a t u r e and t i m e c o n d i t i o n s a r e encountered. These c o n d i t i o n s a r e s i m u l a t e d i n t h e l a b o r a t o r y by l o a d i n g a p o r t i o n o f t h e f l u i d ( e x i t i n g t h e shear h i s t o r y s i m u l a t o r ) d i r e c t l y i n t o a high-temperature/high-pressure r o t a t i o n a l viscometer or a r e c i p r o c a t i n g c a p i l l a r y viscometer f o r long-term rheology e v a l u a t i o n s ( F i g u r e 2) (2). The computer system f o r t h i s l a b o r a t o r y c o n s i s t s o f a s i n g l e Hewlett Packard 1000 A - S e r i e s minicomputer which i s networked t o an HP 1000 F - S e r i e s host computer. The A - S e r i e s computer was chosen because i t s o p e r a t i n g system (RTE-A) i s r e a l - t i m e , m u l t i u s e r and
Provder; Computer Applications in the Polymer Laboratory ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
Downloaded by EAST CAROLINA UNIV on January 3, 2018 | http://pubs.acs.org Publication Date: June 27, 1986 | doi: 10.1021/bk-1986-0313.ch010
CONSTIEN ET AL.
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Automated Rheology Laboratory: Part I
F i g u r e 1.
Instrument and computer network.
CONCENTRIC CYLINDER VISCOMETER SHEAR HISTORY SIMULATOR
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results.
Literature Cited 1. 2.
3. 4.
M. W. Conway, S. W. Almond, J. E. Briscoe and L. E. Harris: J . Pet. Tech. (Feb. 1983), 315. L. J. Craigie: "A New Method for Determining the Rheology of Crosslinked Fracturing Fluids using Shear History Simulation," SPE/DOE 11635 presented at the 1983 SPE/DOE Symposium on Low Permeability (March 14-16), Denver, Colo. J. G. Savins: "Generalized Newtonian (Pseudoplastic) Flow in Stationary Pipe and Annuli," Pet. Trans., AIME (1958), 213, 325. M. T. King, V. G. Constien and E. L. Fellin: "Automated Rheology Laboratory--Part II: An Automated Instrument for Continuous Rheology Evaluation," submitted to the ACS Symposium, Division of Polymeric Materials: Science and Engineering, Computers in Applied Polymer Science: IV (1985), Miami Beach.
RECEIVED March 4, 1986
Provder; Computer Applications in the Polymer Laboratory ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
