Petroleum Engineering 324 Well Performance Daily Summary Sheet Spring 2009 Blasingame/Ilk. Date: Materials Covered in Class Today: Comment(s):

Transcription

1 Petroleum Engineering 324 Well Performance Daily Summary Sheet Sring 2009 Blasingame/Ilk Date: Materials Covered in Class Today: Comment(s):

2 Petroleum Engineering 324 (2009) Reservoir Performance Material Balance Objective: Derive the material balance relation for a slightly comressible liquid (oil) in the resence of other hases (gas and water), as well as the material balance relation for a dry gas. Deartment of Petroleum Engineering Texas A&M U.

3 Notes: Deartment of Petroleum Engineering Texas A&M U.

4 Material Balance: Historical Persective "It seems no longer fashionable to aly the concet of material balance to oilfields, the belief being that it has now been suerseded by the alication of the more modern technique of numerical simulation modeling. Accetance of this idea has been a TRAGEDY and has robbed engineers of their most owerful tool for investigating reservoirs and understanding their erformance rather than imosing their wills uon them, as is often the case when alying numerical simulation directly in history matching." L.P. Dake The Practice of Reservoir Engineering, Elsevier (2001) Deartment of Petroleum Engineering Texas A&M U.

5 Notes: Deartment of Petroleum Engineering Texas A&M U.

6 Material Balance: Orientation Issues: Oil MBE (must know all data, also c f ()). Gas MBE (abnormal ressure, water drive). Toics: "Accounting" Concet of Material Balance: Require all inflows/outflows/generations. (Average) reservoir ressure rofile is REQUIRED. Require rock, fluid, and rock-fluid roerties (at some scale). Oil Material Balance: Less common than gas material balance (ressure required). Gas Material Balance: Volumetric dry gas reservoir (/z versus G (straight-line)). Abnormally-ressured gas reservoirs (various techniques). Waterdrive/water influx cases (always roblematic). Material Balance yields RESERVOIR VOLUME! Deartment of Petroleum Engineering Texas A&M U.

7 Material Balance: General Concet a. Initial reservoir conditions. b. Conditions after roducing N STB of oil, and G SCF of gas, and W STB of water. From: Petroleum Reservoir Engineering Amyx, Bass, and Whiting (1960). Material Balance: Key Issues Must have accurate roduction measurements (oil, water, gas). Estimates of average reservoir ressure (from ressure tests). Suites of PVT data (oil, gas, water). Reservoir roerties: saturations, formation comressibility, etc. Deartment of Petroleum Engineering Texas A&M U.

8 Material Balance: Average Reservoir Pressure From: Engineering Features of the Schuler Field and Unit Oeration Kaveler (SPE-AIME, 1944). Average Reservoir Pressure: Key Issues Must have "average" ressures over volume or area (aroximation). Pressure tests must be reresentative ( avg extraolation valid). Can average using cumulative roduction (surrogate for volume). Deartment of Petroleum Engineering Texas A&M U.

9 Material Balance: Examle Data Set From: Alication of the Material Balance to a Partial Waterdrive Reservoir van Everdingen (SPE, 1953). Black Oil Material Balance Case: (Examle Data Set) Note that all fluid functions are given: N, W, and GOR (for G ). Average reservoir ressure is resumed correct. Authors cite "artial waterdrive" remains a contentious issue. Deartment of Petroleum Engineering Texas A&M U.

10 Material Balance: Oil Material Balance Relations Oil Material Balance Relations: "Black Oil" Material Balance: (> b ) 1 B = o i N Nc B t oi "Solution Gas Drive" (Oil) Material Balance: (all ) N [ B + ( R R ) B ] o s g + W B w = (Withdrawal (RB)) N [( B B ) + ( R R ) B ] o oi si s g (Oil Exansion (RB)) + mnb + W e B oi + (1 + m) NB w B B g gi oi 1 ( c S w wi (1 S + c wi ) f ) ( i ) (Gas Ca Exansion (RB)) (Water Ex./Pore Vol. Com. (RB)) (Water Influx (RB)) Deartment of Petroleum Engineering Texas A&M U.

