Title of Invention

"A METHOD OF TREATING SUBTERRANEAN FORMATION OF AN OIL RESERVOIR TO CONTROL UNWANTED WATER PRODUCTION AND ENHANCE OIL PRODUCTION, THROUGH A SEQUENCE OF CHEMICAL TREATMENT"

Abstract

A self selective bio-polymer gel composition, and method of treating subterranean formations in an oil well to reduce water production and enhance oil production, comprising water in the range of 70% to 85% of the weight of the composition, a xanthan co-polymer of biological origin taken in the range of 0.2 to 0.6% of the composition, a water soluble crosslinking agent and a water soluble bactericide, is selected from the group consisting of chromium chloride or chromium acetate or chromium propionate and the weight of the crosslinking agent is taken in the range of 0.03 to 0.1 percent of total weight of the composition, a bactericide used is selected from the formaldehyde or glutaraldehyde in the range of 0.5% to 2% of the weight of the composition, a water suspendable polymer is starch powder is taken in the range of 0.2 to about 0,8 percent of the weight of the composition a cellulose based fibrous polymer which may be poly anionic cellulose or cellulose ether from about 1 to about 3 percent of the weight of the composition and a suspendable particulate matter is taken from calcium carbonate powder or silica flour of grain size from 25 –100 micron and the weight of which is from about 10 to about 20 percent of the weight of the composition.