11 Material Balance: Recovery Factors (Oil) Examle: Black Oil Recovery (> b ) 1 B N o B = oi i N or = ( Nc B N B oi Black Oil Recovery: t ( 0) B oi /B o =0.95 i =5000 sia c t =10x10-6 si -1 o i ) c t N N N N = = (0.95)((5000 sia) (0 sia))( or 4.75 ercent recovery! x 10 6 si 1 ) Deartment of Petroleum Engineering Texas A&M U.

12 Deartment of Petroleum Engineering Texas A&M U. General Gas Material Balance: "Dry Gas" Material Balance: (no reservoir liquids ) "Abnormal Pressure" Material Balance: (c f =f()) [ ] [ ] + + = e w inj g sw inj i i i i i e W B W W B R W G G G z z c z ) ( ) )( ( 1 = i i G G z z 1 1 [ ] = G G c z z i e i i 1 ) )( ( = ) ( ) (1 1 ) ( f w R AQ R NNP f w wi wi e c c V V V V c c S S c Gas Material Balance Relations: Material Balance: Gas Material Balance Relations

13 Material Balance: Gas Abnormal Pressure Gas Material Balance: Abnormally Pressured Reservoir Schematic Normal ressure roduction sequence (volumetric deletion, G). Abnormal ressure roduction sequence (G a ). Deartment of Petroleum Engineering Texas A&M U.

14 Material Balance: Gas Abn. Pressure (US GOM) Gas Material Balance: Abnormally Pressured Reservoir Schematic Normal ressure roduction sequence (volumetric deletion, G). Abnormal ressure roduction sequence (G a ). Note the osition of the "ivot oint" is at hydrostatic ressure. Deartment of Petroleum Engineering Texas A&M U.

15 Material Balance: Gas Normal Pressure "Dry Gas" Material Balance: Normal Pressured Examle Volumetric reservoir no external energy (gas exansion only). /z versus G yields unique straight-line trend. Linear extraolation yield gas-in-lace (G). Deartment of Petroleum Engineering Texas A&M U.

16 Material Balance: Gas Abnormal Pressure "Dry Gas" Material Balance: Abnormally Pressured Reservoir Volumetric reservoir no water influx or leakage. /z versus G yields unique quadratic trend (aroximate MBE). Quadratic extraolation yield gas-in-lace (G). Deartment of Petroleum Engineering Texas A&M U.

17 Material Balance: Gas Water Influx From: Unsteady-State Performance of Water Drive Gas Reservoirs, Agarwal (Texas A&M Ph.D., 1967). a. Gas Material Balance Plot: /z vs. G simulated erformance. Note effect of aquifer ermeability on field erformance. b. Gas Material Balance Plot: /z vs. G simulated erformance. Note effect of dislacement efficiency (E ). Gas Material Balance: Water Drive Gas Reservoir Pressure (hence /z) is maintained during roduction via water influx. Agarwal used an unsteady-state aquifer for this case. Numerous other aquifer models (analyst must choose). Deartment of Petroleum Engineering Texas A&M U.

18 Material Balance: Questions to Consider Q1. What is the "weakest link" in material balance? A1. Need for very accurate roduction records articularly average reservoir ressure (which is rarely available). Q2. What is the strength of material balance? A2. It is an accounting method, essentially indeendent of the reservoir model. It rovides an estimate of initial reservoir volume being samled by the wells under roduction. Q3. Future of material balance? A3. Difficult to say, essentially being (or has been) relaced by numerical reservoir simulation. Deartment of Petroleum Engineering Texas A&M U.

19 Petroleum Engineering 324 (2009) Reservoir Performance Material Balance Alications in Pressure Transient Testing Deartment of Petroleum Engineering Texas A&M U.

20 Material Balance: Wellbore Storage Equations Deartment of Petroleum Engineering Texas A&M U.

21 Material Balance: Wellbore Storage Behavior i wf (Δt=0) a. Wellbore Storage Plot: Pressure DRAWDOWN case note the early linear ortion of the data. b. Wellbore Storage Plot: Pressure BUILDUP case note the early linear ortion of the data. DRAWDOWN Material Balance Relation: Buildu Material Balance Relation: wf = m t = ( Δt = 0) + m Δt i wbs ws wf wbs Deartment of Petroleum Engineering Texas A&M U.

22 Material Balance: Pseudosteady-State Equations Deartment of Petroleum Engineering Texas A&M U.

23 Material Balance: Pseudosteady-State Flow (Oil) Δ q o = b o,ss + m o,ss N q o Pseudosteady-State Flow: Oil PSS/Boundary-dominated flow is a very strong feature. Simle concet of rate normalization is extremely effective. Difficult to distinguish degradation of roduction. Deartment of Petroleum Engineering Texas A&M U.

24 Material Balance: Pseudosteady-State Flow (Gas) μgi z = i i base d μ z g t a μgicti t qg ( t) = dt q ( t) 0 μ ( ) c ( ) g g t Δ q g = b g, ss + m g, ss t a Pseudosteady-State Flow: Gas Must use "seudo-functions" to account for gas roerties. Note very erratic rate and ressure rofiles (liquid loading). Simle rate normalization also works well for gas case. Deartment of Petroleum Engineering Texas A&M U.

25 One stale here. Name: Section: Date: Petroleum Engineering 324 Well Performance Exercise Problem 05 Well Test "Stri Chart" Summary Plots Assigned: 06 February 2009 Due: 09 February 2009 [to be submitted in class] Assignment Coversheet (This sheet must be included with your work submission) Required Academic Integrity Statement: (Texas A&M University Policy Statement) Academic Integrity Statement All syllabi shall contain a section that states the Aggie Honor Code and refers the student to the Honor Council Rules and Procedures on the web. Aggie Honor Code "An Aggie does not lie, cheat, or steal or tolerate those who do." Uon acceting admission to Texas A&M University, a student immediately assumes a commitment to uhold the Honor Code, to accet resonsibility for learning and to follow the hilosohy and rules of the Honor System. Students will be required to state their commitment on examinations, research aers, and other academic work. Ignorance of the rules does not exclude any member of the Texas A&M University community from the requirements or the rocesses of the Honor System. For additional information lease visit: On all course work, assignments, and examinations at Texas A&M University, the following Honor Pledge shall be rerinted and signed by the student: "On my honor, as an Aggie, I have neither given nor received unauthorized aid on this academic work." (Page 1 of 2) Aggie Code of Honor: An Aggie does not lie, cheat, or steal or tolerate those who do. Required Academic Integrity Statement: "On my honor, as an Aggie, I have neither given nor received unauthorized aid on this academic work." (Print your name) (Your signature) Coursework Coyright Statement: (Texas A&M University Policy Statement) The handouts used in this course are coyrighted. By "handouts," this means all materials generated for this class, which include but are not limited to syllabi, quizzes, exams, lab roblems, in-class materials, review sheets, and additional roblem sets. Because these materials are coyrighted, you do not have the right to coy them, unless you are exressly granted ermission. As commonly defined, lagiarism consists of assing off as one s own the ideas, words, writings, etc., that belong to another. In accordance with this definition, you are committing lagiarism if you coy the work of another erson and turn it in as your own, even if you should have the ermission of that erson. Plagiarism is one of the worst academic sins, for the lagiarist destroys the trust among colleagues without which research cannot be safely communicated. If you have any questions about lagiarism and/or coying, lease consult the latest issue of the Texas A&M University Student Rules, under the section "Scholastic Dishonesty." Zero Tolerance Policy: You MUST submit this assignment in class ONLY.

26 Name: Section: Date: Petroleum Engineering 324 Well Performance Exercise Problem 05 Well Test "Stri Chart" Summary Plots Assigned: 06 February 2009 Due: 09 February 2009 [to be submitted in class] Given: You are given the two Cartesian coordinate lots which are commonly referred to as "Stri Chart" lots for the history of a well test. These lots include only summary data, no analysis is erformed, but you can orient all "events" using such lots. Required: You are to sketch a tyical ressure drawdown/buildu test sequence on the lots given below, and to label all of the ertinent features including trends, secific ressures and/or rates, time scales, etc. as aroriate. You must also sketch in the Δt time scale for the ressure buildu test. (Page 2 of 2) Zero Tolerance Policy: You MUST submit this assignment in class ONLY.