Full Text

FORM-2 THE PATENTS ACT, 1970 (39 of 1970) COMPELETE SPECIFICATION [Section 10; rule 13] A SELF SELECTIVE BIO-POLYMER GEL COMPOSITION, FOR PERMEABILITY MODIFICATION AND METHOD OF TREATING AN OIL WELL FOR LIMITING WATER PRODUCTION Dr. BISWESWAR GHOSH C/O SAURAVSAH 204^ WING, SHRADHHA MAHAL CHINCHPARA ROAD, (NEAR SAKET COLLEGE TURNING) KALVAN(EAST), DIST-THANE,PIN-42I306 INDIAN The following specification particularly describes the nature of the invention and the manner in which it is to, be performed. Field of the invention:- The present invention relates to a self selective bio-polymer gel composition. The invention further relates to methods of using self selective bio-polymer gel compositions in subterranean formations to arrest unwanted water production from an oil well. Back Ground and prior art:- The following patents are known, related to the application based on the methods of utilization of natural/synthetic gelling polymers for water control in oil wells. US patent No. 4524829 disclosing a method of altering the permeability of a subterranean formation by contacting the formation with a water dispersible hydrophilic organic polymer and a crosslinking zirconium compound, US Patent 4809789 which discloses method for selectively plugging highly permeable zones in a subterranean formation with xanthan/chromium gel solution US patent No. 4856586 discloses method for selectively closing pores in a zone of greater permeability in a formation with xanthan biopolymer combined with a crosslinked non-selective polyacrylamide polymer gel. US patent No. 4917186 which discloses a method for altering subterranean formation permeability with polymer capable of being gelled when contacted with a crosslinking agent. US patent No. 4994194 disclosing a method and composition for altering the permeability of a high temperature subterranean formation comprising acrylamide polymer and a delayed crosslinking combination of an aldehyde and salicylic acid derivative. US patent No. 5067564 disclosing a process of selectively placing a permeability-reducing material to inhibit fluid communication between a near well bore interval and an underlying water source. US Patent No. 5071890 discloses composition for selective placement of polymer gels for profile control in thermal oil recovery comprising water dispersible polymers, phenolic compounds, and aldehyde producing compounds US Patent No. 5145012 disclosing method for selectively reducing subterranean water permeability by gels containing gas precursors and gel degrading agent such as acids. US Patent 5322123 discloses process of using zirconium lactate crosslinked scleroglucan gel compositions for reducing the production of water in oil- or gas-producing wells. US Patent 5377760 which discloses method of preparation of fiber reinforced gel for use in subterranean treatment in which glass fibers and cellulosic fibers were used US Patent 5415229 which discloses oil recovery process utilizing a gel containing a crosslinkable polymer and chromium(III)/earboxylate complex as crosslinking agent. US Patent 6156819 which discloses use of low- and high-molecular-weight polymers and a method for treating subterranean formations US patent No. 6176315 disclosing a method of preventing flow through subterranean zones by polymeric sealing composition US Patent No. 6192986 describes a blocking composition for use in subterranean formation comprising one non-acidic unsaturated polar monomer, one copolymerisable ethylenically unsaturated ester; and an organic gelling agent. Summery of the invention :- This article describes invention and method of application of a bio-polymer based gel product through which the relatively high permeable zones in a subterranean sandstone formation called a thief zone which produces mainly water and little or no oil, in a petroleum well, can be selectively plugged off to produce more oil from the oil rich, relatively low permeability sandstone formation. Due to novelty of the invention the gel placement can be performed without use of zone isolation tool thereby reduce cost of operation. The base fluid is a gellable xanthan polymer solution of suitable viscosity with or without a crosslinking compound of chromium (sup +3) ion. This solution will enter both into low and high permeable zone and block both oil and water flow. The novelty of the present invention is introduction of a suspendable fibrous polymer of suitable molecular size and inert suspendable particulate material. When the combined mixture is injected into the wellbore formation with sufficient pressure, the suspended polymer and the particulates form an impermeable layer on the low permeable zone because of the smaller pore size and thereby protecting this oil bearing zone from invasion of solidifiable plugging materials whereas because of higher pore size the whole solution will penetrate into the high permeable water bearing formation and plug this area selectively thereby when the well is open for production more oil and less water will be produced. Description of the Invention:- The present invention is described in the context of specific terms which are defined as follows. An oil well is drilled through subterranean formation consists of two general regions, the "matrix" and "anomalies." An "anomaly" is a volume in the formation having very high permeability relative to the matrix. The "matrix" is characterized as essentially homogeneous, continuous, sedimentary reservoir material free of anomalies. The term "gel" as used here is directed to a continuous non-flowing three-dimensional crosslinked polymeric network having an ultra high molecular weight so as not to propagate from the confines of the desired treatment region. During the life of oil production it is often necessary to inject water or watery fluid from injection wells into the oil reservoir to maintain pressure and to sweep the oil. However due to high permeability and consequently higher flow rate oil is swept mainly from the anomalies and finally only water is produced bypassing remaining oil in the low permeable matrix region. The present invention relates to a self selective bio-polymer gel composition and process of making the same. The invention further relates to methods of using self selective bio-polymer gel compositions in subterranean formations to limit unwanted water production from anomalies primarily due to preferential penetration into high permeable zones and also due to its intrinsic relative permeability modification properties. The said composition comprises water from about 70 percent to about 85 percent of the weight of the composition. The water soluble bio-polymer comprises a xanthan co-polymer of biological origin. The weight of polymer is from 0.2 to about 0.8 percent of the weight of the composition. V A water soluble crosslinking agent selected from the group consisting of chromium chloride or chromium acetate or chromium propionate and the weight of the crosslinking agent is taken in the range of 0.03 to 0.1 percent of total weight of the composition. An aldehyde as bactericide, either formaldehyde or glutaraldehyde depending on microorganism present in the subterranean formation and the weight of the bactericide is from about 0.5 to about 2 percent of the weight of the composition A water suspendable polymer is starch powder derived from potato or maize and the weight of starch in the composition is in the range of 0.2 to about 0.8 percent of the weight of the composition. Another commercially available cellulose based fibrous polymer which may be poly anionic cellulose or cellulose ether from about 1 to about 3 percent of the weight of the composition. The suspendable particulate matter is calcium carbonate powder or silica flour of grain size from 25 - 100 micron, and the weight of calcium carbonate composition is from about 10 to about 20 percent of the weight of the composition. Still further, the present invention is directed to a method for treating a subterranean formation of an oil producing well. The method comprises squeezing the gel composition at sufficient pressure and creating an impermeable filter cake by suspendable calcium carbonate particle which act as bridging agent and water suspendable starch polymer and cellulose fibre which covers the remaining pore spaces of the filter cake. This filter cake is formed only on the relatively low permeable matrix and not on the water bearing high permeability anmalis due to careful selection of particle size of the suspendable materials. Thereby the water soluble bio-polymer and crosslinking agent is unable to penetrate and plug the low permeable formation but the whole composition will invade the high permeable water bearing formation. The water soluble bio-polymer and the crosslinking agent will react in the formation temperature from 50 to 90 oC to form a semisolid gel. The present invention is further directed to the method of arresting unwanted water production from an oil well by selectively treating only the water producing formation and protecting the oil producing formation from getting plugged without using any oil rig and zone isolation mechanical device, thereby reducing cost of the well treatment significantly Finally, the present invention is directed to a method for treating a subterranean formation with a relative permeability modifier gel system which, if by any chance invades a relatively higher oil bearing formation, due to its very nature of preferential plugging of water bearing zones will not create much damage to the permeability of oil and thereby oil production rate. We Claim 1. A self selective bio-polymer gel composition, and method of treating subterranean formations in an oil well to reduce water production and enhance oil production, comprising water in the range of 70% to 85% of the weight of the composition, a xanthan co-polymer of biological origin taken in the range of 0.2% to 0.6% of the weight of the composition, a water soluble soluble crosslinking agent and a water soluble bactericide, is selected from the group consisting of chromium chloride or chromium acetate or chromium propionate and the weight of the crosslinking agent is taken in the range of 0.03 to 0.1 percent of total weight of the composition, a bactericide used is selected from the formaldehyde or glutaraldehyde in the range of 0.5% to 2% of the weight of the composition, a water suspendable polymer is starch powder is taken in the range of 0.2 to about 0,8 percent of the weight of the composition a cellulose based fibrous polymer which may be poly anionic cellulose or cellulose ether from about 1 to about .3 percent of the weight of the composition and a suspendable particulate matter is taken from calcium carbonate powder or silica flour of grain size from 25 - 100 micron, and the weight of which is from about 10 to about 20 percent of the weight of the composition. 2. A composition as claimed in claim 1, where in treating a subterranean formation of an oil producing well comprising the following steps comprising squeezing the composition at sufficient pressure and creating an impermeable filter cake by suspendable calcium carbonate particle which act as bridging agent and water suspendable starch polymer and cellulose material which covers the remaining pore spaces of the filter cake, the water soluble bio-polymer and the crosslinking agent will react in the formation temperature from 50 to 90 oC to form a semisolid gel. 3. A self selective bio-polymer gel composition, for ' permeability modification and method of limiting unwanted water production from an oil well such as here in described with reference to the description.

Documents:

128-MUM-2008-ABSTRACT(16-11-2009).pdf

128-MUM-2008-ABSTRACT(18-1-2008).pdf

128-MUM-2008-ABSTRACT(GRANTED)-(7-5-2010).pdf

128-MUM-2008-CANCELLED PAGES(1-4-2010).pdf

128-MUM-2008-CLAIMS(18-1-2008).pdf

128-MUM-2008-CLAIMS(AMENDED)-(16-11-2009).pdf

128-mum-2008-claims(complete)-(16-11-2009).pdf

128-MUM-2008-CLAIMS(GRANTED)-(7-5-2010).pdf

128-mum-2008-claims.doc

128-mum-2008-claims.pdf

128-MUM-2008-CORRESPONDENCE 1(1-4-2010).pdf

128-MUM-2008-CORRESPONDENCE(21-1-2008).pdf

128-MUM-2008-CORRESPONDENCE(24-4-2009).pdf

128-MUM-2008-CORRESPONDENCE(IPO)-(1-7-2010).pdf

128-MUM-2008-CORRESPONDENCE(IPO)-(27-5-2009).pdf

128-MUM-2008-CORRESPONDENCE(IPO)-(31-12-2008).pdf

128-mum-2008-description (complete).pdf

128-mum-2008-description(complete)-(16-11-2009).pdf

128-MUM-2008-DESCRIPTION(COMPLETE)-(18-1-2008).pdf

128-MUM-2008-DESCRIPTION(GRANTED)-(7-5-2010).pdf

128-MUM-2008-FORM 1(16-11-2009).pdf

128-MUM-2008-FORM 1(18-1-2008).pdf

128-mum-2008-form 13(24-4-2009).pdf

128-mum-2008-form 2(16-11-2009).pdf

128-mum-2008-form 2(complete)-(16-11-2009).pdf

128-MUM-2008-FORM 2(COMPLETE)-(18-1-2008).pdf

128-MUM-2008-FORM 2(GRANTED)-(7-5-2010).pdf

128-MUM-2008-FORM 2(TITLE PAGE)-(1-4-2010).pdf

128-MUM-2008-FORM 2(TITLE PAGE)-(16-11-2009).pdf

128-MUM-2008-FORM 2(TITLE PAGE)-(18-1-2008).pdf

128-mum-2008-form 2(title page)-(complete)-(16-11-2009).pdf

128-MUM-2008-FORM 2(TITLE PAGE)-(GRANTED)-(7-5-2010).pdf

128-MUM-2008-FORM 26(12-11-2009).pdf

128-MUM-2008-FORM 3(16-11-2009).pdf

128-MUM-2008-FORM 3(18-1-2008).pdf

128-mum-2008-form 3(8-1-2008).pdf

128-MUM-2008-FORM 9(18-1-2008).pdf

128-mum-2008-form-1.pdf

128-mum-2008-form-18.pdf

128-mum-2008-form-2.doc

128-mum-2008-form-2.pdf

128-mum-2008-form-9.pdf

128-MUM-2008-REPLY TO EXAMINATION REPORT(16-11-2009).pdf

128-MUM-2008-SPECIFICATION(AMENDED)-(1-4-2010).pdf

128-MUM-2008-SPECIFICATION(AMENDED)-(16-11-2009).pdf