27 One stale here. Name: Section: Date: Petroleum Engineering 324 Well Performance Exercise Problem 05 Well Test "Stri Chart" Summary Plots Assigned: 06 February 2009 Due: 09 February 2009 [to be submitted in class] Assignment Coversheet (This sheet must be included with your work submission) Required Academic Integrity Statement: (Texas A&M University Policy Statement) Academic Integrity Statement All syllabi shall contain a section that states the Aggie Honor Code and refers the student to the Honor Council Rules and Procedures on the web. Aggie Honor Code "An Aggie does not lie, cheat, or steal or tolerate those who do." Uon acceting admission to Texas A&M University, a student immediately assumes a commitment to uhold the Honor Code, to accet resonsibility for learning and to follow the hilosohy and rules of the Honor System. Students will be required to state their commitment on examinations, research aers, and other academic work. Ignorance of the rules does not exclude any member of the Texas A&M University community from the requirements or the rocesses of the Honor System. For additional information lease visit: On all course work, assignments, and examinations at Texas A&M University, the following Honor Pledge shall be rerinted and signed by the student: "On my honor, as an Aggie, I have neither given nor received unauthorized aid on this academic work." (Page 1 of 2) Aggie Code of Honor: An Aggie does not lie, cheat, or steal or tolerate those who do. Required Academic Integrity Statement: "On my honor, as an Aggie, I have neither given nor received unauthorized aid on this academic work." (Print your name) (Your signature) Coursework Coyright Statement: (Texas A&M University Policy Statement) The handouts used in this course are coyrighted. By "handouts," this means all materials generated for this class, which include but are not limited to syllabi, quizzes, exams, lab roblems, in-class materials, review sheets, and additional roblem sets. Because these materials are coyrighted, you do not have the right to coy them, unless you are exressly granted ermission. As commonly defined, lagiarism consists of assing off as one s own the ideas, words, writings, etc., that belong to another. In accordance with this definition, you are committing lagiarism if you coy the work of another erson and turn it in as your own, even if you should have the ermission of that erson. Plagiarism is one of the worst academic sins, for the lagiarist destroys the trust among colleagues without which research cannot be safely communicated. If you have any questions about lagiarism and/or coying, lease consult the latest issue of the Texas A&M University Student Rules, under the section "Scholastic Dishonesty." Zero Tolerance Policy: You MUST submit this assignment in class ONLY.

28 Name: Section: Date: Petroleum Engineering 324 Well Performance Exercise Problem 05 Well Test "Stri Chart" Summary Plots Assigned: 06 February 2009 Due: 09 February 2009 [to be submitted in class] Given: You are given the two Cartesian coordinate lots which are commonly referred to as "Stri Chart" lots for the history of a well test. These lots include only summary data, no analysis is erformed, but you can orient all "events" using such lots. Required: You are to sketch a tyical ressure drawdown/buildu test sequence on the lots given below, and to label all of the ertinent features including trends, secific ressures and/or rates, time scales, etc. as aroriate. You must also sketch in the Δt time scale for the ressure buildu test. (Page 2 of 2) Zero Tolerance Policy: You MUST submit this assignment in class ONLY.

29 Person on my left is: Person on my right is: Name: Petroleum Engineering 324 Well Performance Quiz 06 Wellbore Pressure Profile Pressure Drawdown/Buildu Test Sequence [06 February 2009] 1. You are to sketch a tyical ressure rofile at the wellbore during a ressure drawdown/buildu sequence on the lot given below, and to label all of the ertinent features. You MUST also sketch in the Δt time scale for the ressure buildu test. Aggie Code of Honor: An Aggie does not lie, cheat, or steal or tolerate those who do. Required Academic Integrity Statement: (Texas A&M University Policy on Academic Integrity) "On my honor, as an Aggie, I have neither given nor received unauthorized aid on this academic work." (your signature)

30 Person on my left is: Person on my right is: Name: Petroleum Engineering 324 Well Performance Quiz 06 Wellbore Pressure Profile Pressure Drawdown/Buildu Test Sequence [06 February 2009] 1. You are to sketch a tyical ressure rofile at the wellbore during a ressure drawdown/buildu sequence on the lot given below, and to label all of the ertinent features. You MUST also sketch in the Δt time scale for the ressure buildu test. Aggie Code of Honor: An Aggie does not lie, cheat, or steal or tolerate those who do. Required Academic Integrity Statement: (Texas A&M University Policy on Academic Integrity) "On my honor, as an Aggie, I have neither given nor received unauthorized aid on this academic work." (your signature)